RNA Viruses

of Animals

Viral Classification

Taxonomy Order (-viridae) Family (-viridae) Subfamily (-virinae) Genus (-virus) Species

Group III (ds) IV (+ss) V (-ss)

RNA Virions Cytoplasm:

Replication Biosynthesis

Helical capsid Most enveloped

with spikes NA

Double sense Single sense (+ / -) 2 single sense (+)

Viral Entry into Cells

Group III: dsRNA Reoviridae

REOVIRIDAE

REO=Respiratory Enteric Orphan Virus

Non-enveloped Icosahedral RNA ds Segmented Human Diseases

Rotavirus Coltivirus

Rotavirus World wide infection Fecal-oral spread Incubation: 1-3 days Diarrhea Children Diagnosis

ELISA Latex Agglutination

Prevention Hygiene Water sanitation

Coltivirus Colorado Tick

Fever Disease

• Acute• Myalgia• Photophobia• Rash• Hemorrhage

Tick vector Rodent reservoir

RNA ss (+); (-); & retro-

Group IV: +ssRNA nonenveloped Picornavirus

Rhinovirus Enterovirus Hepatovirus

Calicivirus Astrovirus Hepevirus

Hepevirus (formerly calcivirus)

+ss RNA nonenveloped Icosahedral Fecal-oral Domestic pig

reservoir Developing

countries/sanitation Hepatitis E

(enteric hepatitis)

ASTROVIRIDAE Astro = Star Nonenveloped +ssRNA 7 Human Serotypes Diarrhea Treatment

Supportive

CALICIVIRIDAE

Calicus Cup shaped Indentations

Non-enveloped Icosahedral Linear ss + RNA Human Diseases

Norwalk Virus(Norovirus)

Calicivirus

Norwalk Virus Summer diarrhea Epidemic Gastroenteritis V/D Institutions ID virus in stool 90% of viral

diarrheas

PICORNAVIRIDAE Pico = small Nonenveloped Icosahedral RNA + ss Human Diseases

Enterovirus• Polio• Coxsackie A , B• ECHO

Rhinovirus Hepatovirus

Rhinovirus

Common cold virus: 50%

Transmission: inhalation Incubation: 1-3 days Symptoms

Sore throat Mucopurulent nasal

discharge Complications

predispose to secondary bacterial infections

Hepatovirus: Hepatitis A Infectious Hepatitis Milder disease than

Hepatitis B No chronic form Fecal-oral Incubation: 2-5 weeks Virus excreted in stool Resistant to

disinfection Dx: IgM

Enterovirus

Disease Groups Poliovirus Coxsackie A, B Echovirus

Fecal-oral Cytolytic

GI mucosa Lymphatic tissue

Echovirus ECHO=

Enteric Cytopathic Human Orphan

Fecal-oral route Disease

Meningitis Paralysis URTI Myocarditis Fever Rashes Orchitis

Coxsackie A and B Fecal-oral Disease

Coxsackie A• Skin Rashes• Herpangina

• Mouth• Pharynx

• Hand/Foot/Mouth• Conjunctivitis• +/- DM Type I cause

Coxsackie B• Myocarditis• Meningitis• URTI• Paralysis

Poliomyelitis 3 serotypes (Type 1 disease) Transmission: fecal-oral Throat ->LN->Ileum->Blood-> CNS Phases

Asymptomatic: 90% Minor Polio Non-paralytic Paralytic: 2-3%, causes 75% of paralysis

Dx: virus in feces, secretions Prevention: Vaccine

Salk (IPV, killed) Sabin (OPV, modified live)

Poliovirus

Post Polio syndrome

BulbarPoliomyelitis

Group IV:+ssRNA enveloped

Togavirus Flavivirus Coronavirus

CORONAVIRIDAE Corona = crown Enveloped Helical Linear RNA + ss Respiratory droplet Human Diseases

Common cold (20%)

SARS

Severe Acute Respiratory Syndrome (SARS)

Respiratory Droplet Direct Indirect

2-10 day incubation Cough->Pneumonia Stable in environment

for days Dx: PCR Tx: supportive Prevention

avoid contact disinfect

TOGAVIRIDAE Toga = coat Spiked envelope Icosahedral Linear ss+RNA ~Arthropod vector Human diseases

