Presentation on theme: "Papilloma viruses & Polyoma viruses. Human Papilloma viruses (HPV) DNA virus, double strand, circular, Icosahedral nucleocapsid, small size (45-55nm)."— Presentation transcript:
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 Some cause warts and some others are associated with cancer. They are transmitted by contacts (both direct and indirect ).
Wart Wart (Condylomata accuminata by HPV-2, -3, -10) cauliflower excess cells Resembling a cauliflower or a solid blister by producing excess cells.blister Mucocutaneous lesions Mucocutaneous lesions: Hands, feet, genital area and even other locations. benign A small, rough benign tumortumor
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) cells in the basal layers It infects cells in the basal layers of the skin or mucosa. 1-6 months Common period: 1-6 months squamifedkeratinized Viral antigen and infectious virus is produced when the cells begin to become squamifed and keratinized. the wart regress Several months later, the wart may regress.
HPV Pathogenesis (2) Cell mediated immunity Cell mediated immunity (CMI) responses are more important in recovery. immunocompromised In immunocompromised patients (e.g. post transplant), there may be warts as a result of reactivation.
Diagnosis clinical Diagnosis is clinical cannot be cultivated HPV cannot be cultivated in the laboratory Serologicalneither useful nor available 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).cause desquamationepitheliumhornylayer skin Removing warts by surgery.warts 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)American Mayapple
Polyoma viruses Structure: 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)
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.
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.
Parvoviruses Structure: - Nonenveloped, icosahedral particle, Single and Positive DNA strand. - Very small viruses (18-26 nm) and ubiquitous.- Infect many species of animals.
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.
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.
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.
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.
Anemia aplastic crisis 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.
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