Human immunodeficiency virus type 1 (HIV-1) group N from Cameroon is phylogenetically close, in env, to the simian immunodeficiency virus (SIV) cpz-gab from Gabon and SIVcpz-US of unknown geographic origin. We screened 29 wild-born Cameroonian chimpanzees and found that three (Cam3, Cam4, and Cam5) were positive for HIV-1 by Western blotting. Mitochondrial DNA sequence analysis demonstrated that Cam3 and Cam5 belonged to Pan troglodytes troglodytes and that Cam4 belonged to P. t. vellerosus. Genetic analyses of the viruses together with serological data demonstrated that at least one of the two P. t. troglodytes chimpanzees (Cam5) was infected in the wild, and revealed a horizontal transmission between Cam3 and Cam4. These data confirm that P. t. troglodytes is a natural host for HIV-1-related viruses. Furthermore, they show that SIVcpz can be transmitted in captivity, from one chimpanzee subspecies to another. All three SIVcpz-cam viruses clustered with HIV-1 N in env. The full Cam3 SIVcpz genome sequence showed a very close phylogenetic relationship with SIVcpz-US, a virus identified in a P. t. troglodytes chimpanzee captured nearly 40 years earlier. Like SIVcpz-US, SIVcpz-cam3 was closely related to HIV-1 N in env, but not in pol, supporting the hypothesis that HIV-1 N results from a recombination event. SIVcpz from chimpanzees born in the wild in Cameroon are thus strongly related in env to HIV-1 N from Cameroon, demonstrating the geographic coincidence of these human and simian viruses and providing a further strong argument in favor of the origin of HIV-1 being in chimpanzees.
The objective of the study was to determine retrospectively which substitutions in the reverse transcriptase (RT) gene are selected in vivo during nucleoside RT inhibitors (NRTI) containing regimen in HIV-2 infected subjects. Thirty-four HIV-2 patients having received NRTI-containing regimen with available specimens and amplifiable RT gene were studied. Analyses of RT gene were undertaken after a median NRTI exposure of 51 months (range: 5-128). Mutations at positions known to be involved in HIV-1 resistance were observed in 26/34 patients. Selection of Q151M mutation was observed in nine out of 34 isolates (26%) after a median NRTIs exposure of 41 months (range: 12-77). In 8/9 cases, Q151M mutation was associated with other substitutions at positions known to be involved in HIV-1 resistance: K65R (n = 6), D67N (n = 1), N69S or T (n = 2), K70R (n = 3), M184V (n = 4), S215Y (n = 1). Compared with HIV-1 infection, there is a high frequency of selection of Q151M mutation in HIV-2 infected patients receiving various combinations of NRTIs. In these highly thymidine analogue pretreated patients, the selection of thymidine analogue mutations was low suggesting that the pathway to resistance is very different between these two viruses.
Objectives
Heavily treatment‐experienced patients with good virological control could be at risk of virological failure on switching to a new regimen if pre‐existing drug resistance is not taken into account. We examined whether genotyping based on cellular HIV‐1 DNA during controlled viraemia identifies resistance mutations detected in plasma HIV‐1 RNA during treatment with previous antiretroviral regimens.
Patients and methods
All 169 patients enrolled in the Agence Nationale de Recherche sur le SIDA (ANRS) 138‐intEgrase inhibitor MK_0518 to Avoid Subcutaneous Injections of EnfuviRtide (EASIER) trial had already received three antiretroviral drug classes [nucleoside reverse transcriptase inhibitor (NRTI), nonnucleoside reverse transcriptase inhibitor (NNRTI) and protease inhibitor (PI)] and had plasma HIV‐1 RNA < 400 copies/ml at baseline. The results of previous resistance genotyping of plasma HIV‐1 RNA in individual patients were compared with those of resistance genotyping of whole‐blood HIV‐1 DNA at randomization.
Results
A median of 4 plasma RNA genotypes were available for the 169 patients. The median numbers of resistance mutations in HIV‐1 RNA and DNA were, respectively, 5 and 4 for NRTIs, 2 and 1 for NNRTIs, and 10 and 8 for PIs. The difference was significant for all three drug classes (P = 0.001). Resistance to at least one antiretroviral drug was detected exclusively in HIV‐1 RNA or in DNA in 63% and 13% of patients for NRTI, 47% and 1% of patients for NNRTI, and 50% and 7% of patients for PI, respectively.
Conclusion
This study shows that, among highly treatment‐experienced patients on effective highly active antiretroviral therapy, resistance genotyping of HIV‐1 DNA detects fewer resistance mutations than previous analyses of HIV‐1 RNA. These results have implications for patient management and for the design of switch studies.
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