Chapter XI: Adenoviridae and Papillomaviridae PDF

NLML404 – Clinical Virology Dr. Ali El Roz 1  Structure Adenoviruses are naked viruses with linear double-stranded DNA having an icosahedral capsid Each penton carries a spike glycoprotein called fiber, with a sphere that has...

NLML404 – Clinical Virology Dr. Ali El Roz 1  Structure Adenoviruses are naked viruses with linear double-stranded DNA having an icosahedral capsid Each penton carries a spike glycoprotein called fiber, with a sphere that has an HA activity. Human adenoviruses are divided into 51 serotypes divided into 6 groups (A to F) based on their tissue tropism.  Physiopathology They multiply especially in the respiratory tract, eye and gastrointestinal tract Incubation period : 1-10 days Infections caused by adenoviruses are often asymptomatic in immunocompetent individuals  Physiopathology They are responsible for various infections: - Respiratory (pharyngitis, laryngitis, pulmonary disease,...) - Eye ("pools" conjunctivitis, acute hemorrhagic conjunctivitis, Keratoconjunctivitis...) - Digestive (Gasto-enteritis) Different routes of transmission - Direct contact - Airway - fecal-oral route  Diagnosis Direct diagnosis : - Isolation in cell culture: adenoviruses grow well in cell cultures but sometimes it takes time. - search of viral antigen by immunofluorescence - search the viral genome by PCR Indirect diagnosis : - The demonstration of seroconversion to confirm the diagnosis of current infection - Group serodiagnosis - Detection of the serotype can be made by haemagglutination inhibition or virus neutralization  Structure Papillomaviruses are naked viruses with circular double-stranded DNA having an icosahedral capsid Viral genome encodes 8 proteins : - 6 proteins involved in viral replication: E1, E2, E4, E5, E6 and E7 - 2 structural proteins (capsid components): L1 and L2 E6 and E7 are the main proteins involved in carcinogenesis  Physiopathology Papillomaviruses are the cause of benign tumors of the skin and mucous membranes in humans and various animal species "Human Papillomavirus" or "HPV" are those strictly human Following penetration, the virus multiplies in epithelial cells (skin or mucosal epithelium) Tumors induced by HPV are called "papillomas" and are classified into two main categories: - cutaneous warts (palmar, plantar,...) (benign tumors) - anogenital -Condylomes (benign)  Physiopathology In humans, more than 120 HPV genotypes have been described, including forty preferentially infect the anogenital Among the HPV genital tropism, there are - High-risk HPV oncogenic (cancer lesions) - Low-risk HPV (non-cancerous potential) HPVs have high tissue specificity  Physiopathology Contamination occurs : - by direct contact (in case of skin warts) - by sexual route (in case of anogenital warts) The asymptomatic HPV infections are very common HPV infections are a long incubation infections  Diagnosis The diagnosis is primarily clinical, cytology (cervical smear) or histological (biopsy). Direct diagnosis: viral genome research Indirect diagnosis is not usually done in practice  Vaccination Vaccines against HPV are recombinant vaccines: they consist of the protein of the L1 capsid. Two vaccines currently exist : - Gardasil : quadrivalent vaccine (HPV 6, 11, 16 et 18) - Cervarix: bivalent vaccine (HPV 16 et 18) Vaccination against HPV is recommended for girls and boys (11 - 12 years). The protocol consists of 3 injections spread over 6 months (0, 1 and 6 months).