Characterization of HIV-1 genotypes and antiretroviral drug-resistance mutations among patients in Burkina Faso.

The purposes of this study were: (1) to describe the genetic variability of HIV strains found in Burkina Faso, (2) to characterize non-B HIV strains mutation profiles selected by ARVs and (3) to detect possible resistances induced by ARV drugs. From 30 October 2002 to 20 November 2003, 132 HIV 1-positive patients taking Highly Active Antiretroviral Therapy (HAART) for more than one year in Bobo-Dioulasso and Ouagadougou were included. T-CD4+ lymphocytes count was done using Dynabeads technique while genotypic test and ARV-resistance tests were conducted using Pol sequencing that codes for reverse transcriptase reverse, integrase and protease. Due to undetectable viremia, 86 samples out of 132 could not be characterized. Whereas in the 46 others that had a viral load exceeding 1000 copies mL(-1), the following HIV-1 subtypes were identified: CRF06 (54,55%); CRF02(38,63%); CRF01 (4,55%) and subtype A (2,27%). In addition, several mutations related to PI, NRTI and NNRTI resistance were isolated in 27 samples. This study found a huge genetic HIV-1 polymorphism in Burkina Faso. The level of acquired resistance to ARV after one year of treatment amounted 20.4%. These results clearly show that there is imperative need to set up an ARV resistance surveillance network in Burkina Faso to guide treatment strategies and follow the extension of the phenomenon in the country.

Comparison of antibody responses after vaccination with two inactivated rabies vaccines.

Thirty laboratory dogs were randomly assigned to two groups (A and B) of 15 dogs and subcutaneously vaccinated with a single dose of one of two commercially available monovalent inactivated rabies vaccines: RABISIN (Merial, France) (group A) and NOBIVAC Rabies (Intervet International) (group B). Rabies antibodies were measured over a period of 4 months using the fluorescent antibody virus neutralization (FAVN) test. The two vaccines performed differently in terms of magnitude and persistence of rabies antibodies titers in dogs. Two weeks after vaccination, average rabies antibody titers peaked at 2.53 IU/mL (range, 0.17-13.77 IU/mL) and 1.26 IU/mL (range, 0.50-4.56 IU/mL) in groups A and B dogs, respectively. The average FAVN antibody titres against rabies on D28, D56, D84, D112 and D120 were significantly higher in group A than in group B. Although all dogs from group B serologically responded to vaccination, the proportion of dogs with antibody titres >or=0.5 IU/mL dropped significantly after D28 and was statistically significantly lower on D56, D84 and D112 compared to group A dogs. In conclusion, in the context of international trade, the choice of the vaccine and the timing of blood tests are critical factors in achieving successful serological test results after rabies vaccination. RABISIN induces high and sustained antibody titres against rabies, increasing the flexibility for the time of blood sampling after primo-vaccination.

Optimization of a genotypic assay applicable to all human immunodeficiency virus type 1 protease and reverse transcriptase subtypes.

Genotypic assays are used often to guide clinicians in decisions concerning the treatment of patients. An optimized sequence-based genotypic assay was used to determine the whole protease and reverse transcriptase (RT) gene, including the gag cleavage site region and RNase H region. Since non-B subtypes are increasing in countries where subtype B was the most prevalent subtype, and treatment becomes more available in developing countries where the epidemic is characterized by a high prevalence of non-B subtypes, it was important that the genotypic test was evaluated using a panel of different subtypes. Amplification was successful for different subtypes: A, B, C, D, F, G, H, J, CRF01_AE, CRF02_AG, CRF11_cpx, CRF13_cpx and an uncharacterized recombinant sample. The detection limit of the PCR was 1000 copies/ml, except for 1 subtype C sample (PL3) and 1 CRF02_AG sample (PL8). The detection limit for these samples was 5000 copies/ml. A sequence could be obtained in both directions for most of the samples.

Binding of human immunodeficiency virus type 1 gp120 to CXCR4 induces mitochondrial transmembrane depolarization and cytochrome c-mediated apoptosis independently of Fas signaling.

