Chronic periadolescent cannabinoid treatment enhances adult hippocampal PSA-NCAM expression in male Wistar rats but only has marginal effects on anxiety, learning and memory

Pubertal and adolescent exposure to cannabinoids is associated with enduring alterations in anxiety and memory. However, periadolescence virtually remains unexplored. Here, we measured anxiety in the Elevated Plus Maze (EPM) in adult Wistar rats treated at periadolescence (P28-P38) with the cannabinoid agonist CP 55,940 (CP) (0.4 mg/kg; 2 ml/kg i.p., 1 daily injection), and we also defined their recognition memory in the novel object paradigm and spatial learning and memory in the water maze. Additionally, we measured the expression of hippocampal PSA-NCAM (Polysialic Acid-Neural Cell Adhesion Molecule) and long-term potentiation (LTP) as well as, given their role in mnemonic processing, the levels of plasma corticosterone and estradiol. We found that CP had no robust effects on anxiety or in recognition memory. In the water maze, only a slight decreased percentage of failed trials in the reference memory task and an improvement in an indirect index of attention were observed. However, we detected an up-regulation of hippocampal PSA-NCAM expression, only in CP-males, although this effect was not related to changes in LTP. No hormonal alterations were evident. Based on our data, minimal long-term effects on anxiety, learning and memory appear to result from cannabinoid exposure during the periadolescent period.

Antiretroviral drug resistance and phylogenetic diversity of HIV-1 in Chile

This study reports the analysis of human immunodeficiency virus type 1 (HIV-1) protease (PR) and reverse transcriptase (RT) coding sequences from 136 HIV-1-infected subjects from Chile, 66 (49%) of them under antiretroviral (ARV) treatment. The prevalence of mutations conferring high or intermediate resistance levels to ARVs was 77% among treated patients and 2.5% among drug-naïve subjects. The distribution of resistance prevalence in treated patients by drug class was 61% to nucleoside RT inhibitors, 84% to nonnucleoside RT inhibitors, and 46% to PR inhibitors. Phylogenetic analysis revealed that 115 (85%) subjects were infected with subtype B viruses, 1 with a subtype F1 virus, and 20 (15%) carried BF intersubtype recombinants. Most BF recombinants grouped into two clusters, one related to CRF12_BF, while the other could represent a new circulating recombinant form (CRF). In conclusion, this is the first report analysing the prevalence of ARV resistance which includes patients under HAART from Chile. Additionally, phylogenetic analysis of the PR-RT coding sequences reveals the presence of BF intersubtype recombinants.

Long-term monitoring of genotypic and phenotypic resistance to T20 in treated patients infected with HIV-1

The aim of this study was to investigate the susceptibility to T20 and the dynamics of amino acid changes in HR1 and HR2 of gp41 of HIV-1 obtained from plasma, peripheral blood mononuclear cells (PBMC), and primary isolates (PI) in four highly antiretroviral-experienced patients. These patients received T20 plus an antiretroviral regimen and were followed-up over a period of 40-72 weeks. In one non-responder patient, N43D substitution was detected at 12 weeks of treatment, in association with a value of T20-IC50 of 10 microg/ml (10-fold increase). Double mutations N42T + N43D were observed in plasma RNA at 32 weeks and remained detectable up to 16 weeks after the withdrawal of the drug. The S138A substitution in HR2 was observed in plasma RNA at 32 weeks, and both in plasma RNA and in PI DNA at 40 weeks, associated with an increase of the T20-IC50 to 25 microg/ml (25-fold increase). Mutations V101G and E137K, not reported previously, were also observed in the HR2 region. Whether these new substitutions play a role in T20 resistance needs to be examined. In three temporary responders, coinciding with viral load rebound, G36D, and N42T substitutions were observed at 12, 24, and 40 weeks. G36D mutation was associated with a value of T20-IC50 of 5 microg/ml. The HR2 S138A mutation was detected after the detection of HR1 substitutions and was associated with an increase in the level of T20-IC50 to 125 microg/ml (125-fold increase) All these data reinforce the role of gp41 amino acids 36-45 and the potential influence of the HR2 S138A mutation in the genotypic/phenotypic resistance to T20.

