MORPHOLOGY: The virion is non-enveloped and has a diameter of 55 nm, icosahedral symmetry and 72 capsomers. The viral genome is a double stranded, circular DNA molecule with molecular weight of 5.2 million daltons. The viral capsid proteins consist of a major polypeptide and a number of minor polypeptides. Purified virion contains four histones of host origin.
PATHOGENESIS: Human papillomaviruses infect only epithelium of skin and mucous membranes. The virus probably infects cells of the lower layers of the epithelium which undergo proliferation and form the warts. Histologically, a wart is localised epithelial hyperplasia with a defined boundary and an intact basement membrane. Clinically warts can be of various types.
DIAGNOSIS: It is essentially clinical. History can confirm the diagnosis of warts but it does not indicate the type of HPV responsible. No serological tests are available for virus identification. Human papillomaviruses cannot be grown in culture. A broadly cross-reactive genus-specific antiserum is available, which is capable of recognising capsid antigen of all human and animal papillomaviruses by immunoperoxidase or immunofluorescent tests. Identification of viral genotype is possible by DNA hybridisation methods.
TREATMENT: Most skin and genital warts regress spontaneously. The patient seeks treatment for cosmetic reasons, pain, discomfort, and disability depending on the location and size of warts. The treatment includes application of caustic agents such as podophyllin and salicylic acid, cryotherapy, surgical removal, and antimetabolites such as 5-fluorouracil.
RELATED;
2. INFECTION BY THE MUMPS VIRUS
4. RETROVIRUSES
No comments:
Post a Comment