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Papilloma viruses & Polyoma viruses

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Presentation on theme: "Papilloma viruses & Polyoma viruses"— Presentation transcript:

1 Papilloma viruses & Polyoma viruses

2 Human Papilloma viruses (HPV)
DNA virus, double strand, circular, Icosahedral nucleocapsid, small size (45-55nm). No envelope

3 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.

4 They are transmitted by contacts (both direct and indirect).
HPV Some cause warts and some others are associated with cancer. They are transmitted by contacts (both direct and indirect).

5 Wart (Condylomata accuminata by HPV-2, -3, -10)
Resembling a cauliflower or a solid blister by producing excess cells. Mucocutaneous lesions: Hands, feet, genital area and even other locations. A small, rough benign tumor

6 Common wart: HPV-2, -3 and -10 (on knees and fingers)






12 plantar wart: HPV-1 HPV-4




16 Genital warts HPV-6, -11, -16, -18 and- 32
on penis, vulva and perianal regions. Can blossom into cauliflower-like protuberances. Transmission through sex contacts is increasing.



19 HPV & Cervical Cancer 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.

20 HPV Pathogenesis (1) It infects cells in the basal layers of the skin or mucosa. Common period: 1-6 months Viral antigen and infectious virus is produced when the cells begin to become squamifed and keratinized. Several months later, the wart may regress.

21 HPV Pathogenesis (2) Cell mediated immunity (CMI) responses are more important in recovery. In immunocompromised patients (e.g. post transplant), there may be warts as a result of reactivation.

22 Diagnosis Diagnosis is clinical
HPV cannot be cultivated in the laboratory Serological tests are neither useful nor available

23 Treatment Removing warts by surgery. 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)

24 Structure: Polyoma viruses
DNA virus, double strand, circular, Icosahedral nucleocapsid, small size (45-55nm). No envelope Well-known Human polyoma viruses: JC and BK (all around the world)

25 JC and BK viruses They can be remained in kidney & lymphoid tissues after a primary infection. They can be reactivated after kidney transplantation or pregnancy or oldness.

26 Clinical findings Polyomavirus (BK) nephropathy usually happens in 5% of kidny recipients and causing rejection in 50% of them. BK hemeoragic cystitis in patients with bone morrow transplantation. JC is the agent of PML (progressive multiphocal locoencephalopaty) in immune deficiency involving 5% of AIDS cases.


28 Parvoviruses Structure:
- Nonenveloped, icosahedral particle, Single and Positive DNA strand. - Very small viruses (18-26 nm) and ubiquitous. - Infect many species of animals.



31 Parvoviruses - 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.

32 B19 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.

33 B19 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) % infections are asymptomatic.

34 Fifth disease (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.








42 Anemia & 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.

43 Diagnosis Detecting viral DNA in serum (PCR)
A rise in parvovirus-specific IgM or IgG. Bone marrow examination shows an absence of erythroid precursors.

44 Transmission B19 is anywhere, all through the year, different ages, sporadic or epidemic. Spread through respiratory secretions, vertical transmission from mother Many cases are subclinical.

45 Control 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

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