Isolation and biological characterization of HIV-1 BG intersubtype recombinants and other genetic forms circulating in Galicia, Spain

The biological characteristics of HIV-1 primary isolates of different recombinant forms (RFs) and non-B subtypes from Galicia, Spain, were investigated and the relationships between biological phenotype and evolution of infection were determined. Peripheral blood mononuclear cells (PBMCs) were obtained during the follow-up of 32 patients infected with HIV-1 non-subtype B genetic forms, characterized in partial sequences of pol (protease-reverse transcriptase) and env V3 region: 12 (37.5%) circulating RFs (CRFs), 9 (28.1%) unique RFs (URFs), and 11(34.4%) non-B subtypes. Primary isolates were obtained by coculture with donor PBMCs. Syncytium-inducing (SI) phenotype was examined in MT2 cell line and coreceptor use in GHOST and U87.CD4 cells. Fifty percent of tissue culture infective dose (TCID(50)) and viral phenotype based on V3 net charge and Geno2pheno(coreceptor) bioinformatic method were determined. Fifty-four HIV-1 primary isolates were obtained. CRF14_BG and BG URFs represented the largest group, being all SI/X4, independently of the CD4+ cell count, viral load, or the duration of infection. By contrast, 10 of 11 CRF02_AG viruses were NSI/R5. The prediction of co-receptor use was concordant with biological characterization in all NSI/R5 and in 23 of 26 SI/X4 isolates. The presence of SI/X4 or SI/X4,R5 isolates at early stages of the infection in addition to a decrease in CD4+ counts below 500 cells/microl between 2 and 6 years since diagnosis was observed in all patients infected with CRF14_BG and BG URFs. These data contrast with the usual progression in B subtype infections, in which SI/X4 viruses rarely predominate in the early years of HIV-1 infection.

Analysis of drug resistance-associated mutations in treatment-naïve individuals infected with different genetic forms of HIV-1 circulating in countries of the former Soviet Union

There are few data on drug resistance-associated mutations in the former Soviet Union since, studies have usually been focused on the env or gag genes for subtype information. This study examines the prevalence and patterns of resistance-associated mutations to reverse transcriptase and protease inhibitors (RTI, PRI) in 278 HIV-1-infected treatment-naïve subjects from countries of Eastern Europe, and defines characteristic polymorphisms of RT and PR sequences in HIV-1 subtype A viruses. Blood samples were collected between 1997 and 2004. Plasma RNA was used for PR-RT amplification by reverse transcription coupled with nested PCR and sequencing. Phylogenetic analysis was done with neighbor-joining trees and bootscanning. Analysis of drug resistance mutations, with Stanford University HIV Drug Resistance Database's algorithm, resulted in an overall prevalence of 12.9% resistance to RTI and 3.9% to PRI. The most frequent substitutions in the RT region were at positions 62 and 236. V77I substitution in PR was found in 47.8% of samples. Polymorphisms in subtype A sequences were identified. This is the first study reporting the prevalence and patterns of both PRI and RTI resistance-associated mutations in naïve HIV-1 infected patients from the former Soviet Union. These data underline the importance of genotypic resistance testing of chronically HIV-1-infected patients before initiating treatment, in order to select the most suitable drug regimen.

Natural resistance-associated mutations to Enfuvirtide (T20) and polymorphisms in the gp41 region of different HIV-1 genetic forms from T20 naive patients

BACKGROUND

The natural occurrence of primary resistance mutations in reverse transcriptase (RT) and protease (PR) genes of HIV-1 isolates from untreated patients has been reported and it may have important implications for the response to drug treatment. It is predictable that the same occurs in the HR1 region of gp41 sequence from patients who have never received T20 therapy, and in this regard it would be important to know not only the mutation frequencies at HR1 region but also the natural polymorphisms at resistance-associated positions present in the absence of this drug.

OBJECTIVES

The objectives of this study are to investigate the existence of natural resistance-associated mutations to T20 in HR1 gp41 region corresponding to different HIV-1 genetic forms from T20 naive patients and to determine their prevalence.

STUDY DESIGN

Two hundred HIV-1 gp41 sequences were included: subtype B: 164 (81.3%); subtype A: 15 (8.2%); subtype G: 10 (4.6%); subtype F: 6 (3.5%); subtype C: 3 (1.8%); subtype K: 1 (0.6%); and subtype D: 1 (0.6%). We analyzed the resistance-associated mutations previously described: Q32H/R, G36D/S, I37V, V38A/M, Q39R/H, Q40H, N42T/D/Q/H, N43D/S/K/Q, L44M, L45M, R46M and V69I.

RESULTS

Natural resistance mutations to T20 were found at a high frequency: 10.5%, corresponding to 9.1% in subtype B and 16.7% in non-B subtype samples. Polymorphisms were more frequent in non-B and recombinant forms than in subtype B (p<0.001). Different substitutions were related to subtypes: N42S in subtypes A, B, G and C, but not in F, Q56R in subtype A from CRF02_AG, and L54M in subtype B from CRF14_BG.

CONCLUSIONS

To our knowledge this is the first study describing natural-resistance to T20 among different HIV-1 subtypes, warranting a study of the biological significance of this mutations and their clinical relevance. The detection of differences between subtypes may have an influence on the rate and patterns of resistance in patients undergoing T20 treatment.

