Papilloma virusesPapilloma viruses&&

Polyoma virusesPolyoma viruses

HumanHuman Papilloma viruses (HPV)Papilloma viruses (HPV)

• DNA virus, double strand, circular, Icosahedral nucleocapsid, small size (45-55nm). No envelope

Human Papilloma virus (HPV) Human Papilloma virus (HPV)

• 70 different types (HPV-1 to HPV-70).

• It replicates only in the nucleus of epithelial cells. Infection occurs in skin and mucosal surfaces.

• HPV are species-specific.

HPVHPV

WartWart (Condylomata accuminata by HPV-2, -3, -10)

Common wart:

HPV-2, -3 and -10 (on knees and fingers)

plantar wart:

• HPV-1 • HPV-4

Genital wartsGenital warts

• HPV-6, -11, -16, -18 and- 32

• on penispenis, vulvavulva and perianalperianal regions.

• Can blossom into cauliflower-like protuberances.

• Transmission through sex contacts is increasing.

HPV & Cervical CancerHPV & Cervical Cancer

• The agents: The agents: HPV16 & HPV18 responsible for 70% of all cervical carcinoma.

• Starts with a flat area of dysplasia (visible as a white plaque).

• Cervical and anal-cervical carcinoma is associated with persistent HPV infections.

HPV Pathogenesis (1)HPV Pathogenesis (1)• It infects cells in the basal layers cells in the basal layers of the skin or

mucosa.

• Common period: 1-6 months1-6 months

• Viral antigen and infectious virus is produced when the cells begin to become squamifedsquamifed and keratinizedkeratinized.

• Several months later, the wart the wart may regressregress.

HPV Pathogenesis (2)HPV Pathogenesis (2)

• Cell mediated immunity Cell mediated immunity (CMI) responses are more important in recovery.

• In immunocompromisedimmunocompromised patients (e.g. post transplant), there may be warts as a result of reactivation.

DiagnosisDiagnosis

• Diagnosis is clinicalclinical

• HPV cannot be cultivatedcannot be cultivated in the laboratory

• SerologicalSerological tests are neither useful nor neither useful nor availableavailable

Treatment• Using keratolytic agents: - Salicylic acid (to soften and cause

desquamation of epithelium or horny layer of skin).

• Removing warts by surgery.

• Destruction of wart tissue by freezing with dry ice (solid CO2) or with liquid nitrogen.

• Using Podophyllin (a resinous powder obtained by precipitating an alcoholic tincture of the rhizome of American Mayapple)

Polyoma virusesPolyoma viruses

JC and BK virusesJC and BK viruses

Clinical findingsClinical findings

ParvovirusesParvoviruses

ParvovirusesParvoviruses - Unusual requirements for replication: either a

helper virus (a helper adenovirus) or rapidly dividing cells.

- The virus replicates when cell growth cycle is in “S” stage (when host DNA replication produces two identical sets of chromosomes.)

- Virus replication is in nucleus of the cell.

B19B19• A parvovirus replicating in erythroid precursor

cells, so the main place for virus replication is: fetal bone marrow and liver.

• Favorite receptor on erythrocytes: p Ag (Globoside).

• B19 can be found in blood and respiratory secretions.

• It can transmit from mother to embryo.

B19B19• A human virus which cannot pass to animals. • The virus interrupts the production of

erythrocytes in embryo causing sever anemia and abortion.

• Erythema infectiosum, (fifth disease), is the commonest clinical manifestation of B19 virus infection.

• In children (age 5-15) and sometimes adults (up to 30). 40-60% infections are asymptomatic.

Fifth disease Fifth disease (Erythema infectiosum)(Erythema infectiosum)

• First stage: 7-8 days after infection, a prodromal influenza-like

illness, characterized by headache, malaise, chills.

• Second stage: 17 to 18 days after infection, the development of a mild feverish

illness and a maculopapular rash. It starts with erythema of the cheeks (Slapped cheek) followed by a rash (resembling the rash of rubella) on the trunk and limbs. These symptoms disappeared 1-3 weeks.

Anemia Anemia & aplastic crisis aplastic crisis

• The virus infects erythroid precursor cells in the bone marrow and leads to anemia. Sever anemia in blood disorders (e.g. in Sickel cell anemia, Leukemia or hemolytic anemia)

• It leads to erythroid aplasia (Aplastic crisis) in patients with hemolytic anemia or immune deficiency, such as people with transplantation event.

• Anemia and aplastic crisis is self-limiting.

DiagnosisDiagnosis

• Detecting viral DNA in serum (PCR)

• A rise in parvovirus-specific IgM or IgG.• Bone marrow examination shows an absence of

erythroid precursors.

TransmissionTransmission

• B19 is anywhere, all through the year, different ages, sporadic or epidemic.• Spread through respiratory secretions,

vertical transmission from mother• Many cases are subclinical.

Control and treatmentControl and treatment

• There is no antiviral therapy or vaccine• Most infections are asymptomatic• The anemia is self-limiting, but blood

transfusion support is required until the bone marrow recovers.

• Antiserum decreases symptoms.• Sanitation