Genetic Diversity Of HIV-1 Strains Research Articles

New infections and HIV-1 subtypes among febrile persons and blood donors in Oyo State, Nigeria.

There were approximately 37.9 million persons infected with HIV in 2018 globally, resulting in 770,000 deaths annually. Over 50% of this infection and deaths occur in sub-Saharan Africa, with countries like Nigeria being seriously affected. Nigeria has one of the highest rates of new infections globally. To control HIV infection in Nigeria, there is a need to continually screen high-risk groups for early HIV infection and subtypes using very sensitive methods. In this study, new HIV-1 infection and circulating HIV-1 subtypes among febrile persons and blood donors were determined. Performance characteristics of three commercial EIA kits were also evaluated. In total, 1028 participants were recruited for the study. New HIV-1 infection and subtypes were determined using enzyme immunoassays and molecular techniques, respectively. Sensitivity, specificity, predictive values, and agreements were compared among the EIA kits using PCR-confirmed HIV-positive and negative samples. The overall prevalence of HIV infection in this study was 5.35%. The rate of new HIV infection was significantly different (p < .03674) among 1028 febrile persons (Ibadan: 2.22%; Saki: 1.36%) and blood donors (5.07%) studied. Three subtypes, CRF02_AG, A, and G, were found among those with new HIV infection. Whereas the commercial ELISA kits had very high specificities (94.12%,100%, and 100%) for HIV-1 detection, Alere Determine HIV-1 antibody rapid kit had the lowest sensitivity score (50%). Genetic diversity of HIV-1 strains among infected individuals in Oyo State, Nigeria, is still relatively high. This high level of diversity of HIV-1 strains may impactthe reliability of diagnosis of the virus in Nigeria and other African countries where many of the virus strains co-circulate.

Characterization of HIV-1 subtypes and transmitted drug resistance among treatment-naive HIV-infected individuals in Zhejiang, China, 2014-2017.

In recent years, transmitted drug resistance (TDR) has adversely impacted upon first-line therapy for HIV-infected individuals. To understand the current subtype distribution and TDR level in Zhejiang, China we performed phylogenetic analysis and genotypic drug resistance testing of treatment-naive HIV-infected individuals. A total of 153 HIV-1 Pol genes were successfully amplified. The distribution of HIV-1 genotypes was as follows: CRF01_AE (43.8%); CRF07_BC (37.9%); subtype B/B' (7.2%); CRF08_BC (5.2%); and others (5.9%). Drug resistance analysis demonstrated that 11.1% of isolates contained at least one NRTI or NNRTI resistance-associated mutations while 2.0% were identified to be resistant to PIs. These findings enhance our understanding of the genetic diversity of HIV-1 strains circulating in Zhejiang and provide some guidelines for HIV initial treatment therapy.

HIV-1 Genetic Diversity in Northeastern Brazil: High Prevalence of Non-B Subtypes.

The Northeastern Brazilian region has experienced a constant increase in the number of newly reported AIDS cases over the last decade, but the genetic diversity of HIV-1 strains currently disseminated in this region remains poorly explored. HIV-1 pol sequences were obtained from 140 patients followed at outpatient clinics from four Northeastern Brazilian states (Alagoas, Bahia, Ceará, and Piauí) between 2014 and 2015. Subtype B was the most prevalent HIV-1 clade (72%) detected in the Northeastern region, followed by subtypes F1 (6%), C (5%), and D (1%). The remaining strains (16%) displayed a recombinant structure and were classified as follows: BF1 (11%), BC (4%), BCF1 (1%), and CRF02_AG like (1%). The 20 HIV-1 BF1 and BC recombinant sequences detected were distributed among 11 lineages classified as follows: CRF28/29_BF like (n = 5), CRF39_BF like (n = 1), URF_BF (n = 9), and URF_BC (n = 5). Non-B subtypes were detected in all Northeastern Brazilian states, but with variable prevalence, ranging from 16% in Ceará to 55% in Alagoas. Phylogenetic analyses support that subtype D and CRF02_AG strains detected in the Northeastern region resulted from the expansion of autochthonous transmission networks, rather than from exogenous introductions from other countries. These results reveal that HIV-1 epidemic spreading in the Northeastern Brazilian region comprised by multiple subtypes and recombinant strains and the molecular epidemiologic pattern in this Brazilian region is much more complex than originally estimated.

