Virology
John J. Kopchick, Ph.D.
What happens after a virus infects the body?Colored slide: H-2
Major Families of Major Families of Animal VirusesAnimal Viruses
DNA Containing Viruses
RNA containing Viruses
Major Families of Animal Major Families of Animal
VirusesViruses DNA Containing Viruses
PoxviridaeChorodopoxvirin
aeGenus
Orthopoxvirus
Subfamily Host Symptoms in Humans
Variola major Humans Smallpox
Monkeypox Monkey, humans
Smallpox-like disease
Cowpox Cattle, humans Vesicular eruption of the skin
Major Families of Animal VirusesMajor Families of Animal Viruses DNA Containing Viruses
HerpesviridaeAlphaherpesvirinaeGenus Simplexvirus
Subfamily Host Symptoms in Humans
Human herpesvirus 1 (herpes simplex virus
type 1 (HSV 1))
Humans Infections of the oropharynx, eye, skin, and genitalia; generalized systemic disease; severe and generally fatal encephalitis
Human herpesvirus 2(herpes simplex virus
type 2 (HSV 2))
Humans Primary genital infections
Cercopithecine herpesvirus 1 (B virus)
Humans, monkeys Fatal encephalitis
Members of the family herpesviridae are found in a wide range of host systems. To date, at least seven different species are known to infect man, including herpes simplex virus (HSV); cytomegalovirus
(CMV), varicella zoster (VZV); and Epstein Barr virus (EBV).
Herpesviruses have an envelope surrounding an icosahedral capsid, approximately 100nm in diameter, which contains the dsDNA genome. When the envelope breaks and collapses away from the capsid, negatively stained virions have a typical "fried-egg" appearance.
Herpesvirus
Major Families of Animal Major Families of Animal
VirusesViruses DNA Containing Viruses
AdenoviridaeGenus Mastadenovirus
Human adenoviruses41 serotypes
Subfamily Host Symptoms in Humans
Subgroup ASerotypes:12, 18
& 31
Humans Regularly isolated from feces of apparently healthy individuals; high incidence of antibodies
Subgroup BSerotypes:
3,7,11,14,16,21,34,35
Humans Acute respiratory disease (also 4); pharyngitis (3,7); acute hemorrhagic cystitis in children (11, 12); low incidence of antibodies
Adenovirus
Adenoviruses are non-enveloped icosahedral particles.The capsid is built up from 252 capsomers (T=25), of which 240 are
hexavalent and 12 (situated at the apices) are pentavalent.A "penton fibre"projects from each apex.
Adenoviruses that infect humans are usually mild pathogens, and can cause respiratory illness or conjunctivitis (so-called "pink eye"), but under laboratory conditions some human strains can transform cells
in culture.
Major Families of Animal Major Families of Animal
VirusesViruses DNA Containing Viruses
PapovaviridaeHuman Papilloma
Viruses (HPV) 1-34Genus Papillomavirus
Subfamily Host Symptoms in Humans
HPV 1&4 Humans Planter warts
HPV 2&4 Humans Common warts (verruca vulgaris)
HPV 3&10 Humans Flat warts (verruca plana) and/or epidermodysplasia verruciformis (EV)
HPV 5,8,9,12,14,15,17,19-25
Humans Red-brown 9macular) plaques of EV (potential for malignancy in light exposed areas)
Papillomavirus
Many types of papillomavirus cause benign skin tumours (warts) in their
natural hosts. These warts often regress spontaneously, but human genital warts (tumours caused by specific types of papillomavirus,
particularly types 16 and 18) regularly become malignant if they persist for a sufficiently long time.
Papillomavirus particles are approximately 55nm in diameter.
The capsid is composed of 72 morphological units, or capsomers, arranged on the surface of a T=7 icosahedron. The capsomers located at each of the 12 vertices, are pentavalent (i.e. each is surrounded by five adjacent capsomers), and the other 60 capsomers are hexavalent (each adjacent to six capsomers).
Major Families of Animal Major Families of Animal
VirusesViruses DNA Containing Viruses
HepadnaviridaeHepatitis B virus
(HBV)
Subfamily Host Symptoms in Humans
Hepatitis B Virus
Humans Acute and chronic hepatitis; cirrhosis; hepatocellular carcinoma; immune complex disease; polyarteritis; glomerulonephritis; infantile papular acrodermatitis; aplastic anemia
Hepatitis B Virus
Hepatitis B virus causes both acute and chronic liver infections in man. An unusual feature is the prolonged viraemia, lasting for up to several months in
acute infections and for many years (even for life) in chronic infections.
A diagrammatic representation of the hepatitis B virion and the surface antigen components
.
Virions are 42nm in diameter and possess an isometric nucleocapsid or "core" of 27nm in diameter, surrounded by an outer coat
approximately 4nm thick. The protein of the virion coat is termed "surface antigen" or HBsAg. It is sometimes extended as a tubular tail on one side of the virus particle. The surface antigen is generally
produced in vast excess, and is found in the blood of infected individuals in the form of filamentous and spherical particles.
Filamentous particles are identical to the virion "tails" - they vary in length and have a mean diameter of about 22nm. They sometimes
display regular, non-helical transverse striations.
Hepatitis B virus
RNA Containing Viruses
Major Families of Animal Major Families of Animal
VirusesViruses RNA Containing Viruses
PicornaviridaeGenus
EnterovirusHuman
enteroviruses
Subfamily Host Symptoms in Humans
Poliovirus3 serotypes
Humans, monkey
Poliomyelitis
Coxsackle virus A
23 serotype (1-24; A23 is ECHO
virus 9)
Humans, mouse Primarily general striated muscle damage; herpangina, aseptic meningitis; paralysis; the common cold syndrome
Enteroviruses(Picornaviruses)
The family Picornaviridae is one of the largest of the viral families, and contains some of the smallest (pico) RNA viruses known to infect man.
