Nancy Odaka

RISK FACTORS FOR SEROCONVERSION TO HUMAN IMMUNODEFICIENCY VIRUS AMONG MALE HOMOSEXUALS: Results from the Multicenter AIDS Cohort Study

2507 homosexual men who were seronegative for human immunodeficiency virus (HIV) at enrollment were followed for six months to elucidate risk factors for seroconversion to HIV. 95 (3.8%) seroconverted. Of men who did not engage in receptive anal intercourse within six months before baseline and in the six-month follow-up period, only 0.5% (3/646) seroconverted to HIV. By contrast, of men who engaged in receptive anal intercourse with two or more partners during each of these successive six-month intervals, 10.6% (58/548) seroconverted. No HIV seroconversions occurred in 220 homosexual men who did not practise receptive or insertive anal intercourse within twelve months before the follow-up visit. On multivariate analysis receptive anal intercourse was the only significant risk factor for seroconversion to HIV, the risk ratio increasing from 3-fold for one partner to 18-fold for five or more partners. Furthermore, data for the two successive six-month periods show that men who reduced or stopped the practice of receptive anal intercourse significantly lowered their risk of seroconversion to 3.2% and 1.8%, respectively. Receptive anal intercourse accounted for nearly all new HIV infections among the homosexual men enrolled in this study, and the hazards of this practice need to be emphasised in community educational projects.

Flow cytometric analysis of γδ T cells and natural killer cells on HIV-1 infection

Abstract We have previously shown that HIV-1 seropositivity is associated with an increase in the difference between the number of CD3 + lymphocytes and the total number of CD4 + and CD8 + lymphocytes [CD3 − (CD4 + CD8)] among peripheral blood lymphocytes (PBL). To investigate the cellular basis of this increase, PBL from seronegative (SN) and AIDS-free seropositive (SP) homosexual men and intravenous drug users were analyzed by two-color flow cytometry. Results showed that SP compared to SN manifested the expected elevation in calculated [CD3 − (CD4 + CD8)] cells (87 vs 28 cells/mm 3 ; P + CD4 − CD8 − phenotype (67 vs 56 cells/mm 3 ; P >0.10) or the CD8 dim phenotype (135 vs 142 cells/mm 3 ; P >0.10). However, SP had significantly lower numbers of cells expressing the CD56 + CD3 − phenotype characteristic of natural killer cells (81 vs 170 cells/mm 3 ; P 3 ; P = 0.010). The latter difference was primarily due to higher numbers of cells coexpressing γδ-TCR and low levels of CD8 (27 vs 15 cells/mm 3 ; P = 0.009). These data suggest that HIV-1 seropositivity is associated with low numbers of natural killer cells and high numbers of CD8 + γδ-TCR lymphocytes. Changes in these populations may reflect altered host defense against HIV-1 or altered T cell kinetics in the presence of HIV-1 infection.

A comparison of risk factors for human immunodeficiency virus and hepatitis B virus infections in homosexual men

We analyzed cross-sectional data from 1062 homosexual men recruited in Baltimore during 1984, to directly compare risk factors for human immunodeficiency virus (HIV) and hepatitis B virus (HBV). Using polychotomous logistic regression, risk factor odds ratios (ORs) and 95% confidence intervals were determined for men with HIV alone, men with HBV alone, and men with both HIV and HBV, compared to seronegative men, and paired comparisons among these subgroups. Factors associated with the serologic prevalence of HIV alone and HBV alone (with respective ORs) included and receptive intercourse (HIV OR = 1.23; HBV OR = 1.12), history of gonorrhea (HIV OR = 4.58; HBV OR = 2.52), and rectal douching (HIV OR = 1.41; HBV OR = 1.20). Additional factors associated with HBV alone were years of homosexual activity (OR = 1.65), sexual activity with a person who developed acquired immunodeficiency syndrome (AIDS) (OR = 1.98), and lifetime number of male sex partners (OR = 1.25). HIV and HBV coprevalence was associated with anal receptive intercourse (OR = 1.36), history of gonorrhea (OR = 2.94), rectal douching (OR = 1.45), sexual activity with a person who developed AIDS (OR = 3.87), lifetime number of male sex partners (OR = 1.21), and the lifetime sum of sexually transmitted diseases (OR = 1.47). These findings reinforce the need for following safer-sex guidelines to prevent both infections and in the case of HBV, the prevention strategies should include vaccination.

Longitudinal study of homosexual couples discordant for HIV-1 antibodies in the Baltimore MACS Study.

Thirty-six sexually active couples serologically discordant for human immunodeficiency virus, type 1 (HIV-1), within the Baltimore Multicenter AIDS Cohort Study (MACS) were assessed to determine whether evidence of HIV-1 infection could be detected in the HIV-1-antibody-negative partners and whether factors associated with lack of transmission of HIV from the seropositive to the seronegative partner could be ascertained. Six HIV-1 seropositive couples and 18 seronegative couples were followed concurrently for comparison. None of the seropositive subjects had an AIDS-defining illness at entry into the study, and all subjects were followed for 1 year. A separate evaluation of unprotected anal receptive and insertive intercourse between discordant couples indicated high-risk activities for a median of 40 months, as reported by the HIV seropositive partner. Despite this finding, none of the HIV-1 seronegative men in discordant couples had evidence of HIV-1 infection by viral culture, p24 antigen testing, or polymerase chain reaction for HIV-1 DNA. Discordant seronegatives and seropositives did not differ from concordant seronegatives and seropositives in numbers of circulating CD4, CD8, and natural killer lymphocytes or in prevalence of antibodies to herpes simplex virus, type 1, Epstein-Barr virus, or cytomegalovirus, except that discordant seronegative men were less likely than their seropositive partners to have antibodies to herpes simplex virus, type 2. The reason for the apparent lack of HIV-1 infection in seronegative discordant individuals remains unexplained and did not appear to be associated with type of sexual activity, T-lymphocyte subsets or natural killer cells, or early stage of HIV-1 disease.