Genetic characterization and antiretroviral resistance mutations among treatment-naive HIV-infected individuals in Jiaxing, China.

The aim of this study was to characterize HIV-1 genotypes and antiretroviral resistance mutations among treatment-naive HIV-infected individuals in Jiaxing, China. The HIV-1 partial polymerase (pol) genes in 93 of the 99 plasma samples were successfully amplified and analyzed. Phylogenetic analysis revealed the existence of five HIV-1 genotypes, of which the most prevalent genotype was CRF01_AE (38.7%), followed by CRF07_BC (34.4%), CRF08_BC (16.1%), subtype B/B’ (5.4%), and CRF55_01B (2.1%). Besides, three types of unique recombination forms (URFs) were also observed, including C/F2/A1, CRF01_AE/B, and CRF08_BC/CRF07_BC. Among 93 amplicons, 46.2% had drug resistance-associated mutations, including 23.7% for protease inhibitors (PIs) mutations, 1.1% for nucleoside reverse transcriptase inhibitors (NRTIs) mutations, and 20.4% for non-nucleoside reverse transcriptase inhibitors (NNRTIs) mutations. Six (6.5%) out of 93 treatment-naive subjects were identified to be resistant to one or more NNRTIs, while resistance to NRTIs or PIs was not observed. Our study showed the genetic diversity of HIV-1 strains circulating in Jiaxing and a relative high proportion of antiretroviral resistance mutations among treatment-naive patients, indicating a serious challenge for HIV prevention and treatment program.

Genetic diversity and transmission networks of HIV-1 strains among men having sex with men (MSM) in Lomé, Togo

Understanding the HIV epidemic in key populations is important. Today only scarce information is available on HIV-1 strains that circulate in men having sex with men (MSM) in sub-Saharan Africa. Here, we studied for the first time the genetic diversity of HIV-1 strains circulating in the MSM population in Lomé, the capital city from Togo. The overall subtype/CRF distribution in pol (protease and/or partial reverse transcriptase (RT)) among the 79 HIV-1 strains from MSM was as follows: CRF02_AG (72%, n=57), subtype G (2.5%, n=2), sub-subtype A3 (1.3%, n=1), and unique recombinant forms (URF) (24%, n=19). Among the 19 URFs four different mosaic structures were observed, annotated as URF1 to URF4. Fifteen sequences (URF1) had the same mosaic structure in pol (G/CRF02_AG) and could represent a new circulating recombinant form (CRF). Phylogenetic analysis of the RT sequences showed that there were several introductions of CRF02_AG strains in the MSM population, however half of the CRF02_AG and all URF1 strains formed a separate, well-supported cluster suggesting one major introduction of CRF02_AG in the MSM population followed by efficient transmission and emergence of a possible new CRF. At least 40% of the strains fell into recent transmission chains involving two to seven MSM. Comparison with >950 HIV-1 sequences from previous studies in Togo showed intermixing of the HIV-1 epidemics between MSM and the general population. Moreover, an HIV-1 strain from a recently HIV-1 infected male patient from Germany, fell within a cluster of HIV-1 strains from MSM from Togo, illustrating recent exchange between MSM from Africa and people from other geographic regions. With growing evidence of the importance of MSM in the dynamic of the HIV epidemic in Africa there is an urgent need for appropriate interventions to limit HIV transmission in this population group.

Genetic Analyses of HIV-1 Strains Transmitted from Mother to Child in Northern Vietnam.