The family is divided into five genera: enteroviruses, rhinoviruses (cause of the common cold), cardioviruses, apthoviruses and hepatoviruses (cause of
hepatitis A). The enterovirus genus is so-called because these viruses generally
replicate in the intestine. The most important enterovirus pathogens include poliovirus and Coxsackie A and B viruses.
Virions are icosahedral and about 30nm in diameter. Each capsid is composed of 60 copies of 4 structuralproteins - VP1, VP2, and VP3 are exposed on the virion surface, while VP4 lies buried in close association with the RNA core. Immunogenic sites are located on the exposed external parts of the capsid. The electron micrograph illustrates an immune complex of enterovirus particles linked by antibody molecules.
Major Families of Animal Major Families of Animal
VirusesViruses RNA Containing Viruses
ReoviridaeGenus
Orthoreovirus
Subfamily Host Symptoms in Humans
Mammalian reoviruses3 serotypes
Humans, other mammals
Pathogenicity not established
Colorado tick fever virus
Ticks, Mammals Encephalitis
Genus Rotavirus
Human rotavirus Humans Acute infantile gastroenteritis
Rotavirus
Rotaviruses infect the lining of the intestine and cause diarrhoea, especially in children.Rotavirus particles are approximately 75nm in diameter. They have icosahedral symmetry and particles possess two concentric protein shells, or capsids. The term "rota", meaning wheel, is derived from the appearance of the complete double-capsid particle when viewed by negative
staining in a position where the 5-fold axis of symmetry is acentric. Apparent spoke-like components are then visible on one side of the virus particle.
A double-capsid particle is shown on the left, and the single (inner) capsid on its right.
The arrangement of capsomers on the inner capsid gives the appearance of a lattice - 5 capsomers surround a space at each apex
(5-fold axis)
Major Families of Animal Major Families of Animal
VirusesViruses RNA Containing Viruses
OrthomyxoviridaeGenus Influenzavirus
Subfamily Host Symptoms in Humans
Influenza virus type AHuman subtypes
A0 (H1N1) 1933-1947 & 1977-present
A1 (H1N1) 1947-1957A2 (H2N2) 1957-1968
(Asian)A3 (H3N2) 1968-present
(Hong Kong)
Humans
Acute respiratory disease
Acute respiratory diseaseAcute respiratory disease
Acute respiratory disease
Swine influenze virus Swine Acute respiratory disease
Influenza virusInfluenza virus (an Orthomyxovirus) is responsible for acute upper respiratory disease, usually accompanied by fever and myalgia.
Virions are usually roughly spherical and about 200nm in
diameter. The envelope contains rigid
"spikes" of haemagglutinin and neuraminidase which form a characteristic halo of
projections around negatively stained virus particles.
The viral genome is composed of eight segments of ssRNA.
The helical ribonucleo-protein is not often seen,but occasional particles show evidence of internal helical
components
Major Families of Animal Major Families of Animal
VirusesViruses RNA Containing Viruses
RetroviridaeGenus
Oncornavirus CHuman T-cell
leukemia/lymphoma virus
Subfamily Host Symptoms in Humans
HTLV-IHumans Isolated from
patients with cutaneou T-cell lymphomas and adult T-cell leukemia
HTLV-II Humans Isolated from a T-cell line established from a patient with a variant of hairy cell leukemia
Major Families of Animal Major Families of Animal
VirusesViruses RNA Containing VirusesRetroviridae, continued
Lentivirinae
Subfamily Host Symptoms in Humans
Human immunodeficiency
virus (HIV) also known as human T-
cell leukemia virus III (HTLV-III) or
lymphadenopathy associated virus
(LAV)
Humans Acquired immune deficiency syndrome (AIDS)
Major Families of Animal VirusesMajor Families of Animal Viruses DNA Containing Viruses
Poxviridae, ContinuedChorodopoxvirin
aeGenus
Parapoxvirus
Subfamily Host Symptoms in Humans
Orf (contagious pustular
dermatitis CPD)
Sheep, goats, humans
Nodules on hands
Pseudocowpos (milkers nodule
virus)
Cattle,humans Nodules on hands
Ungrouped
Subfamily Host Symptoms in Humans
Molluscum contagiosum
Humans Benign epidermal tumors
Tanapoxvirus Humans Short febrile illness, pocklike skin lesions
Yaba monkey tumor virus
Monkeys, humans
Benign epidermal tumors that soon regress
Major Families of Animal Major Families of Animal
VirusesViruses DNA Containing Viruses
Poxviridae, Continued
Major Families of Animal VirusesMajor Families of Animal Viruses DNA Containing Viruses
Herpesviridae, continuedAlphaherpesvirinaeGenus Simplexvirus
Subfamily Host Symptoms in Humans
Human herpesvirus 3
(varicella-zoster virus (VZV))
Humans Chickenpox, herpes zoster
BetaherpesvirinaeGenus
Cytomegalovirus
Human herpesvirus 5
(human cytomegaloviruses
(HCMV))
Humans Jaundice, hepatosplenomegaly, brain damage, death
Major Families of Animal Major Families of Animal
VirusesViruses DNA Containing Viruses
Herpesviridae, continuedGammaherpesvi
rinaeGenus
Lymphocryptovirus
Subfamily Host Symptoms in Humans
Human herpesvirus 4(Epstein-Barr virus (EBV))