Analysis of discrepancies in the interpretation of antiretroviral drug resistance results in HIV-1 infected patients of Basque Country, Spain

BACKGROUND

Genotypic and phenotypic analysis of HIV-1 resistance mutations constitute one important point for providing guidelines in the choice of antiretroviral regimens and to design lines of rescue treatment for patients holding HIV-1 drug-resistant variants. However, some levels of discordance among them has been described.

OBJECTIVES

(i) To compare the genotypic analysis of resistance mutations to reverse transcriptase (RT) and protease (PR) inhibitors by Stanford HIVdb program (http://hivdb.stanford.edu) (St-HIVdb), and genotype with quantitative phenotypic analysis (Virtual Phenotype, VircoNET). (ii) To identify drug resistance mutations associated with discrepant results.

STUDY DESIGN

Five hundred HIV-1 infected patients were included in this study. RNA was extracted from plasma. RT and PR regions were amplified and sequenced using ABI-Prism DNA sequencing system. Sequences were corrected and assembled with Seqman and Bioedit computer programs. The corrected sequences were submitted to the Stanford HIV-Seq program (http://hivdb.stanford.edu) and to Virtual Phenotype (VircoNET).

RESULTS

Discrepant cases were considered if results were high or intermediate resistant by Stanford HIV-Seq program and susceptible by Virtual Phenotype, being detected as follows: (i) nucleoside RT inhibitors (NRT): 31.7% (ABC), 31% (d4T), 29.5% (ddC), 27.6% (ddI), 14.3% (TDF) and 11.3% (ZDV) and to PR inhibitors: 8.8% (SQV), 5% (APV), 3.8% (NFV) and 3.2% (IDV). These discrepant results were related to the presence of thymidine analogue mutations (TAMs) and also to key resistance mutations to NRT inhibitors: 65R, 69D/N, 74V/I, 184V/I and 215Y/F. (ii) PR inhibitors: 82A/F/T/S, 84I and 90M. Concordant results were considered when the interpretations by both programs were coincident, being higher than 96.7% for non-NRT inhibitors.

CONCLUSIONS

The detection of discrepant results to NRT inhibitors and PR inhibitors, including the analysis of sequences with key resistant mutations to some drugs, means that further investigation is necessary in order to establish which is the best interpretation system as antiretroviral therapy guide.

The analysis of near full-length genome sequences of human immunodeficiency virus type 1 BF intersubtype recombinant viruses from Chile, Venezuela and Spain reveals their relationship to diverse lineages of recombinant viruses related to CRF12_BF

Human immunodeficiency virus type 1 (HIV-1) BF intersubtype recombinant viruses are common in Argentina and Uruguay, where CRF12_BF and related recombinants are frequently found, and, in a lower proportion, in Brazil. Full-length genome sequences have been characterized in several of these recombinant viruses. Here, we analyze six newly derived near full-length genome sequences of BF recombinant viruses, three from Chile, one from Venezuela and two from Spain. Five of them had known epidemiological links to Argentina. Genomes were amplified by PCR from plasma RNA or from peripheral blood mononuclear cells' DNA. Mosaic structures and phylogenetic relationships were analyzed by bootscanning, neighbour-joining phylogenetic trees and by examination of subtype signature nucleotides. One virus from Spain had a mosaic structure fully coincident with CRF12_BF. The others had unique mosaic structures, except the viruses from two Chilean sisters infected vertically from the same mother, who showed identical recombination patterns. Each of the unique recombinants had one to six breakpoints coincident with CRF12_BF and three also had two or three breakpoints coincident with a previously characterized unique recombinant from Argentina (A025) related to CRF12_BF. A phylogenetic tree of concatenated subtype F segments supported the relationship of five recombinants with CRF12_BF. In trees of partial subtype F and B segments, four recombinants clustered with A025. The examination of CRF12_BF signature amino acids and nucleotides supported the common ancestry of all the analyzed viruses. Based on these results, a model of generation of HIV-1 BF recombinants of Argentinean ancestry by successive rounds of recombination along diverse lineages deriving from a common BF recombinant ancestor related to CRF12_BF is proposed.

