Background:  Among persons with hepatitis C virus (HCV), HIV co-infection results in increased HCV RNA levels, more rapid progression to cirrhosis and end-stage liver disease and reduced HCV treatment response rates. Given their principle sites of replication, the opportunity for direct viral interactions between HIV and HCV would appear to be limited. Nonetheless, several lines of evidence suggest that multiple liver cell types can be productively infected with HIV in vitro. We therefore investigated the detection of HIV RNA in liver biopsy tissues from persons with HIV/HCV co-infection.

Methods:  Liver tissues were obtained by core needle biopsy from 8 individuals with HIV/HCV co-infection. For 3 of these persons, half of the biopsy tissue was used for in vitro expansion of intrahepatic lymphocytes in the presence of anti-CD3 and interleukin (IL) -2 for approximately 3 weeks. Viral RNA was extracted from all biopsy tissues, as well as from expanded liver tissues, cell culture supernatants, intrahepatic lymphocytes, and the corresponding plasma when available. The presence of HIV RNA was detected by nested real-time polymerase chain reaction (RT-PCR) for a 485-nucleotide fragment of gag (p24) or a 337-nucleotide fragment of envelope (env). PCR products were then cloned and at least 10 clones per tissue or cell type were sequenced. Phylogenetic analysis was performed to examine clustering of viral sequences in different compartments.

Results:  HIV RNA was detected in fresh liver biopsy tissue from 4 of 8 (50%) individuals. HIV RNA was also detected after in vitro expansion in 2 of 3 biopsies. HIV RNA was also detected in intrahepatic lymphocytes (1 person) and the corresponding cell culture supernatant (2 persons) after in vitro expansion. For 2 individuals with available sequence data, the consensus p24 nucleotide sequences were distinct for each tissue or cell compartment analyzed. Intrapatient genetic distances were also higher for serum and liver biopsy samples compared to cell culture supernatants.

Conclusions:  Our data suggest that HIV RNA can be detected in liver biopsies from persons with HIV/HCV co-infection. The detection of HIV RNA in intrahepatic lymphocytes (and cell culture supernatants) after in vitro expansion suggests that this cell type may serve as a reservoir for HIV replication in the liver. Further investigation is underway to determine the clinical variables associated with HIV detection in the liver and its pathogenic consequences on hepatic function and HCV replication.