We previously reported mother-to-child transmission of HIV-1 in nine (6.7%) of 135 children on nevirapine prophylaxis in Vietnam. In the current study, we investigated the appearance and profile of antiretroviral drug (ARV) resistance mutations, the predicted coreceptor usage, and the genetic diversity of HIV-1 strains isolated from the eight pairs of HIV-1-infected mothers and their children, who were followed up to 12 months after birth. Portions of the pol and env C2V3 regions of the HIV-1 strains were analyzed genetically. HIV-1 CRF01_AE RNA was detected in four (50%) children at delivery. Y181C, a nevirapine resistance mutation, appeared in two (25%) children 1 and 3 months after birth, respectively. No ARV resistance mutation was detected in the mothers, though three mothers were on ARV prophylaxis. Five mothers and their children harbored CCR5-tropic (R5) viruses. Two mothers harbored both R5 and CXCR4-tropic (X4) viruses, but their children harbored only R5 viruses even though the X4 viruses were dominant in the mothers. In the remaining one mother, HIV-1 RNA was not amplified and her child harbored both R5 and X4 viruses at birth, but only X4 virus 12 months after delivery. The infants' viruses were more homogeneous than their mothers' viruses (mean distance: 0.5% vs. 1.1%, respectively). This is the first molecular epidemiological study of vertical HIV-1 infections in Vietnam. These findings may provide useful knowledge for the prevention of mother-to-child transmission of HIV-1 and the antiretroviral treatment of children in Vietnam.

Genotypic prediction of tropism of highly diverse HIV-1 strains from Cameroon.

BackgroundThe use of CCR5 antagonists involves determination of HIV-1 tropism prior to initiation of treatment. HIV-1 tropism can be assessed either by phenotypic or genotypic methods. Genotypic methods are extensively used for tropism prediction. However, their validation in predicting tropism of viral isolates belonging to group M non-B subtypes remains challenging. In Cameroon, the genetic diversity of HIV-1 strains is the broadest reported worldwide. To facilitate the integration of CCR5 antagonists into clinical practice in this region, there is a need to evaluate the performance of genotypic methods for predicting tropism of highly diverse group M HIV-1 strains.MethodsTropism of diverse HIV-1 strains isolated from PBMCs from Cameroon was determined using the GHOST cell assay. Prediction, based on V3 sequences from matched plasma samples, was determined using bioinformatics algorithms and rules based on position 11/25 and net charge applied independently or combined according to Delobel's and Garrido's rules. Performance of genotypic methods was evaluated by comparing prediction generated with tropism assigned by the phenotypic assay.ResultsSpecificity for predicting R5-tropic virus was high, ranging from 83.7% to 97.7% depending on the genotypic methods used. Sensitivity for X4-tropic viruses was fairly low, ranging from 33.3% to 50%. In our study, overall, genotypic methods were less able to accurately predict X4-tropic virus belonging to subtype CRF02_AG. In addition, it was found that of the methods we used the Garrido rule has the highest sensitivity rate of over 50% with a specificity of 93%.ConclusionOur study demonstrated that overall, genotypic methods were less sensitive for accurate prediction of HIV-1 tropism in settings where diverse HIV-1 strains co-circulate. Our data suggest that further optimization of genotypic methods is needed and that larger studies to determine their utility for tropism prediction of diverse HIV-1 strains may be warranted.

Deciphering the Complex Distribution of Human Immunodeficiency Virus Type 1 Subtypes among Different Cohorts in Northern Tanzania

BackgroundIncreased understanding of the genetic diversity of HIV-1 is challenging but important in the development of an effective vaccine. We aimed to describe the distribution of HIV-1 subtypes in northern Tanzania among women enrolled in studies preparing for HIV-1 prevention trials (hospitality facility-worker cohorts), and among men and women in an open cohort demographic surveillance system (Kisesa cohort).MethodsThe polymerase encompassing partial reverse transcriptase was sequenced and phylogenetic analysis performed and subtype determined. Questionnaires documented demographic data. We examined factors associated with subtype using multinomial logistic regression, adjusted for study, age, and sex.ResultsAmong 140 individuals (125 women and 15 men), subtype A1 predominated (54, 39%), followed by C (46, 33%), D (25, 18%) and unique recombinant forms (URFs) (15, 11%). There was weak evidence to suggest different subtype frequencies by study (for example, 18% URFs in the Kisesa cohort versus 5–9% in the hospitality facility-worker cohorts; adjusted relative-risk ratio (aRR) = 2.35 [95% CI 0.59,9.32]; global p = 0.09). Compared to men, women were less likely to have subtype D versus A (aRR = 0.12 [95% CI 0.02,0.76]; global p = 0.05). There was a trend to suggest lower relative risk of subtype D compared to A with older age (aRR = 0.44 [95% CI 0.23,0.85] per 10 years; global p = 0.05).ConclusionsWe observed multiple subtypes, confirming the complex genetic diversity of HIV-1 strains circulating in northern Tanzania, and found some differences between cohorts and by age and sex. This has important implications for vaccine design and development, providing opportunity to determine vaccine efficacy in diverse HIV-1 strains.