Encephalitis • (VEE, WEE, EEE)

Rubella

Encephalitis: VEE, WEE, EEE

Rodent: VEE

all

Togavirus: Rubella Rubella

German Measles Respiratory Droplet 2-3 week incubation Rash: 3 days

• Facial• Spreads to body• Changes hourly

Complications• Adults

• Arthritis• Encephalitis

• Congenital defects• Nervous• Heart• Blindness

Prevention: MMRRubivirus

FLAVIVIRIDAE Flavus = yellow Enveloped Helical Linear RNA ss + Human Diseases

Hepatitis Encephalitis Hemorrhagic Fever

Flavivirus Hepatitis C

• HCV• Non A non B

Endemic Parental

• Blood• Needles• Organs

6-8 week incubation Mild form Chronic

• Cancer• Liver failure

Dx:IgG, PCR Tx: Interferon

Flaviviridae Hepatitis

Yellow Fever• Liver / GI• Kidneys• Heart

Hepatitis G• Acute• Persistent• Co-infection with

Hepatitis C• Parental: blood

Encephalitis Japanese Complex Russian

spring/summer St. Louis

• Acute• Inflammatory• Vector: mosquito• 4-21 days

incubation

Flavivirus Encephalitis

Flavivirus West Nile Virus

Acute Febrile Hemorrhagic Vector: mosquito 3-14 days

incubation Dx: IgM, ELISA Tx: Supportive

Flavivirus: Dengue Fever Tropical Aedes mosquito Disease syndromes

Breakbone fever• Rash• Myalgia

Hemorrhagic fever• Reinfection• Hyperimmune

response

Group V: -ssRNA enveloped, segmented

Bunyvirus Orthomyxovirus Arenavirus

ARENAVIRIDAE Arenosus = sand (ribosomes) Enveloped Helical Segmented linear ss- RNA Rodent reservoir Human Disease

Hemorrhagic fever• Old world

• Lassa• Sabia• Junin

Lymphocytic choriomenigitis (LCM)

• New world arenavirus

Arenavirus Hepatitis D

Delta Agent Defective Incomplete ss RNA

• Viroid• Co-infection with HepB• Satellite virus

Enveloped Body fluid spread

BUNYAVIRIDAE Named after location

of first viral isolation Spiked, enveloped Helical Circular ss-RNA Human Disease

Arborvirus• Encephalitis• Respiratory• Hemorrhagic Fever

Rodent• Hanta Virus

Bunyavirus Hanta virus

Adult Respiratory Disease

1-3 weeks incubation Transmission: deer

mice Symptoms

• SOB• N/V• pain

Tx: supportive Prevention: rodent

control, disinfect

ORTHOMYXOVIRIDAE Myxo = mucus Spiked envelope

HA• hemaggluttinin• attach• Antigen number

NA• neuraminidase• through mucus• antigen number

Helical capsid 8 Segmented linear ss-

RNA Human Diseases

Influenza A Influenza B

-ssRNA

Orthomyxovirus Influenza

Range of symptoms from mild to severe

Droplet • Direct• Indirect

1-3 days incubation Reservoir: Humans Treatments

• Vaccination• Drugs

Complications• Recombinant due to

segmented RNA• Secondary bacterial

infections• Viral super infection with

Adenovirus

Influenza Treatments Inhibit Neuraminidase

Relenza (IN)Tamiflu (PO)

Antigenic drift: HA/NA mutationsAntigenic shift: genetic reassortment

Influenza Pandemics

Group V: -ssRNA enveloped, nonsegmented Paramyxovirus

Morbillivirus Parainfluenza Rubella RSV Nipahavirus

Rhabdovirus Filovirus

PARAMYXOVIRIDAE Similar to

Orthomyxoviruses Spiked Envelope

HA NA Fusion (F protein)