Involvement of 5-HT1A receptors in behavioural effects of the cannabinoid receptor agonist CP 55,940 in male rats

We have studied the possible interaction between the cannabinoid receptor agonist CP 55,940 (1 and 50 microg/kg) and the 5-HT1A receptor antagonist WAY 100635 (1 mg/kg) in the modulation of plus-maze and holeboard activity in Wistar adult male rats. In the plus-maze, the higher dose of CP 55,940 induced an anxiogenic-like effect, whereas the lower dose induced anxiolytic-like responses. The 5-HT1A antagonist, which was silent in this test, attenuated the anxiogenic, but not the anxiolytic, effect of CP 55,940. In the holeboard, the higher dose of CP 55,940 significantly decreased head-dipping duration, and WAY 100635, which did not affect exploratory head-dipping when administered alone, antagonized this effect. The administration of WAY 100635 significantly increased grooming behaviour, and this effect was inhibited by the two doses of CP 55,940, which did not exert any effect, per se, on this parameter. We provide the first evidence implicating 5-HT1A receptors in anxiety-related behavioural responses to a cannabinoid agonist.

Near full-length genome characterization of an HIV type 1 CRF05_DF virus from Spain

We report the near full-length sequence characterization of a HIV-1 DF intersubtype recombinant virus from Spain, X492, directly amplified from peripheral blood mononuclear cells' DNA. This isolate shares an identical mosaic structure and exhibits consistent phylogenetic clustering along the genome with VI961, a previously characterized DF recombinant virus. By contrast, VI1310, which may represent the same recombinant form as VI961 (CRF05_DF), is only partially homologous to VI961 and X492. Of three additional DF recombinant viruses previously characterized in gag-pol, only one, VI1267, clusters uniformly with VI961 and X492; the other two branch separately in a segment of pol. These results allow us to define an HIV-1 circulating recombinant form (CRF05_DF), characterized in near full-length genomes of two isolates (VI961 and X492) and in partial gag-pol sequences of a third virus (VI1267). Three other reported DF recombinant viruses, including the fully sequenced VI1310, exhibit incomplete homology to VI961 and X492.

High incidence of non-B and recombinant HIV-1 strains in newly diagnosed patients in Galicia, Spain: study of genotypic resistance

The objectives of this study are to describe the incidence of non-B and recombinant HIV-1 strains in newly diagnosed HIV-1 infections in Galicia, northwest of Spain, during a 2-year period (May 2000 to June 2002), and the frequency of resistance-associated mutations in reverse transcriptase (RT) and protease (PR) genes, analysing the polymorphisms more frequently detected in non-B and recombinant viruses. All newly diagnosed HIV-1-infected patients attending the nine public hospitals of the seven main cities of Galicia were included in this study. RT, PR and V3 regions from HIV-1 RNA plasma were amplified and sequenced, being the corrected sequences sent to the Stanford HIV RT and Protease Sequence Database. Nineteen of 85 patients (22.3%) were infected by non-B or recombinant viruses: three subtype C, two G, one F1, one Dpol/A1V3, five CRF02_AG, one CRF14_BG, five BGpol/BV3 and one UKpol/UV3 (U, unknown fragment). Eleven of these 19 patients (57.9%) were foreign individuals living in Galicia infected through heterosexual contact, and the other eight (42.1%) were Spanish intravenous drug users who had shared injection equipment. Five of 85 patients (5.9%), all infected with B subtype viruses, showed resistance-associated mutations in RT (M184V, M41L, L210W, T215Y/D and K219Q). In one patient (1.2%) infected with a subtype G strain, resistance-associated mutations in PR (K20I+M36I+M46I+V82I) were detected. In subtype B viruses resistance mutations in PR were not detected. Several polymorphisms in RT: D123S, Q174K, D177E, T200A, V245Q, and PR: I13V, K20I, M36I, R41K, H69K, L89M were detected more frequently in non-B and recombinants than in B strains (P<0.01 to P<0.001). This study reports a high incidence (22.3%) of newly diagnosed patients infected by different non-B and recombinant HIV-1 strains, in a geographical area of Spain, showing also a high frequency of polymorphisms in RT and PR genes.

High Incidence of Non-B and Recombinant HIV-1 Strains in Newly Diagnosed Patients in Galicia, Spain: Study of Genotypic Resistance