Humans Infectious mononucleosis, Burkitt’s lymphoma, nasopharyngeal carcinoma
Major Families of Animal Major Families of Animal
VirusesViruses DNA Containing VirusesAdenoviridae, continuedSubfamily Host Symptoms in Humans
Subgroup CSerotypes:1,2,5,6
Humans Mild infections of the respiratory tract, especially in infants and children; pneumonia in infants and young children (1,2,3,& 7); pertussislike syndrome in infants and young children (5)
Subgroup DSerotypes:
8,9,10,13,15,17,19,20,22-30, 32,33,36-39
Humans Epidemic keratoconjunctivitis (8,11,19,37); low incidence of antibodies
Subgroup ESerotypes: 4
Humans Acute respiratory disease
Major Families of Animal Major Families of Animal
VirusesViruses DNA Containing VirusesAdenoviridae, continued
Subfamily Host Symptoms in Humans
Subgroup FSerotypes: 40
Humans Acute gastrointestinal disease in children
Subgroup GSerotypes: 41
Humans Acute gastrointestinal disease in children
Major Families of Animal Major Families of Animal
VirusesViruses DNA Containing Viruses
Papovaviridae, continuedSubfamily Host Symptoms in
Humans
HPV 6 & 11 Humans Anogential warts (condylomata acminata), otolaryngeal warts
HPV 7 Humans Meat handler’s warts
HPV 2&4 Humans Common warts (verruca vulgaris)
HPV 13 Humans Oral focal hyperplasia
HPV 16,18,31,33 and 34
Humans Gential tract cancers, including invasive carcinomas of the cervix
Major Families of Animal Major Families of Animal
VirusesViruses DNA Containing Viruses
Papovaviridae, continuedHuman Papilloma Viruses (HPV) 1-34Genus Polyomavirus
Subfamily Host Symptoms in Humans
BK virus Humans Isolated from the urine of renal transplant patients
JC virus Humans Isolated from the brains of patients with progressive multifocal leukoencephalopathy
Lymphotrophic papovavirus (LPV)
African green monkey, Humans (?)
Multiples only in monkey and human B lymphoblasts. About 30 percent of humans have antibody against it.
Major Families of Animal Major Families of Animal
VirusesViruses DNA Containing Viruses
ParvoviridaeGenus Parvovirus
Subfamily Host Symptoms in Humans
Parvovirus-like agent (PLVA) Strain B19
Humans Erythemia infectiosum (fifth disease); linked to aplastic crisis in hemolytic anemia/sickle cell anemia
Lu-111 Humans No known disease
Genus Dependovirus Adeno-associated virus
(AAV)
Serotypes 1,2,3,5 Humans Antibodies very prevalent; no known symptoms
Major Families of Animal Major Families of Animal
VirusesViruses RNA Containing Viruses
Picornaviridae, continuedGenus EnterovirusHuman enteroviruses
Subfamily Host Symptoms in Humans
Coxsackle virus B6 serotypes
Humans, mouse Primarily fatty tissue and CNS damage; pleurodynia (Bornholm disease); aseptic meningitis; paralysis; severe systemic illness of newborns
ECHOviruses (enteric cytopathogenic human orphan) 32 serotypes
Humans Paralysis, diarrhea, aseptic meningitis
Human enterovirus 72 (hepatitis A virus)
Humans Infectious hepatitis, jaundice
Major Families of Animal Major Families of Animal
VirusesViruses RNA Containing Viruses
Picornaviridae, continuedGenus
Cardiovirus
Subfamily Host Symptoms in Humans
Encephalomyocarditis virus (EMC) (Several very closely
related viruses including
mengovirus, ME virus, EMC virus, MM virus and Columbia
SK virus)
Primarily mouse, various other species,
including humans
Mild febrile illness
Genus Rhinovirus
Human rhinoviruses
113 serotypes
Humans Common cold, bronchitis, croup, bronchopheumonia
Major Families of Animal Major Families of Animal
VirusesViruses RNA Containing Viruses
TogaviridaeGenus Alphavirus(mosquito-
borne)
Subfamily Host Symptoms in Humans
Eastern equine encephalitis (EEE)
Birds Encephalitis: Frequently Fatal
Semliki forest virus Monkeys Encephalitis (rare)
Sindbis Monkeys Fever, rash, arthritis
Chikungunya Monkeys Myositis-arthritis
Ross river virus Mammals Fever, rash, arthralgia
Venezuelan equine encephalitis (VEE)
Rodents Encephalitis
Western equine encephalitis (WEE)
Birds Encephalitis
Major Families of Animal Major Families of Animal
VirusesViruses RNA Containing Viruses Togaviridae, continued
Genus Rubivirus
Subfamily Host Symptoms in Humans
Rubella virus Humans Severs deformities of fetuses in first trimester of pregnancy
Major Families of Animal Major Families of Animal
VirusesViruses RNA Containing Viruses
FlaviviridaeMosquito-borne
Subfamily Host Symptoms in Humans
Yellow Fever Monkey Hemorrhagic fever, hepatitis, nephritis, often fatal
Dengue virus4 serotypes
Humans Fever, arthralgia, rash
West Nile fever Birds Fever, arthralgia, rash
St. Louis encephalitis Birds Encephalitis
Japanese encephalitis Birds Encephalitis; frequently fatal
Murray Valley encephalitis
Birds Encephalitis
Major Families of Animal Major Families of Animal VirusesViruses
RNA Containing Viruses Flaviviridae,continued
Tick-borne
Subfamily Host Symptoms in Humans
Central European tick-borne
encephalitis (biphasic
meningoencephalitis)
Rodents, hedgehog Encephalitis
Far Eastern tick-borne encephalitis (Russian spring-
summer encephalitis, RSSE)
Rodents Encephalitis
Kyasanur forest virus Rodents Hemorrhagic fever