Helical Segmented linear ss –

RNA Human Diseases

Respiratory Epithelial

Paramyxovirus : Respiratory Parainfluenza

4 types (HPIV) Pediatric infection Symptoms

• Fever• Coryza• Barking cough

(Croup)• Airway obstruction

Droplet Tx: supportive

Paramyxovirus :Respiratory Respiratory

Syncytial Virus (RSV) Infants Pneumonia

• lower airways• Alveoli damaged

Symptoms• Cold like• Fever• Coryza• Cough• Wheeze• Dsypnea

Droplet Tx: supportive

Paramyxovirus: Epithelial Mumps

Glandular (Parotiditis) Droplet transmission 21 day incubation Inflammation Complications

• Encephalitis• Orchitis• Nephritis• Pancreatitis• Arthritis

IgM Tx: symptomatic Prevention: MMR

Rubulavirus

Mumps Pathogenesis

Paramyxovirus: Epithelial Measles (Rubeola)

Epithelial mucosal linings

• Skin -> rash• Respiratory• GI

Complications• Panencephalitis• Conjunctivitis

Droplet transmission 10-12 days incubation Desquamation Highly infectious Tx: symptomatic Prevention: MMR

Morbillivirus

RHABDOVIRIDAE Rhabdo = rod like Spiked, enveloped

Hemagglutin Helical -ssRNA Human Disease

Vesicular Stomatitis Rabies

Rhabdovirus Lyssa virus

Rabies• Encephalitis• Direct• 3-8 weeks incubation• Replication

• Local• CNS• Salivary

• Reservoir• Bats• K-9 / coyotes / foxes• Racoons• Skunks

• Clinical• Furious• Dumb

Tx: IgGPrevention: vaccination

FILOVIRIDAE Filo = filamentous Spiked, enveloped Helical Linear ss – RNA Pleomorphic shape

Filament, branched, U-shape, Circular

Gp epithelial receptors

Human Disease Acute Hemorrhagic

fevers• Marburg Virus• Ebola Virus

Marburg Fruit bat/green monkey Africa (Germany isolated Body fluid spread 3-9 day incubation Course

Rash Gi inflammation Liver failure Pancreatitis Hemorrhageshock MODSDeath

Ebola virus Africa Direct contact Acute hemorrhagic

fever 4-16 day incubation Symptoms

Fever V/D Rash Hemorrhage from all

open body cavities Death due to shock from

fluid and blood loss

RETROVIRIDAE Retro = reverse RNA dependent DNA polymerase (RT) Spiked envelope polyhedral 2 linear +ssRNA (diploid virus) Enzymes

Reverse transcriptase Protease Integrase

Human Diseases Deltaretrovirus HTLV: leukemia Lentivirus HIV: AIDS

Retroviridae Human T-Lymphocytic

Virus (HTLV-1) Adult T cell Leukemia Aggressive Tumor Latent Infiltrates

• Skin• brain

Transmission• Horizontal

• Blood• Sexual Intercourse

• Vertical• Breast milk

Retroviridae Human T-Lymphocytic

Virus (HTLV-2) B-Lymphocytes Hairy cell leukemia

• Slow growing• Middle aged men• Type of CLL

Signs• Bruising/bleeding• Swollen LN• Fatigue• Fevers

Human Immunodeficiency Virus

Ecological Groups Arboviruses

Arthropod borne viruses

Transmitted by• Insects• Mites• Ticks• Lice

Viral Families• Togavirus• Bunyaviridae• Rhabdovirus (some)• Arenavirus (some)• Reovirus (some)

Oncoviruses Cancer causing DNA related Viral Families

• Papovirus• Adenovirus• Parvovirus• Herpesvirus• Retrovirus

Zoonoses Disease that humans can acquire from

animals Viral examples

Marburg (monkeys) Pox (cow pox, pseudo-cowpox, monkey pox)

Rabies (warm blooded mammals)

Influenza A Lassa (rodents, bats) Hanta virus: pulmonary (rodents)

Viral Vaccines Live / Attenuated

Measles Mumps Rubella Polio (oral) Yellow Fever VZV

Killed / Viral Protein Hepatitis A Hepatitis B Rabies Polio (Salk)

Antiviral Chemotherapy Inhibits Viral DNA-dependent DNA polymerase

Herpes Inhibits DNA replication and transcription

Herpes Interferes with penetration or viral uncoating

Influenza A Inhibits translation of late mRNA

Smallpox Inhibits reverse transcriptase

Aids Inhibits Protein synthesis

Genital Warts

Questions?