HIV Type 1 Genetic Diversity in Silesia, Poland: A Retrospective Analysis

To characterize the genetic diversity of HIV-1 strains circulating among patients with different transmission risk behaviors in Silesia, Poland, from the origin of the epidemic to the year 2004, we have sequenced and analyzed the p24 coding region of the gag gene and part of the pol gene covering the first 256 codons for the reverse transcriptase (RT). The proviral DNA was obtained from the 101 HIV-1-infected patients, 80 of whom (79.2%) were intravenous drug users (IDUs) and 21 of whom (20.8%) reported sexual transmission risk practices (STs) with 11 (10.9%) being heterosexuals and 10 (9.9%) being homosexual men, which corresponds to the population's epidemiological data. All of the investigated viral sequences were classified as HIV-1 subtype B with low genetic heterogeneity. There was an association between HIV-1 genetic diversity and the risk of virus transmission in the investigated population. The mean nucleotide distances were significantly lower among sequences derived from IDUs than among sequences obtained from STs. Additionally, strains present among IDUs, as opposed to viruses circulating among STs, were genetically more distinct from HIV-1 subtype B strains found in other populations worldwide. Our findings that HIV-1 strains circulating among IDUs were closely related to each other, but were distinct from viruses prevalent in other geographic regions, allow further tracing of the spread of these strains.

Characterization of HIV Type 1 Genetic Diversity Among South African Participants Enrolled in the AIDS Vaccine Integrated Project (AVIP) Study

The genetic diversity of HIV-1 strains circulating among HIV-1-infected South Africans was investigated in a cohort of 420 individuals enrolled as part of the AIDS Vaccine Integrated Project (AVIP) study. Representative samples (10%) were randomly selected from treatment-naive participants. Viral RNA was extracted for reverse transcriptase-initiated amplification and population-based sequencing of partial pol (encompassing protease and reverse transcriptase) and full-length integrase. Overall, HIV-1 sequences confirmed that 97.1% and 96.9% were HIV-1 subtype C in pol and integrase, respectively. Two participants were infected with unique A1/C and C/A1 recombinants in pol/integrase. Further pol sequence analysis identified mutation patterns associated with high level resistance to NNRTIs in two participants, whereas no primary mutations conferring resistance to integrase inhibitors were detected. The predominance of HIV-1 subtype C in South African populations is therefore confirmed in the AVIP cohort finalized for testing preventive or therapeutic vaccines against HIV-1 infection.

HIV-1 recombinants with multiple parental strains in low-prevalence, remote regions of Cameroon: Evolutionary relics?

BackgroundThe HIV pandemic disseminated globally from Central West Africa, beginning in the second half of the twentieth century. To elucidate the virologic origins of the pandemic, a cross-sectional study was conducted of the genetic diversity of HIV-1 strains in villagers in 14 remote locations in Cameroon and in hospitalized and STI patients. DNA extracted from PBMC was PCR amplified from HIV(+) subjects. Partial pol amplicons (N = 164) and nearly full virus genomes (N = 78) were sequenced. Among the 3956 rural villagers studied, the prevalence of HIV infection was 4.9%; among the hospitalized and clinic patients, it was 8.6%.ResultsVirus genotypes fell into two distinctive groups. A majority of the genotyped strains (109/164) were the circulating recombinant form (CRF) known to be endemic in West Africa and Central West Africa, CRF02_AG. The second most common genetic form (9/164) was the recently described CRF22_01A1, and the rest were a collection of 4 different subtypes (A2, D, F2, G) and 6 different CRFs (-01, -11, -13, -18, -25, -37). Remarkably, 10.4% of HIV-1 genomes detected (17/164) were heretofore undescribed unique recombinant forms (URF) present in only a single person. Nearly full genome sequencing was completed for 78 of the viruses of interest. HIV genetic diversity was commonplace in rural villages: 12 villages each had at least one newly detected URF, and 9 villages had two or more.ConclusionsThese results show that while CRF02_AG dominated the HIV strains in the rural villages, the remainder of the viruses had tremendous genetic diversity. Between the trans-species transmission of SIVcpz and the dispersal of pandemic HIV-1, there was a time when we hypothesize that nascent HIV-1 was spreading, but only to a limited extent, recombining with other local HIV-1, creating a large variety of recombinants. When one of those recombinants began to spread widely (i.e. became epidemic), it was recognized as a subtype. We hypothesize that the viruses in these remote Cameroon villages may represent that pre-epidemic stage of viral evolution.