Louping III Sheep Encephalitis
Powassan Rodents Encephalitis
Omsk hemorrhagic fever virus
Mammals Hemorrhagic fever
Major Families of Animal Major Families of Animal
VirusesViruses RNA Containing Viruses
CoronaviridaeAntigenic Group
I
Subfamily Host Symptoms in Humans
Human coronavirus
Strain HCV-229E
Humans Upper respiratory disease
Antigenic Group II
Human coronavirus
Strain HCV-oc43
Humans Upper respiratory disease
Major Families of Animal Major Families of Animal
VirusesViruses RNA Containing Viruses
RhabdoviridaeGenus
Lyssavirus
Subfamily Host Symptoms in Humans
Rabies virus All warm-blooded animals
Encephalitis, almost invariably fatal
FiloviridaeSubfamily Host Symptoms in
Humans
Marbug virus Humans Acute hemorrhagic fever; frequently fatal
Ebola virus Humans Acute hemorrhagic fever; frequently fatal
Major Families of Animal Major Families of Animal
VirusesViruses RNA Containing Viruses
ParamyxoviridaeGenus
Paramyxoviridae
Subfamily Host Symptoms in Humans
Parainfluenza virus type 1 Sendai virus
(hemagglutinating virus of Japan [HVJ])
Humans, pig, mouse Croup, common cold syndrome
HA-2 (hemadsorption virus)
Humans Mild respiratory disease
Parainfluenza viruses types 2-5 Numerous
strands including HA-1, SV5
Humans and other animals
Respiratory tract infections
Mumps Human Parotitis, orchitis, meningoencephalitis
The family of Paramyxoviridae contains viruses that induce a wide range of distinct clinical illnesses in humans:-
These include measles virus, which in rare instances is followed by subacute sclerosing panencephalitis (SSPE);
mumps virus, which has symptoms of parotitis, orchitis and encephalitis, and the parainfluenza viruses which are
respiratory pathogens .
Paramyxoviruses
Virions are enveloped and enclose a helical nucleocapsid containing single-stranded RNA. Most virions are roughly spherical(about 200nm in diameter) but they can be much larger and more pleomorphic. The virus envelope is a lipid bilayer,studded with virus encoded glycoproteinswhich have properties of haemagglutinationand fusion (the F protein).
Major Families of Animal Major Families of Animal
VirusesViruses RNA Containing Viruses
Paramyxoviridae, continuedGenus
Morbillivirus
Subfamily Host Symptoms in Humans
Measles Humans Measles; chronic degeneration of the central nervous system (SSPE)
Genus Pneumovirus
Respiratory syncytial virus (RSV)
Humans Pneumonia and bronchiolitis in infants and children, common cold syndrome
Major Families of Animal Major Families of Animal
VirusesViruses RNA Containing Viruses
Orthomyxoviridae, continuedGenus Influenzavirus
Subfamily Host Symptoms in Humans
Equine subtypesInfluenza virus type B
Human subtypesB0 1940-1945B1 1945-1955B2 1962-1964
B3 1962-present (Taiwan)
Humans
Acute respiratory diseaseAcute respiratory diseaseAcute respiratory diseaseAcute respiratory disease
Influenza virus type C(possible separate
genus)
Humans Respiratory disease
Major Families of Animal Major Families of Animal
VirusesViruses RNA Containing Viruses
BunyaviridaeGenus Bunyavirus(16 serogroups)
Subfamily Host Symptoms in Humans
Bunyamwera Mammals Fever, rash
California encephalitis group including La Crosse, Lumbo and
snowshoe hare virus
Mammals Encephalitis
Genus Phlebovirus
Sandfly fever virus Sandfly, mammals Facial erythema
Rift Valley fever virus Humans, sheep, cattle Fever, arthralgia, retinitis
Major Families of Animal Major Families of Animal
VirusesViruses RNA Containing VirusesBunyaviridae, continued
Genus Nairovirus
Subfamily Host Symptoms in Humans
Crimean-Congo hemorrhagic fever
(CCHF)
Mammals Hemorrhagic fever
Unclassified Bunyavirus
Hantaan virus (Korean hemorrhagic
fever)
Rodents Hemorrhagic fever with renal syndrome
Major Families of Animal Major Families of Animal
VirusesViruses RNA Containing Viruses
ArenaviridaeSubfamily Host Symptoms in
HumansLymphocytic
choroiomeningitis virus (LCM)
Mouse, Humans Latent infection in mice; may produce fatal meningitis in other species, including humans
Tacaribe virus complex
Several viruses including Argentinian (Junin) hemorrhagic
fever & Bolivian (Machupo)
hemorrhagic fever
Rodents, Humans
Hemorrhagic fever; frequently fatal
Lassa virus Rodents Hemorrhagic fever; frequently fatal
RetrovirusesRetroviruses
Life Cycle
HIVHIV
AIDsAIDs
www.openthefuture.com/images/retrovirus.jpeg
Retrovirus – General Picture
Three Genes: GAG = GROUP ANTIGENPOL = POLYMERASE ENV = ENVELOPE
1724
76
10 –Protease
32 – Int
66/51 –RT
http://student.bmj.com/back_issues/1198/data/1198ed1.htm
2 copies RNA
HIV Structure
Retroviral Life Cycle
Viral
Reverse Transcription
Viruses and Cancer
• No oncogenes noted, yet these viruses cause leukemias and lymphomas
• Their names were once RNA tumor viruses and RNA leukemia viruses
Proviral DNA inserts “randomly”.
Long terminal repeats (LTR) containing 3’5’ sequences act as transcriptional “Promoters”.
Since these LTRs are identical and since they are locatedat each end of the proviral DNA, they can promote viral gene expression as well as “adjacent” gene expression.
