HIV type 1 infection among Ethiopian immigrants to Israel: enhanced in vitro antibody stimulation for estimating the length of the window period.

The window period between infection and seroconversion varies based on viral genetics, dose and route of transmission, host genetics, and environmental factors. The in vitro Stimmunology blood pretreatment assay was utilized to promote the synthesis of HIV-specific antibodies in efforts to define the window period between infection and seroconversion. Ethiopians seeking immigration to Israel while in refugee camps provided a unique cohort to perform a comparative analysis of the window period between HIV-1 infection and diagnosis utilizing conventional Ab-ELISA and our laboratory established an in vitro Stimmunolog assay. This population was considered unique due to its exposure to an environment with a high seroprevalence rate for a defined period of time. Unlinked blood samples were tested and validated before and after Stimmunology. Diagnostic screening was conducted in Israel. A total of 285 and 537 random samples were tested from the 1992 and 1998 immigrant population, respectively. Analysis of HIV prevalence, incidence, and window period length among the immigrants was measured by comparing results obtained on samples prior to and following analysis by Stimmunology as compared with standard ELISA-based assay. This novel assay that promotes the in vitro stimulation of antibody synthesis led to the diagnosis of 2.7% and 0.36% of the 1992 and 1998 immigrant groups, respectively, as HIV infected individuals during the window period. Using mathematical modeling, the length of the window period in the surveyed population was estimated to range from 2 to 5 months. Stimmunology-aided detection of early seronegative HIV-infected individuals provided a reliable and consistent mode of identifying infection in seronegative HIV-1-infected individuals. Applying mathematical modeling to the data obtained enabled us to define the window period length, which was found to extend beyond previous estimates. These results suggest a need for the reevaluation of the techniques that are employed to assess the true incidence and prevalence of HIV-1 infection, especially in populations within sub-Saharan Africa.