Specific immune responses against hepatitis B virus (HBV) can be partially restored in patients coinfected with HIV and HBV by HAART, even if their HAART regimen doesn’t include drugs with a specific anti-HBV effect, according to a small study published in the December 15th edition of the Journal of Infectious Diseases, which is now available on-line.
Investigators in London studied five HIV/HBV coinfected patients for 24 weeks after either starting HAART or adding an antiretroviral drug which was also active against HBV to the regimen. The researchers wished to see whether HAART, with or without an anti-HBV drug, was capable of inducing HBV-specific immune responses. The research was prompted by studies showing that HIV-negative patients infected with HBV were able to recover some HBV-specific CD4 and CD8 immune response after treatment with lamivudine (also known as 3TC, a nucleoside analogue which is active against both HIV and HBV).
After 24 weeks of HAART, which did not include any drugs active against HBV, two patients saw a return of HBV-specific CD8 cell response. A third patient, who was initially taking dual nucleoside analogue therapy, experienced a return of HBV specific CD8 cell response after the addition of the nucleotide analogue adefovir (which, although effective against both HIV and HBV is only licensed for the treatment of HBV as the dose needed for HIV treatment causes toxicities). This individual also had a return of HBV specific CD4 cell response.
The recovery of immune responses to HBV was preceded by a reduction in HBV viral load and levels of HBV surface antigen. A fall in HBV viral load was accompanied by an improvement in ALT levels. CD4 cell count increased significantly in three patients in the study, but only one of these individuals experienced a restoration of HBV-specific immune response. Although HIV viral load fell significantly in three individuals, this was only accompanied by specific immune responses against HBV in one patient.
”Our preliminary findings from this longitudinal study of 5 patients need to be confirmed in larger studies”, caution the investigators, but “it appears that HAART alone may be insufficient for reconstitution of HBV-specific responses.” However, some reconstitution of specific responses can occur with a reduction in HBV viral load, even in if an individual has a high HIV viral load.
Further information on this website
Hepatitis B - overview
Hepatitis B - factsheet
Lascar RM et al. Reconstitution of hepatitis B virus (HBV)-specific T cell responses with treatment for human immunodeficiency virus/HBV coinfection. Journal of Infectious Diseases, 188 (on-line edition), 2003.