LTR LTR
Growth Factors
Receptors
Intracellular Signalling molecules
Transcription Factors
Proto-oncogenes and oncogenes related to cellular receptors and
signal transduction intermediates
• Receptors– EGF (epidermal growth factor)– Neu (neuroblastoma)
• Signal Transduction Intermediates– Insulin signaling intermediates– “ras”
Oncogene Receptor Proteins
• Creation of oncogenes from proto-oncogenes that encode cell-surface receptors. In the example diagrammed here, the neu-oncogene arises from a mutation that alters a single amino acid (valine to glutamine) in the transmembrane region, somehow making the protein constitutively active as a kinase. In the other example, the receptor is for EGF; the oncogene arises by loss of the coding region for the EGF-binding domain.
From Molecular and Cell Biology, Lodish, et al., 1995
Erbitux
www.openthefuture.com/images/retrovirus.jpeg
HIV (Retrovirus) – General Picture
Retroviral Life Cycle
172476
10 – Protease
32 – Int
66/51 – RT
http://student.bmj.com/back_issues/1198/data/1198ed1.htm
2 copies RNA
HIV Structure
www.stanford.edu/.../2005gongishmail/HIV.html
HIV Life Cycle
Attachment
CD4 Normal Function
• CD4 is a co-receptor that assists the T cell receptor (TCR) with an antigen presenting cell. Using its portion that resides inside the T cell, CD4 amplifies the signal generated by the TCR by recruiting an enzyme known as the tyrosine kinase, lck, which is essential for activating many molecules involved in the signaling cascade of an activated T cell. CD4 also interacts directly with MHC Class II molecules on the surface of the antigen-presenting cell using its extracellular domain.
CD4 (cluster of differentiation 4) is a gycoprotein found on the surface of immune cells such as T helper cells, monocytes, macrophages, and dendritic cells. It was discovered in the late 1970s and was originally known as leu-3 and T4 (after the OKT4 monoclonal antibody that reacted with it) before being named CD4 in 1984. In humans, the CD4 protein is encoded by the CD4 gene.
CD4+ T helper cells are WBCs that are an essential part of the human immune system. They are often referred to as CD4 cells, T-helper cells or T4 cells. They are called helper cells because one of their main roles is to send signals to other types of immune cells, including CD8 killer cells. CD4 cells send the signal and CD8 cells destroy and kill the infection or virus. If CD4 cells become depleted, for example in untreated HIV infection, or following immune suppression prior to a transplant, the body is left vulnerable to a wide range of infections that it would otherwise have been able to
fight.
Wikipedia Free Encyclopedia
Attachment – up close
CD4
CCR5
gp41
Emini, E. & Koff, W.C. Developing an AIDS vaccine; Need, Uncertainly, Hope. Science, 304: 1913, 2004
gp120
From the following article:HIV drug development: the next 25 years
Charles FlexnerNature Reviews Drug Discovery 6,
959-966 (December 2007)
HIV Life Cycle
HIV Tropism
HIV tropism refers to the cell type that the human immunodeficiency virus (HIV) infects and replicates in. HIV tropism of a patient's virus is measured by the Trofile assay.HIV can infect a variety of cells such as CD4+ helper T-cells and macrophages that express the CD4 molecule on their surface. HIV-1 entry to macrophages and T helper cells is mediated not only through interaction of the virion envelope glycoproteins (gp120) with the CD4 molecule on the target cells but also with its chemokine co-receptors.
Macrophage (M-tropic) strains of HIV-1, or non-syncitia-inducing strains (NSI) use the beta-chemokine receptor CCR5 for entry and are thus able to replicate in macrophages and CD4+ T-cells. These strains are now called R5 viruses. The normal ligands for this receptor, RANTES, macrophage inflammatory protein (MIP)-1-beta and MIP-1-alpha, are able to suppress HIV-1 infection in vitro. This CCR5 coreceptor is used by almost all primary HIV-1 isolates regardless of viral genetic subtype.
T-tropic isolates, or syncitia-inducing (SI) strains replicate in primary CD4+ T-cells as well as in macrophages and use the alpha-chemokine receptor, CSCR4, for entry. These strains are now called X4 viruses. The alpha-chemokine, SDF-1, a ligand for CSCR4, suppresses replication of T-tropic HIV-1 isolates. It does this by down regulating the expression of CXCR4 on the surface of these cells.Viruses that use only the CCR5 receptor are termed R5, those that only use CXCR4 are termed X4, and those that use both, X4R5. However, the use of coreceptor alone does not explain viral tropism, as not all R5 viruses are able to use CCR5 on macrophages for a productive infection.[1]
CD4+ T cell
Penetration
Penetration – con’t.
Reverse transcription
Integration
Transcription
Translation of viral mRNAs into viral precursor proteins
Envelope Precursor Protein Processing
Gag and Gag-Pol Precursor Assembly with viral RNA
Viral Assembly – con’t.
Virus release and maturation
160Cellular protease
ViralProtease
ViralProtease
Polypeptide cleavage
Viral Protease
Polypeptide cleavage
Polypeptide cleavage
Polypeptide cleavage
Viral ‘Gag’ Proteins (p17, p24, p9, p6)
Viral ‘Pol’ proteins(Reverse Transcriptase,
RNAse, Integrase, Protease)
Viral ‘Env’ proteins(gp120, gp41)
A human immunodeficiency viral particle is seen budding from the infected cell A human immunodeficiency viral particle is seen budding from the infected cell surfacesurface
at the top, with a complete viral particle at bottom in this high magnification at the top, with a complete viral particle at bottom in this high magnification electronelectron
micrograph. micrograph.
Human immunodeficiency virus, viral particles Human immunodeficiency virus, viral particles are seen at low magnification adjacent toare seen at low magnification adjacent to
the cell surface in this electron micrograph. the cell surface in this electron micrograph.