The objectives of this study are to describe the incidence of non-B and recombinant HIV-1 strains in newly diagnosed HIV-1 infections in Galicia, northwest of Spain, during a 2-year period (May 2000 to June 2002), and the frequency of resistance-associated mutations in reverse transcriptase (RT) and protease (PR) genes, analysing the polymorphisms more frequently detected in non-B and recombinant viruses. All newly diagnosed HIV-1-infected patients attending the nine public hospitals of the seven main cities of Galicia were included in this study. RT, PR and V3 regions from HIV-1 RNA plasma were amplified and sequenced, being the corrected sequences sent to the Stanford HIV RT and Protease Sequence Database. Nineteen of 85 patients (22.3%) were infected by non-B or recombinant viruses: three subtype C, two G, one F1, one Dpol/A1V3, five CRF02_AG, one CRF14_BG, five BGpol/BV3 and one UKpol/UV3 (U, unknown fragment). Eleven of these 19 patients (57.9%) were foreign individuals living in Galicia infected through heterosexual contact, and the other eight (42.1%) were Spanish intravenous drug users who had shared injection equipment. Five of 85 patients (5.9%), all infected with B subtype viruses, showed resistance-associated mutations in RT (M184V, M41L, L210W, T215Y/D and K219Q). In one patient (1.2%) infected with a subtype G strain, resistance-associated mutations in PR (K20I+M36I+M46I+V82I) were detected. In subtype B viruses resistance mutations in PR were not detected. Several polymorphisms in RT: D123S, Q174K, D177E, T200A, V245Q, and PR: I13V, K20I, M36I, R41K, H69K, L89M were detected more frequently in non-B and recombinants than in B strains ( P<0.01 to P<0.001). This study reports a high incidence (22.3%) of newly diagnosed patients infected by different non-B and recombinant HIV-1 strains, in a geographical area of Spain, showing also a high frequency of polymorphisms in RT and PR genes.

High HIV-1 genetic diversity in Cuba

BACKGROUND

HIV-1 subtype B is largely predominant in the Caribbean, although other subtypes have been recently identified in Cuba.

OBJECTIVES

To examine HIV-1 genetic diversity in Cuba.

METHODS

The study enrolled 105 HIV-1-infected individuals, 93 of whom had acquired the infection in Cuba. DNA from peripheral blood mononuclear cells was used for polymerase chain reaction amplification and sequencing of pol (protease-reverse transcriptase) and env (V3 region) segments. Phylogenetic trees were constructed using the neighbour-joining method. Intersubtype recombination was analysed by bootscanning.

RESULTS

Of the samples, 50 (48%) were of subtype B and 55 (52%) of diverse non-B subtypes and recombinant forms. Among non-B viruses, 12 were non-recombinant, belonging to six subtypes (C, D, F1, G, H and J), the most frequent of which was subtype G (n = 5). The remaining 43 (78%) non-B viruses were recombinant, with 14 different forms, the two most common of which were Dpol/Aenv (n = 21) and U(unknown)pol/Henv (n = 7), which grouped in respective monophyletic clusters. Twelve recombinant viruses were mosaics of different genetic forms circulating in Cuba. Overall, 21 genetic forms were identified, with all known HIV-1 group M subtypes present in Cuba, either as non-recombinant viruses or as segments of recombinant forms. Non-B subtype viruses were predominant among heterosexuals (72%) and B subtype viruses among homo- or bisexuals (63%).

CONCLUSION

An extraordinarily high diversity of HIV-1 genetic forms, unparalleled in the Americas and comparable to that found in Central Africa, is present in Cuba.

Molecular epidemiology of HIV-1 genetic forms and its significance for vaccine development and therapy

Since their initial expansion in human beings roughly seven decades ago in central Africa, the HIV-1 pandemic strains have diversified extensively through mutation and recombination. 24 circulating genetic forms of the main HIV-1 group are presently recognised, including 11 subtypes or sub-subtypes and 13 circulating recombinant forms. New genetic forms are being introduced in different areas of the world, changing the molecular epidemiology of the infection. It is generally agreed that the control of the HIV-1 pandemic requires the development of vaccines that efficiently protect against the range of HIV-1 genetic forms. The introduction of effective antiretroviral therapies in areas of high HIV-1 prevalence may also contribute to the control of the pandemic, as has been documented in developed countries. Efficient targeting of the extensive genetic diversity of HIV-1 constitutes one of the major challenges in present efforts against the pandemic, although the significance of HIV-1 genetic forms for vaccine development and therapy remains to be defined.

Identification of a newly characterized HIV-1 BG intersubtype circulating recombinant form in Galicia, Spain, which exhibits a pseudotype-like virion structure

We recently reported the finding of phylogenetically related HIV-1 BG intersubtype recombinant and G subtype nonrecombinant viruses circulating among injecting drug users in the region of Galicia in northwestern Spain. Here, we report the characterization of near full-length genome sequences of nine of these viruses (seven BG recombinant and two of nonrecombinant G subtype), obtained from epidemiologically unlinked individuals. Bootscan analysis reveals that six recombinant viruses share an identical mosaic structure, with two intersubtype breakpoints delimiting a B subtype segment comprising most of Env gp120 and the external portion of Env gp41, with the remaining portions of the genome being of subtype G, thus mimicking a pseudotype virion structure. The seventh BG recombinant virus exhibits breakpoints in env coincident with the other BG viruses but contains additional B subtype segments in gag and pol. In phylogenetic trees of complete genomes and of the B subtype segment of env, all seven BG viruses group in a monophyletic cluster. G subtype portions of the BG viruses group uniformly with the newly derived nonrecombinant G subtype viruses of Galicia in bootscan analysis, which points to the locally circulating G subtype strain as parental of the recombinants. These results allow us to define a new HIV-1 circulating recombinant form (CRF14_BG), the first reported to originate in Western Europe.