A Study of HIV-1 Genetic Diversity in the Czech Republic: 1986-2007

The global HIV/AIDS epidemic consists of a number of regional epidemics caused by different HIV-1 subtypes prevailing in different regions. To study changes in genetic diversity of HIV-1 strains isolated in the Czech Republic (CR) over a more than twenty-year period (1986-2007). HIV-1 strains isolated in CR from 1986 to 2007 were subtyped by pol gene sequencing followed by phylogenetic analysis. The role of HIV-1 subtyping in molecular epidemiology was considered. Awide range of HIV-1 subtypes were found, with subtype B, into which 76.6% of 534 HIV-1 isolates were classified, being predominant during the whole study period. An increasing number of non-B subtypes A1, C, D, F1, G and some recombinant forms (CRF 01_AE, CRF 02_AG and CRF 06_cpx) were identified after 1990. The absolute predominance of subtype B among HIV-1 strains in the Czech Republic ended in 1991 when different non-B subtypes had been introduced into the country. The East-West migration is responsible for the introduction of HIV-1 subtypes prevalent in Eastern European and some Asian countries. Genetic analysis of HIV-1 isolates from a given region can be helpful in tracing the course of the HIV/AIDS epidemic.

Genetic characterization of human immunodeficiency virus type 1 from Beira, Mozambique

In this report, we examined the genetic diversity of HIV-1 strains circulating in the city of Beira, the second largest metropolitan area in Mozambique. A total of 131 blood samples, collected between August and October 2003 from antiretroviral-naïve individuals, were characterized with a combined approach consisting of heteroduplex mobility assay (HMA) subtyping for gag ( n = 74) and/or env ( n = 117) genes, and DNA sequence analysis of proviral env (C2V3C3, n = 52), LTR ( n = 30) and/or pol ( n = 43) genomic regions. Aside from the identification, by bootscanning analysis, of a viral strain with a C/A 1 mosaic C2V3C3 structure, classified as subtype A by env HMA, phylogenetic inference studies of the sequence data demonstrated the circulation of genetically diverse subtype C viruses, predominantly of the R5 type. Inspection of the LTR sequences revealed a pattern of structural and regulatory elements typical of subtype C, with 63.3% of the viruses showing three NF-κB binding sites. Analysis of the predicted protease sequences enabled us to detect a single primary mutation (I84V, n = 1) associated with resistance to protease inhibitors (PI), while secondary mutations were highly prevalent, some of them in combinations which may confer PI resistance. Although an unexpectedly high rate (11.6%) of reverse transcriptase key mutations (V75A, K103N, Y181C, M184I, or P236L) was detected in the sequences analyzed, our data suggest the non-epidemic circulation of resistant viruses, and the absence of multi-class drug resistant viral strains.

