T-cell activation: a cellular target for antiretroviral therapy

Follow-up of antiretroviral treatment in liver transplant recipients with primary and chronic HIV type 1 infection

The prognosis of HIV-1-infected patients has dramatically improved but progression to liver failure occurs now frequently in subjects coinfected with hepatitis C virus (HCV). This has raised the issue of organ transplantation, but the knowledge about the effect of concomitant antiretroviral and immunosuppressive therapy is limited. The objective of the study was to describe viral and immunological events in antiretroviral-treated orthotopic liver transplant (OLT) recipients with primary (PHI) or chronic HIV-1 infection. Three HIV-1-infected patients with liver cirrhosis due to chronic HCV infection underwent OLT. A fourth patient developed PHI at OLT. Immunosuppressive drugs and combination antiretroviral therapy were given. The effects on HIV-1 load, viral diversity and divergence, and CD4(+) T cell counts, were studied. One patient died after 3 months. Three subjects were alive after 9 months, 14 months, and 3 years, respectively. In the PHI patient, viral load decreased during the second week of illness despite immunosuppression. During the third week the viremia increased until antiretroviral treatment was initiated. In all four patients, the HIV-1 replication was effectively inhibited during follow-up by the treatment, as determined by undetectable plasma viremia, lack of viral sequence changes, and increase in CD4(+) T cells. The pattern of viral dynamics may suggest that the innate immunity causes the earliest decline of viral load in PHI patients. A lack of adaptive immunity may thereafter lead to an increase in viremia in heavily immunosuppressed individuals. However, a specific HIV-1 immunity is not necessary to efficiently inhibit the viral replication when potent antiretroviral therapy is given in liver transplant recipients with primary or chronic HIV-1 infection.

Effect of target cell availability on HIV-1 production in vitro

OBJECTIVE

The recovery of CD4 target cells following antiretroviral therapy may facilitate virus production and escape from antiretroviral suppression. To address this hypothesis, we directly examined whether the CD4 target cell number increases viral production in the presence of suboptimal therapy.

DESIGN

The effect of the CD4 T cell number on HIV-1 replication with a suboptimal dose of zidovudine was studied in vitro.

METHODS

Varying numbers of CD4 T cells were infected with HIV-1 and treated with 1 nM zidovudine. Virus production was measured by p24 antigen capture enzyme-linked immunosorbent assay. Partial sequencing of HIV-1 pol was performed to assess zidovudine-resistant mutations.

RESULTS

Wild type virus production was found to increase eightfold in cultures with 100 x 10(4) cells compared with cultures with 10 x 10(4) cells. The IC90 of zidovudine was 4 logs higher in cultures with 16 x 10(4) cells compared with cultures with 1 x 10(4) cells. No zidovudine-resistant mutations were found.

CONCLUSION

Target cell availability may play a direct role in wild type HIV-1 resurgence following therapy.