Host-dependent serum specificity to the V3 domain of HIV-1

Dendritic cells preferentially transfer CXCR4-using human immunodeficiency virus type 1 variants to CD4+ T lymphocytes in trans

Human immunodeficiency virus type 1 (HIV-1) preferentially utilizes the CCR5 coreceptor for target cell entry in the acute phase of infection, while later in disease progression the virus switches to the CXCR4 coreceptor in approximately 50% of patients. In response to HIV-1 the adaptive immune response is triggered, and antibody (Ab) production is elicited to block HIV-1 entry. We recently determined that dendritic cells (DCs) can efficiently capture Ab-neutralized HIV-1, restore infectivity, and transmit infectious virus to target cells. Here, we tested the effect of Abs on trans transmission of CCR5 or CXCR4 HIV-1 variants. We observed that transmission of HIV-1 by immature as well as mature DCs was significantly higher for CXCR4- than CCR5-tropic viral strains. Additionally, neutralizing Abs directed against either the gp41 or gp120 region of the envelope such as 2F5, 4E10, and V3-directed Abs inhibited transmission of CCR5-tropic HIV-1, whereas Ab-treated CXCR4-tropic virus demonstrated unaltered or increased transmission. To further study the effects of coreceptor usage we tested molecularly cloned HIV-1 variants with modifications in the envelope that were based on longitudinal gp120 V1 and V3 variable loop sequences from a patient progressing to AIDS. We observed that DCs preferentially facilitated infection of CD4(+) T lymphocytes of viral strains with an envelope phenotype found late in disease. Taken together, our results illustrate that DCs transmit CXCR4-tropic HIV-1 much more efficiently than CCR5 strains; we hypothesize that this discrimination could contribute to the in vivo coreceptor switch after seroconversion and could be responsible for the increase in viral load.

The rate of epidemiological and virological changes during the transition from nascent to concentrated HIV epidemic stage in the former Soviet Union countries

The rate of processes accompanying the transition of the HIV-1 epidemic from nascent stage to concentrated one in the Former Soviet Union (FSU) during intravenous drug user (IDU)-associated HIV infection outbreaks in 1994-1999 has not been analyzed. To define the rates, we studied susceptible populations and circulating viruses before, during, and after the outbreaks. Our findings included the following: (1) the pattern of high HIV-1 genetic diversity characteristic of the nascent epidemic changed to a concentrated one within 1 year in St. Petersburg and in Moscow; (2) different FSU regions were at different stages of the HIV-1 epidemic in 1994-1996; (3) the change of serotypic patterns characteristic of different stages of the HIV/AIDS epidemic for the non-IDU risk group occurred within 1 year in Moscow, suggesting an extremely high rate of IDU-associated epidemic pattern distributions in regions and susceptible populations in the FSU.