Apoptosis of CD4(+) T lymphocytes, induced by contact between human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (gp120) and its receptors, could contribute to the cell depletion observed in HIV-infected individuals. CXCR4 appears to play an important role in gp120-induced cell death, but the mechanisms involved in this apoptotic process remain poorly understood. To get insight into the signal transduction pathways connecting CXCR4 to apoptosis following gp120 binding, we used different cell lines expressing wild-type CXCR4 and a truncated form of CD4 that binds gp120 but lacks the ability to transduce signals. The present study demonstrates that (i) the interaction of cell-associated gp120 with CXCR4-expressing target cells triggers a rapid dissipation of the mitochondrial transmembrane potential resulting in the cytosolic release of cytochrome c from the mitochondria to cytosol, concurrent with activation of caspase-9 and -3; (ii) this apoptotic process is independent of Fas signaling; and (iii) cooperation with a CD4 signal is not required. In addition, following coculture with cells expressing gp120, a Fas-independent apoptosis involving mitochondria and caspase activation is also observed in primary umbilical cord blood CD4(+) T lymphocytes expressing high levels of CXCR4. Thus, this gp120-mediated apoptotic pathway may contribute to CD4(+) T-cell depletion in AIDS.

Patterns of resistance mutations to antiretroviral drugs in extensively treated HIV-1-infected patients with failure of highly active antiretroviral therapy.

Resistance-mutation patterns in the reverse transcriptase (RT) and protease genes of HIV-1 were analyzed in 22 patients who had been extensively pretreated and who failed to respond to highly active antiretroviral therapy (HAART). The number of mutations ranged from 8 to 19 (median, 13): 4 to 12 (median, 6) mutations in the RT gene, and 4 to 8 (median, 7) mutations in the protease gene. In the RT gene, the most frequent resistance mutations were found at codons 215 (100%), 41 (95%), 67 (91%), and 210 (77%). Multidrug-resistant mutation patterns including Q151M and insertion mutations at codon 69, which confer cross-resistance to the different nucleoside analogue RT inhibitors were detected in 1 and 3 patients, respectively; 1 patient with insertion mutation displayed a NGQGV [corrected] sequence at codons 67 to 70. In the protease gene, the most frequent mutations were found at codons 63 (95%), 10 (86%), 90(86%), 71(77%), 46 (50%), 36 (45%), and 84 (45%). Genotypic resistance to zidovudine, saquinavir, and indinavir was found in 100% of the patients. All patients showed also resistance or possible resistance to stavudine, abacavir, ritonavir, and nelfinavir. Mutations conferring genotypic resistance to nonnucleoside analogue RT inhibitors (NNRTIs) were found in 12 (80%) of the NNRTI-experienced patients and 1 of 7 NNRTI-naive patients. Our results indicate that failure of HAART in the patients extensively pretreated results from the multiplicity of RT and protease mutations that confer genotypic resistance to almost all available antiretroviral drugs. In these patients, genotypic resistance tests confirm the lack of alternative salvage therapy strategies based on the currently available antiretroviral drugs.

Genetic diversity of protease and reverse transcriptase sequences in non-subtype-B human immunodeficiency virus type 1 strains: evidence of many minor drug resistance mutations in treatment-naive patients.

Most human immunodeficiency virus (HIV) drug susceptibility studies have involved subtype B strains. Little information on the impact of viral diversity on natural susceptibility to antiretroviral drugs has been reported. However, the prevalence of non-subtype-B (non-B) HIV type 1 (HIV-1) strains continues to increase in industrialized countries, and antiretroviral treatments have recently become available in certain developing countries where non-B subtypes predominate. We sequenced the protease and reverse transcriptase (RT) genes of 142 HIV-1 isolates from antiretroviral-naive patients: 4 belonged to group O and 138 belonged to group M (9 subtype A, 13 subtype B, 2 subtype C, 5 subtype D, 2 subtype F1, 9 subtype F2, 4 subtype G, 5 subtype J, 2 subtype K, 3 subtype CRF01-AE, 67 subtype CRF02-AG, and 17 unclassified isolates). No major mutations associated with resistance to nucleoside reverse transcriptase inhibitors (NRTIs) or protease inhibitors were detected. Major mutations linked to resistance to non-NRTI agents were detected in all group O isolates (A98G and Y181C) and in one subtype J virus (V108I). In contrast, many accessory mutations were found, especially in the protease gene. Only 5.6% of the 142 strains, all belonging to subtype B or D, had no mutations in the protease gene. Sixty percent had one mutation, 22.5% had two mutations, 9.8% had three mutations, and 2.1% (all group O strains) had four mutations. In order of decreasing frequency, the following mutations were identified in the protease gene: M36I (86.6%), L10I/V (26%), L63P (12.6%), K20M/R (11.2%), V77I (5.6%), A71V (2.8%), L33F (0.7%), and M46I (0.7%). R211K, an accessory mutation associated with NRTI resistance, was also observed in 43.6% of the samples. Phenotypic and clinical studies are now required to determine whether multidrug-resistant viruses emerge more rapidly during antiretroviral therapy when minor resistance-conferring mutations are present before treatment initiation.