Human immunodeficiency viralHuman immunodeficiency viral particles are seen at medium magnification in thisparticles are seen at medium magnification in this electron micrograph. Note the central core and the outer envelope. electron micrograph. Note the central core and the outer envelope.
HIV Life Cyclewith Drug Targets
Atripla (Sustiva/Viread/Emtriva) – Approved July 11th, 2006
DESCRIPTIONREYATAZ® (atazanavir sulfate) is an
azapeptide inhibitor of HIV-1 protease.The chemical name for atazanavir sulfate is
(3S,8S,9S,12S )-3,12-Bis(1,1-dimethylethyl)-8-hydroxy-4,11-dioxo-9-(phenylmethyl)-
6-[[4-(2-pyridinyl)phenyl] methyl]-2,5,6,10,13-pentaazatetradecanedioic acid
dimethyl ester, sulfate (1:1). Itsmolecular formula is C38H52N6O7•H2SO4, which corresponds to a molecular weight of
802.9 (sulfuric acid salt). The free basemolecular weight is 704.9. Atazanavir sulfate
has the following structural formula:
Mechanism of ActionAtazanavir (ATV) is an azapeptide HIV-1 protease inhibitor (PI). The compound
selectively inhibits the virus-specific processingof viral Gag and Gag-Pol polyproteins in HIV-1
infected cells, thus preventing formation of mature virions.
Reyataz is manufactured by Bristol-Myers Squibb and was approved for the treatment
of HIV by the U.S. FDA in 2006.
DESCRIPTIONFUZEON (enfuvirtide) is an
inhibitor of the fusion of HIV-1 with CD4+ cells. Enfuvirtide is a
linear36-amino acid synthetic
peptide with the N-terminus acetylated and the C-terminus
is a carboxamide.It is composed of naturally
occurring L-amino acid residues.
Mechanism of ActionEnfuvirtide interferes with the entry of HIV-1 into cells by inhibiting fusion of viral
and cellularmembranes. Enfuvirtide binds
to the first heptad-repeat (HR1) in the gp41 subunit of
the viralenvelope glycoprotein and
prevents the conformational changes required for the
fusion of viraland cellular membranes.
2006
NYSE | BMY 24.79 | +0.23 | 1:30 PM EDT | 17 Jul 2006 Top Story
FDA ApprovesATRIPLA™ (efavirenz 600 mg/ emtricitabine 200 mg/
tenofovir disoproxil fumarate 300 mg), The First Once-Daily Single Tablet Regimen For Adults With HIV-1 Infection
Princeton, NJ and Foster City, CA (July 12, 2006) -- Bristol-Myers Squibb Company (NYSE: BMY) and Gilead Sciences, Inc. (Nasdaq: GILD) today announced the U.S. Food and Drug Administration (FDA) has granted approval of ATRIPLA™ (efavirenz 600 mg/ emtricitabine 200 mg/ tenofovir disoproxil fumarate 300 mg) for the treatment of HIV-1 infection in adults. ATRIPLA is the first-ever once-daily single tablet regimen (STR) for HIV intended as a stand-alone therapy or in combination with other antiretrovirals. The product combines SUSTIVA® (efavirenz), manufactured by Bristol-Myers Squibb, and Truvada® (emtricitabine and tenofovir disoproxil fumarate), manufactured by Gilead Sciences. Truvada itself is a fixed-dose product that contains two of Gilead's anti-HIV medications, Viread® (tenofovir disoproxil fumarate) and Emtriva® (emtricitabine), in a single once-daily tablet for use as part of combination therapy. ATRIPLA will be available in the United States within seven business days.
Maraviroc – CCR5 blocker• Pfizer Gets the Nod from FDA for First-in-Class HIV Drug • Aug 7 2007, 12:53 PM EST
• FDA has given Pfizer the go-ahead for its first-in-class HIV medication, maraviroc. The company expects that the drug, which will be sold under the trade name Selzentry, will be available in the U.S. by the middle of September.
• • After receiving a unanimous vote of support from an FDA advisory committee in
April, the agency stalled by sending Pfizer an approvable letter in June. The final sanction of the drug drove Pfizer’s shares up 60 cents, or 2.6%, to $24.11 at 4:01 p.m. in New York Stock Exchange composite trading. Pfizer is awaiting approval from the EMEA and is submitting marketing applications to other regulatory bodies. On June 20, an EMEA advisory committee vouched in favor of maraviroc, which will be sold in the EU as Celsentri.
• • Rather than fighting HIV inside white blood cells, maraviroc prevents the virus from
entering uninfected cells by blocking the predominant route of entry, the CCR5 co-receptor. Among patients who have previously received HIV medications, approximately 50% to 60% have circulating CCR5-tropic HIV-1, according to the FDA.
• The agency granted accelerated approval to Selzentry in combination with other antiretroviral drugs in adults with CCR5-tropic HIV-1 who have been treated with other HIV medications and who have evidence of elevated levels of HIV in their blood. A diagnostic test is required to confirm whether a patient is infected with CCR5-tropic HIV-1, which is also known as R5 virus.
• Longer-term data will be required before the FDA can consider traditional approval for Selzentry, Pfizer notes.
Integrase Inhibitor
• Merck & Co. Gets the Green Light for HIV Treatment in EU• Dec 21 2007, 12:38 PM EST
• The European Union Commission approved Merck & Co. first-in-class HIV therapy Isentress® (Raltegravir). The drug will be marketed for use in combination with other antiretroviral products against HIV-1 infection in treatment-experienced adults with evidence of HIV-1 replication despite ongoing antiretroviral therapy (ART).
• The commission’s decision is applicable to the 27 member states of the EU.