Genotypic resistance mutations to antiretroviral drugs in HIV-1 B and non-B subtypes from Cuba

OBJECTIVES

To determine the prevalence of drug resistance and to analyze the subtyping in HIV-1 samples from Cuba.

METHODS

From an estimated total number of 1,950 HIV-1-infected persons in Cuba, a sample of 103 patients were studied, 76 of whom had received drug treatment for HIV and 27 who had not. The RNA plasma viral load was measured, and automated sequencing was used to assess resistance mutations to reverse transcriptase inhibitors (RTIs) and to protease inhibitors (PIs). Subtyping in the V3 region was performed using heteroduplex mobility assay (HMA). In order to corroborate the HMA results, sequencing of env (C2-V3-C3) was done with one-third of the samples in each of the subtype groups detected by HMA.

RESULTS

Out of the 103 samples, 81 of them (78.6%) were classified as subtype B, 19 (18.5%) as subtype A, and 3 (2.9%) as subtype C. The prevalence of resistance mutations was 26.2% to RTIs, none to PIs alone, and 3.9% to both categories of drugs. The prevalence of resistance to nucleoside RTIs (NRTIs) was 27.6% in treated patients and 7.4% in the untreated patients, and for nonnucleoside RTIs (NNRTIs) it was 5.3% and 0%, respectively. Among treated patients a low frequency (2.6%) of dual resistance to zidovudine (ZDV) plus lamivudine (3TC) and abacavir (ABC) was detected, and multidrug resistance to NRTIs was not found. In relation to PIs together with RTIs, the prevalence of resistance was 5.3% for treated patients and 0% for untreated patients.

CONCLUSIONS

Even though Cuba is generally considered an area where subtype B is dominant, we detected a high proportion of non-B subtype viruses. The low prevalence of resistance mutations to RTIs and PIs reflects the delay in introducing these drugs to Cuba. Multidrug resistance to RTIs was not found, so, as of now, the use of these drugs continues to be an option for Cuban patients.

Detection and quantification of multiple drug resistance mutations in HIV-1 reverse transcriptase by an oligonucleotide ligation assay

OBJECTIVES

To develop an assay for the early detection and quantification of minor human immunodeficiency virus-1 populations bearing multiple drug resistance (MDR) mutations.

STUDY DESIGN/METHODS

The oligonucleotide ligation assay (OLA) is based on ligation of probe and detector oligonucleotides annealed to a polymerase chain reaction amplicon strand with detection by an enzyme immunoassay. In OLA-MDR, oligonucleotides were designed to detect MDR mutations. The method was validated with wild-type and MDR mutant clones mixed at different proportions.

RESULTS

K103N mutants were detected as minor populations (5%-30%) by OLA in 6 of 18 samples from patients treated with nonnucleoside reverse transcription inhibitors and classified as wild type by sequencing. In one patient, the kinetics of the increase of MDR mutants could be followed in sequential samples, with K103N being detected earlier by OLA than by sequencing. Q151M mutants were detected as minor populations (13%-24%) by OLA but not by sequencing in 4 samples.

CONCLUSIONS

Oligonucleotide ligation assay MDR exhibits higher sensitivity than sequencing for detection of minor MDR mutant populations.

Analysis of HIV type 1 protease and reverse transcriptase sequences from Venezuela for drug resistance-associated mutations and subtype classification: a UNAIDS study

We report the first study on prevalence of antiretroviral drug-associated resistance mutations in Venezuela. Protease and reverse transcriptase (RT) coding regions were analyzed in DNA samples obtained from 100 HIV-1-infected individuals. Primary resistance mutations to RT inhibitors were identified in 26% of patients treated with these drugs. Transmission of HIV-1-resistant strains was detected in a drug-naive patient (3%). Primary resistance mutations to protease inhibitors (PIs) were present in 9% of the 44 PI-treated patients and in 1 PI-naive individual. Phylogenetic analysis of these samples has resulted in the most extensive survey, to date, of HIV-1 genetic forms circulating in Venezuela. Ninety-nine samples clustered with subtype B, and 1 individual harbored the first B/F recombinant virus reported in Venezuela, with protease clustering with subtype F and RT with subtype B. In addition, this isolate had a new insertion (Glu-34 duplication) in the protease gene.

