Human papillomavirus infection among HIV-infected individuals. Implications for development of malignant tumors

Human papillomavirus (HPV) infection has been strongly associated with development of anogenital squamous cell cancer. Cell-mediated immunity likely plays an important role in prevention of HPV-associated disease, and HPV-associated squamous cell cancer has been shown to occur with increased frequency among iatrogenically immunosuppressed individuals. Similarly, individuals with HIV-associated immunodeficiency have been shown to have a high prevalence of anogenital HPV infection as well as a high prevalence of HPV-associated lesions that are thought to be cancer precursors. Thus, HIV-positive women have a high prevalence of cervical intraepithelial neoplasia, and HIV-positive men have a high prevalence of anal intraepithelial neoplasia. The risk of disease in these populations appears to increase as the degree of immunosuppression increases, and these individuals are likely at risk for development of invasive squamous cell cancer. Because these diseases are preventable, women should be screened on a regular basis with cervical Pap smears, followed by colposcopy if the Pap smear is abnormal. Although preliminary studies indicate that anal Pap smears may also be useful for screening, further trials need to be performed, and at this time, HIV-positive men should be assessed on a regular basis with anoscopy. Lesions that are detected should be biopsied for histopathologic assessment. Thorough assessment of the entire anogenital region should be performed because of the multicentric nature of HPV-associated diseases. Following treatment, rigorous follow-up should be maintained because of the high recurrence rate of HPV-associated disease in these populations.

Human papillomavirus infection in sexually active adolescent females: prevalence and risk factors

We examined the prevalence of human papillomavirus (HPV) infection, and associated risk factors for infection with HPV types 6, 11, 16, 18, 31, 33, and 35, in 661 sexually active adolescent females attending family planning clinics. Fifteen percent were positive for HPV DNA by RNA-DNA dot-blot hybridization. More than 60% of the HPV-positive subjects harbored at least one of the following cancer-related HPV types: 16, 18, 31, 33, or 35. Those with HPV had a mean range of four to 10 lifetime sexual partners compared with a mean range of one to three in those without HPV (p less than 0.001). After the analysis was adjusted for number of lifetime sexual partners, no other risk factor was associated with HPV infection. We conclude that oncogenic-related HPV types are common sexually transmitted organisms found in our population. The strong relationship with number of sexual partners suggests that acquisition of HPV infection is predominantly influenced by sexual behavior. However, in our population, confounders such as oral contraceptive use, past history of Chlamydia trachomatis infection, or substance abuse were not found to be significant independent risk factors.

Interaction of human immunodeficiency and papilloma viruses: association with anal epithelial abnormality in homosexual men

During the 7th annual follow-up of our cohort of homosexual men in 1989, we tested the hypotheses that infection with human immunodeficiency virus (HIV) may enhance the expression of human papilloma virus (HPV) and that the development of anal epithelial abnormality is related to a biologic interaction between these two viruses. Overall, 41 (39%) of the 105 men had anal swabs positive for one or more genotypes of HPV 6/11, 16/18 or 31/33/35. Twenty-three (53%) of the 43 HIV-positive subjects harbored HPV compared to 18 (29%) of the 64 HIV-negative subjects (p = 0.012), including higher prevalence rates for HPV genotypes 16/18 (p = 0.01), 6/11 (p = 0.007), and 31/33/35 (p = 0.07). Multivariate logistic regression analysis of the HIV-positive subjects showed low CD4+ cell counts to be an independent risk factor for detection of HPV (p = 0.04) and in particular for HPV genotypes 31/33/35 (p = 0.02) and 6/11 (p = 0.07). In contrast, similar analysis of the HIV-negative subset showed that a positive antibody test for syphilis was associated with HPV (p = 0.03). Anal epithelial abnormalities were found in 13 (14%) of 92 technically adequate cytologic smears and were strongly associated with detection of any HPV genotypes by the dot-blot method (p = 0.01), and in particular with HPV genotypes 6/11 (p = 0.001). None of 15 subjects with HPV detected only by PCR had anal epithelial abnormality. We propose a viral interaction model, in which HIV-related immune deficiency allows reactivation of HPV, with a subsequent or concomitant appearance of epithelial abnormality.

Immune status as a determinant of human papillomavirus detection and its association with anal epithelial abnormalities

One hundred and twenty Danish homosexual men were enrolled to characterize risk factors for anal type-specific human papillomavirus (HPV) expression and to examine its association with anal epithelial atypia. Detection of HPV strongly correlated with immunosuppression measured by T-lymphocyte subset markers and rose nearly linearly from 7.3% among subjects with CD4/CD8 ratios above 1.0 to 35.3% among those with a ratio below 0.4 (p trend = 0.003). No association was found between presence of HPV and a wide range of lifestyle factors including number of sex partners/year, smoking, alcohol consumption and illegal drug intake. However, self-reported history of anal condyloma in the past year was correlated with HPV (p less than 0.001). Simultaneous testing for presence of HPV in the oral cavity showed evidence of HPV 16,18 and 31,33,35. Anal smears were abnormal in 19.5% of the men and correlated strongly with presence of HPV (OR = 6.1, p less than 0.001). Type-specific associations were found with HPV 31/33/35 (OR = 8.5) and HPV 16/18 (OR = 3.1) only. The association remained significant after adjusting for immune status. Overall, HPV was detected in 50% of the cases with abnormal smears. However, HPV was found in all subjects with abnormal smears and a CD4/CD8 ratio below 0.4, compared to only 3 of 14 subjects with abnormal smears and a ratio greater than or equal to 1.3. In conclusion, (1) HPV may be missed in a substantial number of infected subjects with a normal immune system. This may have an impact on studies trying to describe risk factors for HPV transmission and its correlation with cancer development. (2) The finding of HPV 16,18 and 31,33,35 in the oral cavity makes oral-genital sexual activity at least a hypothetical route of transmission for these HPV types. (3) HPV appears to play a central role in the development of anal epithelial abnormality.

Influenza B virus PB1 protein; nucleotide sequence of the genome RNA segment predicts a high degree of structural homology with the corresponding influenza A virus polymerase protein

The complete nucleotide sequence of a cloned cDNA copy of the genome RNA segment encoding the influenza B/Lee/40 virus PB1 polymerase protein has been determined. The genome RNA segment is 2368 nucleotides in length and is capable of encoding a polymerase (PB1) protein of 752 amino acids with a calculated mol mass of 84,407 Da. As expected, the protein is highly basic with a net charge of +20 at pH 7.0. Sequence comparison between the influenza A and B virus PB1 proteins reveals that they share 61% amino acid homology. An internal hydrophobic domain and 90% of the proline residues found within the influenza A virus PB1 protein are conserved in the influenza B virus molecule. The influenza A and B virus PB1 proteins share the highest homology yet seen between proteins encoded by these disparate viruses. This remarkable conservation of primary structure argues for severe functional constraint on the evolution of this influenza virus polymerase protein.