Separate national licenses will also be issued in European Economic Area member states Iceland and Norway, according to Merck, also known as Merck Sharp & Dohme (MSD) in some countries.
• Isentress is already sanctioned in North America. MSD says that it is also
moving forward with filings in other countries around the world. • Isentress is the first approved integrase inhibitor. It inhibits the insertion of
the HIV DNA into human DNA by the integrase enzyme. Inhibiting integrase from performing this essential function blocks the ability of the virus to replicate and infect new cells. Other drugs target the other two enzymes critical to HIV replication, protease and reverse transcriptase. Pfizer’s Maraviroc, on the other hand, which received FDA approval in August, blocks the CCR5 co-receptor.“Raltegravir is an important new advancement in the treatment of HIV because it is the first therapy in a new class of drugs that attacks the virus in a completely different way from other available medicines,” notes Ken Frazier, evp and president, global human health, Merck.
Atripla (Sustiva/Viread/Emtriva) – Approved July 11th, 2006
Drugs in Development Nature NewsNature Reviews Drug Discovery 6, 258-259 (April 2007)
Approved
HIV Life Cycle
Group 3
Group 1
Group 2
www.stanford.edu/.../2005gongishmail/HIV.html
HIV Life Cycle
Other HIV Proteins• TAT - Transactivator of HIV gene expression
• One of two essential viral regulatory factor• Two forms; 72 aa and 86 aa.• Nucleus/nucleolus location• Binds TAR cis element in viral RNA• Activates transcription; one means is by
preventing the 5’ LTR polyadenylation signal from causing premature termination of transcription.
• First eukaryotic transcription factor known to interact with RNA rather than DNA
Other HIV Proteins
• REV
– The second necessary regulatory HIV protein– 19kDA phospho-protein– Localized in nucleus/nucleolus and cytoplasm– Binds to RRE in viral RNAs and promotes viral
nuclear export and stability.– One of first proteins produced in infected cell– Encoded by doubly spliced viral mRNA– Helps viral mRNA to get out of nucleus.
Other HIV Proteins
• VIF - viral infectivity factor
– Basic protein, 23 kDa.– Promotes infectivity but not production of
viral particles– In absense of VIF, viral particles are
defective– Cytoplasmic protein– Molecular mechanism unknown
Other HIV Proteins
• VPR; VPU; NEF; VPX
•Now, What about AIDS??
CDC Classification System for HIV-Infected Adults and Adolescents
CD4 Cell Categories
A. Asymptomatic, Acute HIV, or PGL
B. Symptomatic Conditions, #* not
A or C
C. AIDS-Indicator Conditions*
(1) ≥500 cells/µL A1 B1 C1
(2) 200-499 cells/µL
A2 B2 C2
(3) <200 cells/µL A3 B3 C3
Clinical Categories
Key to abbreviations: CDC = U.S. Centers for Disease Control and Prevention;
PGL = persistent generalized lymphadenopathy.
# For symptomatic conditions, see Table 2 .
* For AIDS-indicator conditions, see Table 3 . HIV Classification: CDC and WHO Staging Systems
July 2006
Table 2. CDC Classification System:
Category B Symptomatic Conditions
• Category B symptomatic conditions are defined as symptomatic conditions occurring in an HIV-infected adolescent or adult that meet at least 1 of the following criteria:
– a) They are attributed to HIV infection or indicate a defect in cell-mediated immunity. – b) They are considered to have a clinical course or management that is complicated by HIV
infection. • Examples include, but are not limited to, the following:• Bacillary angiomatosis • Oropharyngeal candidiasis (thrush) • Vulvovaginal candidiasis, persistent or resistant • Pelvic inflammatory disease (PID) • Cervical dysplasia (moderate or severe)/cervical carcinoma in situ • Hairy leukoplakia, oral • Idiopathic thrombocytopenic purpura • Constitutional symptoms, such as fever (>38.5°C) or diarrhea lasting >1 month • Peripheral neuropathy • Herpes zoster (shingles), involving ≥2 episodes or ≥1 dermatome
Table 3. CDC Classification System: Category C
AIDS-Indicator Conditions
• Bacterial pneumonia, recurrent (≥2 episodes in 12 months) • Candidiasis of the bronchi, trachea, or lungs • Candidiasis, esophageal • Cervical carcinoma, invasive, confirmed by biopsy • Coccidioidomycosis, disseminated or extrapulmonary • Cryptococcosis, extrapulmonary • Cryptosporidiosis, chronic intestinal (>1-month duration) • Cytomegalovirus disease (other than liver, spleen, or nodes) • Encephalopathy, HIV-related • Herpes simplex: chronic ulcers (>1-month duration), or bronchitis, pneumonitis, or esophagitis • Histoplasmosis, disseminated or extrapulmonary • Isosporiasis, chronic intestinal (>1-month duration) • Kaposi sarcoma • Lymphoma, Burkitt, immunoblastic, or primary central nervous system • Mycobacterium avium complex (MAC) or M kansasii , disseminated or extrapulmonary • Mycobacterium tuberculosis , pulmonary or extrapulmonary • Mycobacterium , other species or unidentified species, disseminated or extrapulmonary • Pneumocystis jiroveci (formerly carinii ) pneumonia (PCP) • Progressive multifocal leukoencephalopathy (PML) • Salmonella septicemia, recurrent (nontyphoid) • Toxoplasmosis of brain • Wasting syndrome due to HIV (involuntary weight loss >10% of baseline body weight) associated with either
chronic diarrhea (≥2 loose stools per day ≥1 month) or chronic weakness and documented fever ≥1 month
Replication
The replication process is catalyzed by an enzyme; DNA dependent DNA polymerase
2-deoxy Thymidine and AZT
Zidovudine or azidothymidine (AZT) 2-deoxythymidine
Dideoxynucleoside HIV Drugs
AZT – RetrovirddI – videxddC – Hividd4T – Zerit3TC - Epivar
Dideoxynucleotides
HIV Life Cycle
Colored slide: H-91
Hiv Life Cycle
http://www.youtube.com/watch?v=qYUnDzDO-Ic
NRTI
NNRTI http://www.youtube.com/watch?v=RUUyd5bE9vQ&NR=1
Protease Inhibitors http://www.youtube.com/watch?v=yYZgFndtfzc&NR=1
HAART – Highly Active Anti Retroviral Therapy
http://www.youtube.com/watch?v=RO8MP3wMvqg
Links to videos.