HIV-1 genetic diversity in Galicia Spain: BG intersubtype recombinant viruses circulating among injecting drug users

BACKGROUND

The HIV-1 epidemics in Western Europe are dominated by B subtype viruses. Non-B subtype is largely restricted to individuals infected outside of Europe and to their direct contacts and is generally acquired by the heterosexual route.

METHODS

Protease and a segment of reverse transcriptase were amplified and sequenced from plasma RNA in 451 individuals from seven cities of Galicia, north-western Spain. Subtype sequence homologies were determined using the BLAST algorithm. Non-B sequences were examined by phylogenetic analysis and intersubtype recombination by bootscanning. The env V3 region was analysed in all non-B and in 38 B subtype viruses.

RESULTS

Ten different non-B genetic forms were identified in 20 (4.4%) individuals. Subtypes were concordant between pol and V3 in five viruses; 14 (70%) infections were with intersubtype recombinant viruses, and one individual had a dual B+G infection. Seven recombinant viruses were phylogenetically related to five reported recombinant forms. Three non-recombinant G and six recombinant BG viruses formed a monophyletic cluster for pol. All but three individuals with non-B infections were native Spanish. Only 6 of 16 individuals referred to sexual contacts with sub-Saharan Africans. Twelve (60%) non-B subtype infections, including all with G and BG viruses, were in injecting drug users (IDU).

CONCLUSIONS

Non-B subtype viruses were identified in 4.4%, with a high diversity of genetic forms, including 70% infections with intersubtype recombinant viruses. The majority of individuals with non-B infections were IDU, most of them without known contacts with non-European sources, and among whom BG recombinant viruses are circulating.

Single- and multidrug resistance mutations to reverse transcriptase and protease inhibitors: human immunodeficiency virus type 1-infected patients from two geographical areas in Spain. Spanish Groups for Antiretroviral Resistance Studies

OBJECTIVES

To describe the prevalence of genotypic resistance mutations, including single and multidrug resistance (MDR) to reverse transcriptase (RT) and protease (PR) inhibitors in treated and untreated patients from two geographical areas in Spain (Madrid and Galicia).

STUDY DESIGN/METHODS

Resistance mutations to RT inhibitors were studied by line probe assay (LiPA) or by automated sequencing in 468 patients (Madrid, 268; Galicia, 200), and resistance mutations to PR inhibitors were studied by automated sequencing in 295 patients (Madrid, 85; Galicia, 210).

RESULTS

The proportion of resistance mutations in treated and untreated patients results were higher by the LiPA method than by sequencing. By sequencing, we detected resistance mutations to nucleoside analogue RT (NRT) inhibitors and NRT inhibitors plus nonnucleoside RT (NNRT) inhibitors in 35.4% and 17.2% of treated patients, respectively. We also detected MDR to zidovudine plus lamivudine in 13.9% of treated patients from Galicia, in 1.7% from Madrid (p < 0.001), and in 1.5% of untreated patients from Galicia. Also, we detected MDR to NRT inhibitors in 3.8% and to NNRT inhibitors in 9.1%. We found resistance mutations to PR inhibitors in 38.1% of treated patients and in 0.9% of untreated patients.

CONCLUSIONS

These findings reinforce the usefulness of testing for resistance mutations in some cases to evaluate their prevalence in a given population and in the follow-up of treated patients.

Evaluation of mixtures of wild-type HIV-1 and HIV-1 with resistance point mutations against reverse transcriptase inhibitors

The presence of resistance-related mutations in 185 serial proviral DNA samples from 108 HIV-infected patients was monitored using the line probe assay (LiPA). The proportions of wild-type and mutant virus in each sample were determined. Subsequent samples from the same patient were analysed. Resistance mutations were detected in 58 of 108 patients studied (53.7%), 53 of 73 (72.6%) treated with antivirals and 5 of 35 (14.2%) untreated. The mutations were against zidovudine (51), lamivudine (1), zidovudine and lamivudine (4), zidovudine and zalcitabine (1) and zidovudine and didanosine (1). Among the 58 patients with resistant virus, 168 related mutations were observed: 161 to zidovudine (90 in codon 70, 25 in codon 41 and 46 in codon 215), 5 to lamivudine (codon 184), 1 to zalcitabine (codon 69) and 1 to didanosine (codon 74). Mixtures of wild-type and resistant mutants were detected in 76 of 90 (84.4%) mutated at codon 70, 28 of 46 (60.8%) mutated at codon 215 and in 21 of 25 (84%) mutated at codon 41. The mutations at codon 184 were mixtures of wild-type and resistant in 4 of 5 samples. The agreement between LiPA and sequencing was 96.5%. LiPA was more sensitive for the detection of mutants that were present at low frequency. The analysis of sequential samples from the same patient allowed evaluation of the dynamics of appearance of the resistant mutants.