HIV-1 subtypes and recombinants in the Republic of Congo

To document the actual genetic diversity of HIV-1 strains in the Republic of Congo, 114 HIV-1 positives persons were sampled in 2003 and 2004 after their informed consent. They were attending the teaching hospital, the reference health center in Makelekele, Brazzaville and the regional hospital centers in Pointe-Noire, Gamboma and Ouesso. A total of 104 samples were genetically characterized by direct sequencing of the p24 gag region and 80 were also subtyped in the V3–V5 env region. The genetic subtype distribution of the Congolese strains showed the predominance of subtype A (36.5% and 32.5% in gag and env, respectively) and G (30.8% and 21.25%), whereas subtype D strains represented 12.5% and 15%. Subtypes C, F, H, J, K and the CRFs-01, -02, -05 -06, and also the recently characterized CRF18 were seen at lower rates. Finally, 4.8% ( gag) and 6.25% ( env) of the strains could not be classified. Moreover, a high intra-subtype diversity was observed in our study. Among 70 strains which have been characterized in the two genomic regions, 14 (20%) appeared to be unique recombinants. These data show a high genetic variability in the Republic of Congo, where all the subtypes have been documented together with certain subsubtypes and several CRFs.

Genetic Variability ofgagandenvRegions of HIV Type 1 Strains Circulating in Slovenia

The aim of this study was to investigate the genetic diversity of HIV-1 strains circulating in Slovenia. Proviral DNA isolated from peripheral blood mononuclear cells (PBMCs) of 20 randomly selected HIV-1-infected individuals was classified into subtypes by sequence-based phylogenetic analysis of the env (C2V3) and gag (p24) regions of the viral genome. The phylogenetic tree based on env C2V3 sequences showed that 15 of the 20 samples were subtype B, two A1, one F1, one CRF01_AE, and one CRF02_AG. The phylogenetic analysis of the gag gene yielded identical results expect for one sample that had a discordant subtype; it was identified as subtype A1 in the env and AE in the gag region. Our study confirmed that although subtype B predominates, other subtypes and circulating recombinant forms (CRFs) are also present in Slovenia. The high intrasubtype genetic diversity of subtype B sequences suggests a multiple introduction of subtype B strains into Slovenia.

HIV-1 diversity and prevalence differ between urban and rural areas in the Mbeya region of Tanzania

To characterize HIV-1 strains in a potential vaccine trial cohort (CODE) in the Mbeya region of southwest Tanzania. Study volunteers (n = 3096) were recruited from urban areas in Mbeya Town, using two different recruitment strategies, and in a nearby rural village. Cryopreserved plasma from 507 HIV-1 prevalent cases was the source of viral RNA for HIV-1 genotyping by the Multi-region Hybridization Assay, the MHA(acd), and selected strains were confirmed by complete genome sequencing. The overall HIV-1 prevalence was 16.6% [95% confidence interval (CI), 15.3-17.9] within the cohort. HIV-1 prevalence was higher among women, and in urban areas. Recruitment through advertisement targeted a high-risk urban male population for HIV-1 infection [adjusted odds ratio (adj. OR), 1.68; 95% CI, 1.13-2.51] when compared with men recruited door-to-door. The complexity of the HIV-1 epidemic was also higher in urban areas evidenced by the high-risk of HIV-1 infection with a recombinant strain (adj. OR, 2.69; 95% CI, 1.08-6.69) and HIV-1 dual infection (adj. OR, 5.16; 95% CI, 1.07-24.9), mainly driven by urban men recruited through advertisement. Overall the urban epidemic was more genetically complex, with higher prevalence and more recombinants and dual infections. Vaccine trials in Mbeya region can assess a complex HIV-1 population dynamic and determine vaccine efficacy in relationship to the genetic diversity of HIV-1 strains that challenge vaccines.

High Genetic Diversity of HIV-1 Strains in Chad, West Central Africa

The genetic diversity of HIV-1 strains in Chad was documented with a total of 107 samples from patients attending the general hospital in N'Djamena, the capital city of Chad. The genetic subtypes were identified in the V3-V5 env and p24 gag regions by sequence and phylogenetic tree analyses. Of the 107 strains, 78 had the same subtype/CRF designation between env and gag. Four subtypes and three CRFs were found to cocirculate: subtype A, 20.5%; subtype D, 18.7%; CRF02_AG, 13.1%; CRF11_cpx, 13.1%; subtype G, 3.7%; CRF01_AE, 2.8%; and subtype F1, 0.9%. The remaining 29 strains (27%) had discordant subtypes or CRF designations between env and gag; in 15 of these 29 strains, a CRF was involved in the recombination event, and 10 were subtype G in gag and subtype A in env, forming a separate subcluster within subtypes G and A. Subtype D strains represent almost 20% of the HIV-1 strains circulating in Chad and form a separate subcluster in gag and env. Nearly full-length genome sequencing for two such strains (99TCD-MN011 and 99TCD-MN012) revealed that they represent nonrecombinant subtype D variants. Compared with neighboring countries, the genetic subtype distribution of HIV-1 strains in Chad is unique for several reasons: lower prevalence of CRF02, high prevalence of CRF11 and subtype D, and absence of CRF06. These data clearly show that subtype distribution is very heterogeneous in Africa, probably the result of different founder effects.