Definitions
• Tumors - “Un-controlled” cellular growth that arises with great frequency especially in older animals and humans.
• Transformation - The process whereby “normal” cells become altered or transformed and acquire the ability to form tumors.
Definition: Cancer Cancer: An abnormal growth of cells which tend to proliferate in an uncontrolled way and, in some
cases, to metastasize (spread).
• Cancer is not one disease. It is a group of more than 100 different and distinctive diseases.
• Cancer can involve any tissue of the body and have many different forms in each body area. Most cancers are named for the type of cell or organ in which they start. If a cancer spreads (metastasizes), the new tumor bears the same name as the original (primary) tumor.
• • The frequency of a particular cancer may depend on gender. While skin cancer is the most common
type of malignancy for both men and women, the second most common type in men is prostate cancer and in women, breast cancer.
• • Cancer frequency does not equate to cancer mortality. Skin cancers are often curable. Lung cancer is
the leading cause of death from cancer for both men and women in the United States today.
• Benign tumors are NOT cancer; malignant tumors are cancer. Cancer is NOT contagious.
• Cancer is the Latin word for crab. The ancients used the word to mean a malignancy, doubtless because of the crab-like tenacity a malignant tumor sometimes seems to show in grasping the tissues it invades. Cancer may also be called malignancy, a malignant tumor, or a neoplasm (literally, a new growth).
Cancer Description, con’t.
Cancer (medical term: malignant neoplasm) s a class of diseases in which a group of cells display uncontrolled growth (cell division beyond the normal limits), invasion (intrusion on and destruction of adjacent tissues), and sometimes metastasis (spread to other locations in the body via lymph or blood).
These three malignant properties of cancers differentiate them from beign tumors, which are self-limited, do not invade or metastasize. Most cancers form a tumor but some, like leukemia, do not. The branch of medicine concerned with the study, diagnosis, treatment, and prevention of cancer is oncology.
Cancer may affect people at all ages, even fetuses but the risk for most varieties increases with age. Cancer causes about 13% of all deaths. According to the American Cancer Society, 7.6 million people died from cancer in the world during 2007. Cancers can affect all animals.
Nearly all cancers are caused by abnormalities in the genetic material of the transformed cells. These abnormalities may be due to the effects of carcinogens, such as tobacco smoke, radiation, chemicals, or infectious agents. Other cancer-promoting genetic abnormalities may be randomly acquired through errors in DNA replication, or are inherited, and thus present in all cells from birth. The heritability of cancers are usually affected by complex interactions between carcinogens and the host's genome. New aspects of the genetics of cancer pathogenesis, such as DNA methylation, and microRNAs are increasingly recognized as important.
Definitions - Oncology
• Oncology - The scientific study of tumors.• Oncogene - Cancer causing gene; derived
from Greek word meaning a bulk or mass.• Proto-oncogenes - Cellular genes know to
be progenitors of oncogenes.• Oncoproteins - Protein products encoded
by oncogenes that transform cells from normal to malignant.
How many genes are involved in breast cancer?
• Next year marks the 10th anniversary of the mapping of the breast-ovarian cancer susceptibility gene BRCA1 to chromosome 17 [1], and the identification of the TP53 gene as the cause of the Li-Fraumeni syndrome [2]. As a result of these discoveries, and the subsequent discovery of other breast cancer susceptibility genes, notably BRCA2 [3], inherited susceptibility has risen from relative obscurity to have a central role in breast cancer research. Understanding the biological mechanisms that underlie the susceptibility genes has become a major research activity, and of course mutation testing is now a major part of clinical genetics practice, with the prospects for improved prevention and treatment of the disease in women at high risk. Thus, it is natural to ask whether there are any more genes to find, what their characteristics might be and how we might go about finding them.
• Of the five genes that are, beyond any reasonable doubt, breast cancer predisposition genes, the BRCA1 and BRCA2 genes are the most important numerically (Table 1). Mutations in these genes, which cause high risks of breast and ovarian cancer, account for almost all the multiple case breast-ovarian cancer families, and probably around 2% of breast cancer cases overall [4,5]. Germline mutations in the TP53 gene predispose to a spectrum of cancers known as the Li-Fraumeni syndrome, including childhood sarcomas and brain tumours, as well as early-onset breast cancer [2]; and germline mutations in the PTEN gene are responsible for Cowdens syndrome, of which breast cancer is a major feature [6]. Mutations in a fifth gene, the androgen receptor gene, are known to pre-dispose to breast cancer in men [7].
Reference to previous slide.
• Breast Cancer Res. 1999; 1(1): 14–17.
• Published online 1999 August 23. doi: 10.1186/bcr6.
• PMCID: PMC138504
• Copyright © 1999 Current Science Ltd
• How many more breast cancer predisposition genes are there?
• Douglas F Easton1 1Cancer Research Campaign (CRC) Genetic Epidemiology Unit, Strangeways Research Laboratories, Worts Causeway, Cambridge, UK.
• Douglas F Easton: [email protected]
• Received July 16, 1999; Accepted July 22, 1999.
Colored slide: H-72
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