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The below mentioned article provides a short note on Miscellaneous Viruses.
Papova Viruses:
Papova (from pa, papilloma, po, polyoma, va, vacuolaling agent) Viridae family comprises of papilloma virus of man and rabbits, polyoma virus of mice and simian virus 40 (SV 40)— the vacuolating agent (virus) of rhesus monkeys.
Virology:
These viruses are small 42-55 nm diam., icosahedral, enveloped, contain double stranded circular DNA and replicate in cell nucleus. They can produce tumours.
Human Papilloma Virus:
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It causes infectious warts in hand, face, feet, larynx or genitalia. These warts are transmitted by direct or indirect contact (sexual). Incubation period is 2-8 months. The virus multiplies in the connective tissue of dermis followed by proliferation and hyperkeratinisation of the epidermis.
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Regression of most lesions is spontaneous. As long as the virus multiplies in warts, antibody (Ig M) is present in serum of patient. More than 50 types of human papilloma virus (HOV) are known to produce lesions associated with human papilloma. Papilloma virus can remain latent in normal epithelium. Viral DNA may be detected in about 80% cytologically normal cervices of women.
Pathogenesis:
1. Cutaneous Warts:
They are common in children and disappear spontaneously within 2 years of onset. Recurrence is due to persistence of the virus in the skin surrounding the original wart.
2. Genital Warts:
It are commonest in sexually active women. Lesions are on vulva, within vagina, and on cervix. In men, the lesions are on shaft of penis, perianal skin, and anal canal. Subclinical infection may be present in both men and women.
3. Recurrent Respiratory Papillomatosis:
Benign squamous papilloma appears on larynx. Children below 5 years of age may acquire the lesions during passage through an infected birth canal. Adults are infected by orogenital contact.
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4. Oral Papillomatosis:
It occurs during oral genital contact with infected sexual partner. Buccal mucosa with multiple papillomatous lesions are called “Oral florid papillomatosis” which may progress to malignancy in which HPV DNA has been demonstrated.
Relation of HPV with Cancer:
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Cervical intraepithelial neoplasia (CIN) precedes cervical cancer and progresses from grade 1 to grade 3. HPV DNA has been detected in all grades of premalignant lesions of the female and male genital tract (HPV types 6,11). HPV types 16,18 and 31 have been detected in 60-100% of cervical cancers. Papilloma virus (Shope papilloma) causes a benign wart in rabbit which often progresses to cancer after several months.
