Papilloma viruses & Polyoma viruses

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

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.

HPV

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

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

plantar wart HPV-1 HPV-4

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

HPV & 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) 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.

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.

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

Treatment Using keratolytic agents: Salicylic acid (to soften and cause desquamation of epithelium or horny layer of skin).causedesquamationepitheliumhornylayerskin Removing warts by surgery.warts Destruction of wart tissue by freezing with dry ice (solid CO2) or with liquid nitrogen. Using Podophyllin

Polyoma viruses

JC and BK viruses

Clinical findings

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.)DNA replicationchromosomes Virus replication is in nucleus of the cell.Parvoviruses

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). It can transmit from mother to embryo. B19 can be found in blood and respiratory secretions.

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.

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.

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. Anemia & aplastic crisis

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

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.

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