Spreading of HIV-1 subtype G and envB/gagG recombinant strains among injecting drug users in Lisbon, Portugal.

We have evaluated the genetic diversity of HIV-1 strains infecting injecting drug users (IDUs) in Lisbon, Portugal. Heteroduplex mobility assay and/or phylogenetic analysis revealed that env (C2V3C3 or gp41) subtype B is present in 63.7% of the 135 viral samples studied, followed by subtypes G (23.7%), A (6.7%), F (5.2%), and D (0.7%). Similar analysis of gag (p24/p7) performed on 91 of the specimens demonstrated that 49.5% of the infections were caused by subtype G viruses; other gag subtypes identified were B (39.5%), F (3.3%), A and D (1.1.% each), and the recombinant circulating form CRF02_AG (5.5%). Discordant env/gag sub-types were detected in 34.1% of the strains and may reflect the presence of dual infections and/or recombinant viruses. The presumptive B/G recombinant form was highly predominant (21 of 31). The genetic pattern of HIV-1 subtype B and G strains is suggestive of multiple introductions and recombination episodes and of a longstanding presence of both subtypes in the country. C2V3C3 amino acid sequences from IDU-derived subtype G viruses presented highly significant signatures, which distinguish the variants from this transmission group. The unusually high prevalence of subtype G sequences (34.1%), independent of the geographic origin of the infected individuals, makes this IDU HIV-1 epidemic unique.

Genetic subtypes of HIV type 1 viruses circulating in the Czech Republic.

We analyzed the genetic diversity of HIV-1 strains circulating in the Czech Republic. Phylogenetic analysis of the env and gag gene sequence fragments from 39 isolates revealed that the majority of these strains (32 of 39, 82%) were of subtype B; other genetic subtypes identified were A, C, F, and recombinant circulating form CRF01_AE. The isolates that did not cluster with subtype B originated almost exclusively from a heterosexual route of transmission. The molecular epidemiological data are suggestive of multiple entry of HIV-1 infection into the Czech Republic and show that the genetic pattern of the HIV-1 strains circulating in this country corresponds to that found in other European countries.

Diversity of the human immunodeficiency virus type 1 envelope glycoprotein in San Francisco Men's Health Study participants.

Multiple genetic subtypes of HIV-1, differing by up to 30% of nucleotides in their envelope coding sequences, have been identified in the global epidemic. In the United States, where HIV-1 infection with subtype B predominates, the interisolate diversity in envelope is 15% or more. It is recognized that geographic, temporal, and demographic variables can affect the genetic diversity of HIV-1 strains, but there have been few opportunities to evaluate these factors by population-based sampling. We have evaluated HIV-1 envelope diversity among participants in the San Francisco Men's Health Study (SFMHS), which represents a geographically, temporally, and demographically defined subset of HIV-1 infections in the United States. DNA was extracted from primary PBMCs obtained within 6 months of seroconversion and from individuals whose HIV-1 infection occurred between 1985 and 1989. The full-length envelope gene was PCR amplified, cloned, and sequenced from 17 different individuals. The sequences were compared within the cohort and with reference sequences from the United States and overseas, and their relationship to vaccine prototype strains LAI, MN, and SF2 was evaluated. SFMHS participants harbored HIV-1 subtype B infections with limited interpatient variation and a higher proportion of atypical V3 loop crown sequences than reference sequences of this subtype. Throughout gp160, the MN strain was less representative than LAI or SF2 among the patients examined. The geographic component of variation was apparently more substantial than the temporal, emphasizing the need for widely distributed geographic sampling in estimations of HIV diversity.