OBJECTIVETo establish a cohort of human immunodeficiency virus (HIV) discordant couples for follow-up studies and to collect data on frequency of HIV heterosexual transmission and related factors.

METHODSA total of 52 HIV discordant couples were identified by face to face interview and serological testing, in which the HIV negative individuals had no HIV infection behaviors including injecting drug use, blood transfusion or having sexual partners other than his/her own wife/husband. Three times of follows-up studies were carried out in 0.5 year, 1 year and 2.5 years to collect information on their sexual practices and condom use through face to face interview together with 20 ml whole blood collected to test HIV antibody, CD4+ T cell count and viral load.

RESULTS(1) In the period of 2.5 years follow-up, no HIV seroconversion and HIV transmission was found. (2) The frequencies of sexual intercourse between once per month to once per week were 65.4%, 72.9%, 71.7% and 80.0% at the time of cohort setup: 0.5 year, 1 year and 2.5 years of follow-up respectively. The rates of "occasional use" to "never use" condoms were 76.9%, 66.6%, 69.1% and 60.0% at the time of cohort setup as: 0.5 year, 1 year and 2.5 years of follow-up, respectively. No significant difference between different times of follow-up for sexual intercourse or condom use. (3) 85.4%, 66.6% and 60.0% of the HIV positive individuals kept their CD4+ T cell count stabilized or raised during the 0.5 year, 1 year and 2.5 years follow-up period, respectively. However, 66.7% of them showed stable or declined viral load in the period of 2.5 years follow-up. It appeared that stable or raised CD4+ T cell and the stable/declined viral load happened simultaneously.

CONCLUSIONNo transmission was identified in this study. The stabilized CD4+ T cell count and viral load might be account for the reason of no transmission while the biological factors from host and virus related with transmission need to be further studied.