Most env and gag subtype A HIV-1 viruses circulating in West and West Central Africa are similar to the prototype AG recombinant virus IBNG.

The genetic subtype was identified in gag and env of 219 HIV-1-positive samples collected in different African countries, 44 from Senegal, 55 from Cameroon, 82 from Gabon, and 38 from Djibouti. In total, 20 (9.1%) samples had discordant subtypes between gag and env, 6 of 44 (13.9%) in Senegal, 4 of 55 (7.2%) in Cameroon, 1 of 38 (2.6%) in Djibouti, and 10 of 82 (12.1%) in Gabon. Subtypes A and G were predominantly involved in the recombination events. Phylogenetic tree analysis of gag showed that an important number of the A sequences form a distinct subcluster with the AG-IBNG prototype strain (a complex A/G mosaic virus): 27 of 32 (84.3%) in Senegal, 12 of 17 (70.6%) in Nigeria, 24 of 39 (61.5%) in Cameroon, and 38 of 70 (54.3%) in Gabon. Full-length genome analysis of 3 and additional sequences in pol for 10 such strains confirmed that they have a similar complex A/G mosaic genomic structure. These data suggest that in West Africa, most probably between 60% and 84% of the subtype A viruses are recombinant AG-IBNG viruses. This finding has potential implications on future vaccine, diagnostic, and treatment strategies. The actual and future role of these viruses in the global pandemic must be monitored in all new molecular epidemiologic studies, a discrimination between subtype A and AG-IBNG-like viruses is necessary.

Predominance of subtype A and G HIV type 1 in Nigeria, with geographical differences in their distribution.

The purpose of this study was to generate data on the relative prevalences of the HIV-1 subtypes circulating in Nigeria. A total of 252 HIV-1-positive samples collected during an epidemiologic survey conducted in April 1996 were genetically characterized by HMA (heteroduplex mobility assay) and/or sequencing. Samples were collected in Lagos, Calabar, Kano, and Maiduguri. Overall, the predominant env subtypes were A (61.3%) and G (37.5%). Subtype A is more prevalent in the south (p < 0.001), about 70% in Lagos and Calabar, whereas a quarter of the samples was classified as subtype G in these states. In contrast, subtype G is predominant in the north ( < 0.001), representing 58% of the samples in Kano. In the northeastern region, Maiduguri, almost similar proportions of subtype A and G were seen, 49 and 47.4%, respectively. A total of 37 samples was also sequenced in the p24 region from the gag gene; 13 (35%) had discordant subtype designations between env and gag. The majority of the gag (12 of 17) and env (14 of 22) subtype A sequences clustered with the A/G-IBNG strain. Within subtype G, three different subclusters were seen among the envelope sequences. These different subclusters are observed among samples obtained from asymptomatic individuals and AIDS patients from the four Nigerian states studied. In conclusion, we observed a limited number of HIV-1 subtypes circulating in Nigeria, with subtypes A and G being the major env subtypes responsible for the HIV-1 epidemic. Nevertheless, the high rate of recombinant viruses (A/G) and the different A/G recombinant structures indicate a complex pattern of HIV-1 viruses circulating in this country.

Characterization of a highly replicative intergroup M/O human immunodeficiency virus type 1 recombinant isolated from a Cameroonian patient.