Improved conditions for extraction and amplification of human immunodeficiency virus type 1 RNA from plasma samples with low viral load

OBJECTIVES

We attempted to define optimal conditions for amplification of low copy number HIV-1 RNA sequences in plasma samples, applying improved conditions for nucleic acid extraction and amplification.

METHODS

Several methodologic parameters were evaluated, including methods of RNA extraction, volumes of plasma samples, proportion of extracted RNA used as a template for amplification, and reverse transcriptase-DNA polymerase enzyme combination employed in cDNA synthesis and polymerase chain reaction amplification.

RESULTS

With this improved assay, we were able to obtain sufficient amounts of amplified material for direct sequencing in 97% of all plasma samples in our study, including 88% of samples with viral loads <80 copies/mL, 78% of samples with viral loads <50 copies/mL, and even 2 (67%) of 3 samples with <20 copies/mL.

CONCLUSIONS

This procedure could be useful for testing resistance mutations in patients undergoing highly active antiretroviral therapy, in which the viral load is commonly <400 copies/mL, and even if it is <20 RNA copies/mL.

Sequence analysis of the polymerase domain of HIV-1 reverse transcriptase in naive and zidovudine-treated individuals reveals a higher polymorphism in alpha-helices as compared with beta-strands

We report a statistical analysis of genetic heterogeneity of the reverse transcriptase (RT)-coding region of human immunodeficiency virus type 1. Both newly determined sequences and sequences contained in the data banks have been examined. For the calculations, the viral samples and the regions within the RT molecule were divided in two groups. The viral samples were split into those from patients not subjected to antiretroviral therapy and those from patients treated with zidovudine (AZT, 3'-azido-3'-deoxythymidine) alone or in combination with other RT inhibitors. The RT-coding region was divided into segments encoding beta-strands and segments encoding alpha-helices. A significantly lower heterogeneity was observed in beta-strands relative to the alpha-helix coding segments. Application of the D test of Tajima has provided evidence of operation of negative (or purifying) selection in sequences from viruses of patients not subjected to antiretroviral treatment as well as in treated patients. In the group of untreated individuals, regions encoding beta-strands are subjected to stronger negative selection than those encoding alpha-helices. It is likely that the observed differences reflect stronger functional constraints in beta-strands than in alpha-helices of RT.

Evaluation of Mixtures of Wild-Type HIV-1 and HIV-1 with Resistance Point Mutations against Reverse Transcriptase Inhibitors

The presence of resistance-related mutations in 185 serial proviral DNA samples from 108 HIV-infected patients was monitored using the line probe assay (LiPA). The proportions of wild-type and mutant virus in each sample were determined. Subsequent samples from the same patient were analysed.

Resistance mutations were detected in 58 of 108 patients studied (53.7%), 53 of 73 (72.6%) treated with antivirals and 5 of 35 (14.2%) untreated. The mutations were against zidovudine (51), lamivudine (1), zidovudine and lamivudine (4), zidovudine and zalcitabine (1) and zidovudine and didanosine (1). Among the 58 patients with resistant virus, 168 related mutations were observed: 161 to zidovudine (90 in codon 70, 25 in codon 41 and 46 in codon 215), 5 to lamivudine (codon 184), 1 to zalcitabine (codon 69) and 1 to didanosine (codon 74). Mixtures of wild-type and resistant mutants were detected in 76 of 90 (84.4%) mutated at codon 70, 28 of 46 (60.8%) mutated at codon 215 and in 21 of 25 (84%) mutated at codon 41. The mutations at codon 184 were mixtures of wild-type and resistant in 4 of 5 samples. The agreement between LiPA and sequencing was 96.5%. LiPA was more sensitive for the detection of mutants that were present at low frequency. The analysis of sequential samples from the same patient allowed evaluation of the dynamics of appearance of the resistant mutants.

Epidemiologic investigation of an oil-associated pneumonic paralytic eosinophilic syndrome in Spain

From May 1 to December 26, 1981, a previously undescribed illness caused 277 deaths and the hospitalization of 12,656 persons in Spain. The disease was characterized by pneumonitis, eosinophilia, and marked loss of muscle mass and function. A succession of case-control studies was done in the town of Las Navas del Marqués (province of Avila) located 47 miles northeast of Madrid and with a population of 4009 people. The studies confirmed the association between illness and consumption of an illegally sold cooking oil. Other risk factors identified in the linear logistic regression analysis included involvement in various kitchen activities, increased average time spent inside the house, and the purchase of cooking oil from a specific street vendor. Although the oil was found to be a mixture of vegetable and animal fats contaminated with aniline and anilide-oil complexes, the specific etiologic mechanism of the disease has not been determined.