HIV type 1 genetic diversity and genotypic drug susceptibility in the Republic of Moldova

Identifying HIV-1 Transmission Clusters in Uzbekistan through Analysis of Molecular Surveillance Data

The CRF02_AG and sub-subtype A6 are currently the predominant HIV-1 variants in the Republic of Uzbekistan, but little is known about their time-spatial clustering patterns in high-risk populations. We have applied molecular evolution methods and network analyses to better understand the transmission patterns of these subtypes by analyzing 316 pol sequences obtained during the surveillance study of HIV drug resistance. Network analysis showed that about one third of the HIV infected persons were organized into clusters, including large clusters with more than 35 members. These clusters were composed mostly of injecting drug users and/or heterosexuals, with women having mainly high centrality within networks identified in both subtypes. Phylogenetic analyses of the 'Uzbek' sequences, including those publicly available, show that Russia and Ukraine played a role as the main sources of the current subtype A6 epidemic in the Republic. At the same time, Uzbekistan has been a local center of the CRF02_AG epidemic spread in the former USSR since the early 2000s. Both of these HIV-1 variants continue to spread in Uzbekistan, highlighting the importance of identifying transmission networks and transmission clusters to prevent further HIV spread, and the need for HIV prevention and education campaigns in high-risk groups.

Prevalence and spatiotemporal dynamics of HIV-1 Circulating Recombinant Form 03_AB (CRF03_AB) in the Former Soviet Union countries

Background

HIV-1 circulating recombinant forms (CRFs) infections has been increasing in Former Soviet Union (FSU) countries in the recent decade. One is the CRF03_AB, which circulated in the region since late 1990s and probably became widespread in northwestern FSU countries. However, there is not much information provided about the dissemination of this recombinant. Here, we examine the prevalence, evolutionary dynamics and dispersion pattern of HIV-1 CRF03_AB recombinant.

Methods

We analyzed 32 independent studies and 151 HIV-1 CRF03_AB pol sequences isolated from different FSU countries over a period of 22 years. Pooled prevalence was estimated using a random effects model. Bayesian coalescent-based method was used to estimate the evolutionary, phylogeographic and demographic parameters.

Results

Our meta-analysis showed that the pooled prevalence of CRF03_AB infection in northwestern FSU region was 5.9% [95%CI: 4.1–7.8]. Lithuania (11.6%), Russia (5.9%) and Belarus (2.9%) were the most affected by CRF03_AB. We found that early region wide spread of HIV-1 CRF03_AB originated from one viral clade that arose in the city of Kaliningrad in 1992 [95%HPD: 1990–1995]. Fourteen migration route of this variant were found. The city of Kaliningrad is involved in most of these, confirming its leading role in CRF03_AB spread within FSU. Demographic reconstruction point to this is that CRF03_AB clade seems to have experienced an exponential growth until the mid-2000s and a decrease in recent years.

Conclusion

These data provide new insights into the molecular epidemiology of CRF03_AB as well as contributing to the fundamental understanding of HIV epidemic in FSU.

Molecular Surveillance of HIV-1 Infection in Krasnoyarsk Region, Russia: Epidemiology, Phylodynamics and Phylogeography

BACKGROUND

The information about the dynamics of the viral population and migration events that affect the epidemic in different parts of the Russia is insufficient. Possibly, the huge size of the country and limited transport accessibility to certain territories may determine unique traits of the HIV-1 evolutionary history in different regions.

OBJECTIVE

The aim of this study was to explore the genetic diversity of HIV-1 in the Krasnoyarsk region and reconstruct spatial-temporal dynamics of the infection in the region.

METHODS

The demographic and virologic data from 281 HIV-infected individuals in Krasnoyarsk region collected during 2011-2016 were analyzed. The time to the most recent common ancestor, evolutionary rates, population growth, and ancestral geographic movements was estimated using Bayesian coalescent-based methods.

RESULTS

The study revealed moderate diversity of the HIV-1 subtypes found in the region, which included A6 (92.3%), CRF063_02A (4.3%), B (1.1%), and unique recombinants (2.5%). Phylogenetic reconstruction revealed that the A6 subtype was introduced into Krasnoyarsk region by one viral lineage, which arose around 1996.9 (1994.5-1999.5). The phylogeography analysis pointed to Krasnoyarsk city as the geographical center of the epidemic, which further spread to central neighboring districts of the region. At least two epidemic growth phases of subtype A6 were identified which included exponential growth in early-2000s followed by the decline in the mid/late 2010s.

