Quantitative differences in the distribution of zidovudine resistance mutations in multiple post-mortem tissues from AIDS patients

Increased mutations in Env and Pol suggest greater HIV-1 replication in sputum-derived viruses compared with blood-derived viruses

OBJECTIVE

Low-level HIV-1 replication may occur during antiretroviral therapy (ART) that suppresses plasma HIV-1 RNA to less than 50 copies/ml (suppressive ART). Antiretroviral drugs appear less effective in macrophages and monocytes compared with lymphocytes, both in vitro and as implied in vivo by greater viral evolution observed during suppressive ART. Our objective was to examine sputum, which is rich in macrophages, for evidence of increased HIV-1 replication compared with that in the blood during suppressive ART.

DESIGN

A cross-sectional study during suppressive ART was performed, and HIV-1 DNA sequences derived from induced sputa and peripheral blood mononuclear cells were compared.

METHODS

Multiple sequences encoding HIV-1 reverse transcriptase, protease, and envelope were generated using single-genome sequencing. Reverse transcriptase and protease sequences were analyzed for genotypic drug resistance. The evolutionary distances of env sequences from the inferred most recent common ancestor of infection were calculated, and CXCR4 usage was predicted.

RESULTS

Nine hundred seventy bidirectional sequences from 11 individuals were analyzed. HIV-1 env and pol derived from sputa had greater frequency of drug-resistance mutations (P = 0.05), evolutionary divergence (P = 0.004), and tendency for CXCR4 usage (P = 0.1) compared with viruses derived from peripheral blood mononuclear cells.

CONCLUSION

The greater frequency of HIV-1 drug-resistance mutations and divergence of HIV-1 env in sputa-derived viruses compared with peripheral blood mononuclear cell-derived viruses suggests greater HIV-1 replication in the respiratory tract compared with the blood. Characterization of viral evolution over time and by cell-type could identify cells that provide a sanctuary for low-level viral replication in the respiratory tract during suppressive ART.

Different resistance mutations can be detected simultaneously in the blood and the lung of HIV-1 infected individuals on antiretroviral therapy

In this retrospective study, matched peripheral blood and lung samples from patients on antiretroviral therapy were studied in order to investigate whether differences in mutations associated with resistance to nucleoside analogues could be detected between the lung and blood. Discordant mutation patterns in the reverse transcriptase (RT) between plasma and cell free bronchoalveolar lavage fluid (BAL-fluid) HIV-1 genomic RNA was observed in five out of seven patients on nucleoside reverse transcriptase inhibitor (NRTI) monotherapy and six out of seven on combination therapy. In the cellular compartments, DNA recovered from peripheral blood mononuclear cells (PBMCs) and cells from BAL-cells discordant HIV-1 resistance genotypes were detected in 15 out of 44 matched samples. Differences in resistant genotypes between PBMCs and BAL-cells were most pronounced in patients receiving combination antiretroviral therapy. The pattern and number of mutations in RT associated with resistance differed in the BAL-cells compared to PBMCs in four out of 12 subjects not receiving antiretroviral therapy at the time of bronchoscopy, three from 14 patients on NRTI monotherapy, five out of nine on dual combination therapy and three out of nine on HAART. The differences in the detection of resistance mutations between blood and the lung suggest that the lung is a site of replication for HIV-1.

In vivo HIV-1 compartmentalisation: drug resistance-associated mutation distribution

Four patients who had received highly active antiretroviral therapy (HAART), and had postmortem samples stored, were tested for genotypic resistance using consensus sequencing. One patient was further investigated using single-copy sequencing. Patients 1, 3, and 4 showed a relatively uniform distribution of resistance-associated mutations, with only a small number (one to three) of protease mutations detectable. Patient 2 had a number of detectable mutations (four to eight, depending on the tissue) with similar distributions between the tissues. The exception was viruses detected in the esophagus, which were more diverse. Plasma was a moderately representative tissue of the viruses circulating in these individuals. However, some mutations detectable in some tissues were not seen in plasma (e.g., M46I and D30N in the protease). Single-copy sequencing revealed a wide distribution of quasi-species and a number of defective viruses in the proviral DNA and RNA. This study supports the concept that a wide variety of quasi-species circulate in each individual and that there may be viruses evolving independently in different body compartments.

Histopathological detection of owl's eye inclusions is still specific for cytomegalovirus in the era of human herpesviruses 6 and 7

BACKGROUND

Cytomegalovirus (CMV) is the prototype member of the beta-herpesvirinae, which can cause multiple organ dysfunction in the immunocompromised host. Human herpesvirus 6 (HHV-6) and HHV-7 are newer members of the beta-herpesvirinae that can cause febrile illness in young children and are also possible pathogens in the immunocompromised patient.

AIM

CMV is detected in histopathological sections by visualisation of owl's eye inclusion bodies. The aim of this study was to quantify the relation between CMV, HHV-6, and HHV-7 viral loads and the presence of owl's eye inclusions in histological sections.

METHODS

Histopathological examination of postmortem material and recording of owl's eye inclusion bodies were performed. CMV, HHV-6, and HHV-7 were detected by qualitative and quantitative polymerase chain reaction (PCR) from the same postmortem samples. Statistical analysis of the histopathological and PCR results was performed.

RESULTS

There was a significant association between the detection of owl's eye inclusion bodies and positive CMV PCR (p < 0.001); the median CMV viral load was significantly higher in samples that were positive for owl's eye inclusions (p < 0.001). No association was found between the presence of owl's eye inclusions and HHV-6 or HHV-7 positivity.

CONCLUSION

Histological detection of owl's eye inclusion bodies is an insensitive but highly specific method for detecting CMV organ involvement. Owl's eye inclusion bodies are not associated with HHV-6 or HHV-7 infection.

The growth and the control of human immunodeficiency virus in the lung: implications for highly active antiretroviral therapy

In recent years, it has become apparent that the lung is an important niche for the proliferation of human immunodeficiency virus (HIV), which may have implications for highly active antiretroviral therapy (HAART). The lung itself is a major site for the opportunistic infections associated with the progression to acquired immune deficiency syndrome (AIDS), specifically Pneumocystis carinii, Myobacterium tuberculosis and pyogenic bacteria. These cases of active pulmonary complications are direct indicators of enhanced progression to AIDS-defining illness and increased morbidity and mortality. It is therefore essential that the interaction between the lung and HIV is fully understood. Recent research indicates the lung may be a major sanctuary for the virus, with distinct evolution and replication in contrast to other target organs for HIV. In this review, we will discuss the recent findings of HIV infection, evolution, host factors involved in the control of HIV within the lung and the impact this may have on current therapy.