A Cameroonian patient with antibodies reacting simultaneously to human immunodeficiency virus type 1 (HIV-1) group O- and group M-specific V3-loop peptides was identified. In order to confirm that this patient was coinfected with both viruses, PCRs with O- and M-specific discriminating primers corresponding to different regions of the genome were carried out with both primary lymphocyte DNA and the corresponding viral strains isolated from three consecutive patient samples. The PCR data suggested that this patient is coinfected with a group M virus and a recombinant M/O virus. Indeed, only type M gag sequences could be amplified, while for the env region, both type M and O sequences were amplified, from plasma or from DNA extracted from primary lymphocytes. Sequence analysis of a complete recombinant genome isolated from the second sample (97CA-MP645 virus isolate) revealed two intergroup breakpoints, one in the vpr gene and the second in the long terminal repeat region around the TATA box. Comparison of the type M sequences shared by the group M and the recombinant M/O viruses showed that these sequences were closely related, with only 3% genetic distance, suggesting that the M virus was one of the parental viruses. In this report we describe for the first time a recombination event in vivo between viruses belonging to two different groups, leading to a replicative virus. Recombination between strains with such distant lineages (65% overall homology) may contribute substantially to the emergence of new HIV-1 variants. We documented that this virus replicates well and became predominant in vitro. At this time, group O viruses represent a minority of the strains responsible for the HIV-1 pandemic. If such recombinant intergroup viruses gained better fitness, inducing changes in their biological properties compared to the parental group O virus, the prevalences of group O sequences could increase rapidly. This will have important implications for diagnosis of HIV-1 infections by serological and molecular tests, as well as for antiviral treatment.

A new apparatus for studying the effect of hydrostatic pressure on cells in culture : application to osteoblastic cells ROS 17/2.8.

Although mechanical stresses have long been recognized as an important factor in the regulation of bone remodeling, the mechanism underlying this effect has remained obscure. A number of methods have been devised to apply forces to bone tissues and bone-derived cells in order to investigate the biochemical results of mechanical stimuli. In this paper we report a method for applying a well controlled cyclic hydrostatic pressure on cultured ROS 17/2.8 osteoblastic lineage cells. This technique allows the investigation of the true frequency response of cells. Hydrostatic pressure with a 1 Hz frequency decreases alkaline phosphatase activity of confluent osteoblastic-like cells (ROS 17/2.8).

Influence of pretreatment clinical characteristics on the response rate to mitomycin/vindesine/cisplatin (MVP) in unresectable non-small cell lung cancer. ATTIT (Association pour le Traitement des Tumeurs Intra-Thoraciques).

The authors report their experience with the MVP (mitomycin/vindesine/cisplatin) regimen of the Memorial Sloan-Kettering Cancer Center (MSKCC) which showed the highest response rate in non-small cell lung cancer (NSCLC). The aim was to respect the original reported schedule to appreciate its activity, because the same drug combination with dose and schedule variations used by other investigators has failed to reproduce the original report results. 82 consecutive previously untreated patients with unresectable and/or metastatic NSCLC received mitomycin (8 mg/m2 days 1, 29, 71), vindesine (3 mg/m2, days 1, 8, 15, 22, 29, 43, 57, 71) and cisplatin (120 mg/m2, days 1, 29, 71), with evaluation on day 71. 24 objective responses were noted (29%) (2 complete response/22 partial response) (95% CI 19%-39%), without differences according to histology. Differences in median survival were noted according to the performance status and type of response. Overall survival rates in responding patients were similar to those noted with the original schedules. Analysis of selection criteria showed that there were more patients with bone (P less than 0.01) or liver metastases (P less than 0.05), less women (P less than 0.001) and less adenocarcinoma (P less than 0.001) than the MSKCC trial. A dose intensity analysis showed only a minimal difference in the average weekly doses of vindesine (10% lower than MSKCC trial: 1.8 mg/m2 vs. 2.25 mg/m2). Disease improvement, a subjective response criterion used in the MSKCC trial, was probably underestimated in the current study. We conclude that the potential benefit of chemotherapy with a three-drug combination in NSCLC is greatest in patients with stage IIIa and IIIb disease or stage IV disease with a good performance status and a low metastatic volume.