CONCLUSION

This study demonstrates a change in the genetic diversity of HIV-1 in the Krasnoyarsk region. At the beginning of the epidemic, subtype A6 prevailed, subtypes B and CRF063_02A appeared in the region later.

Overview of HIV molecular epidemiology among people who inject drugs in Europe and Asia

HIV strains continuously evolve, tend to recombine, and new circulating variants are being discovered. Novel strains complicate efforts to develop a vaccine against HIV and may exhibit higher transmission efficiency and virulence, and elevated resistance to antiretroviral agents. The United Nations Joint Programme on HIV/AIDS (UNAIDS) set an ambitious goal to end HIV as a public health threat by 2030 through comprehensive strategies that include epidemiological input as the first step of the process. In this context, molecular epidemiology becomes invaluable as it captures trends in HIV evolution rates that shape epidemiological pictures across several geographical areas. This review briefly summarizes the molecular epidemiology of HIV among people who inject drugs (PWID) in Europe and Asia. Following high transmission rates of subtype G and CRF14_BG among PWID in Portugal and Spain, two European countries, Greece and Romania, experienced recent HIV outbreaks in PWID that consisted of multiple transmission clusters including subtypes B, A, F1, and recombinants CRF14_BG and CRF35_AD. The latter was first identified in Afghanistan. Russia, Ukraine, and other Former Soviet Union (FSU) states are still facing the devastating effects of epidemics in PWID produced by A_FSU (also known as IDU-A), B_FSU (known as IDU-B), and CRF03_AB. In Asia, CRF01_AE and subtype B (Western B and Thai B) travelled from PWID in Thailand to neighboring countries. Recombination hotspots in South China, Northern Myanmar, and Malaysia have been generating several intersubtype and inter-CRF recombinants (e.g. CRF07_BC, CRF08_BC, CRF33_01B etc.), increasing the complexity of HIV molecular patterns.

HIV-1 A1 Subtype Epidemic in Italy Originated from Africa and Eastern Europe and Shows a High Frequency of Transmission Chains Involving Intravenous Drug Users

Background

Subtype A accounts for only 12% of HIV-1 infections worldwide but predominates in Russia and Former Soviet Union countries of Eastern Europe. After an early propagation via heterosexual contacts, this variant spread explosively among intravenous drug users. A distinct A1 variant predominates in Greece and Albania, which penetrated directly from Africa. Clade A1 accounts for 12.5% of non-B subtypes in Italy, being the most frequent after F1 subtype.

Aim

Aim of this study was to investigate the circulation of A1 subtype in Italy and trace its origin and diffusion through phylogenetic and phylodynamic approaches.

Results

The phylogenetic analysis of 113 A1 pol sequences included in the Italian ARCA database, indicated that 71 patients (62.8%) clustered within 5 clades. A higher probability to be detected in clusters was found for patients from Eastern Europe and Italy (88.9% and 60.4%, respectively) compared to those from Africa (20%) (p < .001). Higher proportions of clustering sequences were found in intravenous drug users with respect to heterosexuals (85.7% vs. 59.3%, p = .056) and in women with respect to men (81.4% vs. 53.2%, p < .006). Subtype A1 dated phylogeny indicated an East African origin around 1961. Phylogeographical reconstruction highlighted 3 significant groups. One involved East European and some Italian variants, the second encompassed some Italian and African strains, the latter included the majority of viruses carried by African and Italian subjects and all viral sequences from Albania and Greece.

Conclusions

Subtype A1 originated in Central Africa and spread among East European countries in 1982. It entered Italy through three introduction events: directly from East Africa, from Albania and Greece, and from the area encompassing Moldavia and Ukraine. As in previously documented A1 epidemics of East European countries, HIV-1 A1 subtype spread in Italy in part through intravenous drug users. However, Eastern European women contributed to the penetration of such variant, probably through sex work.

Enhanced HIV-1 surveillance using molecular epidemiology to study and monitor HIV-1 outbreaks among intravenous drug users (IDUs) in Athens and Bucharest

BACKGROUND

A significant increase in HIV-1 diagnoses was reported among Injecting Drug Users (IDUs) in the Athens (17-fold) and Bucharest (9-fold) metropolitan areas starting 2011.

METHODS

Molecular analyses were conducted on HIV-1 sequences from IDUs comprising 51% and 20% of the diagnosed cases among IDUs during 2011-2013 for Greece and Romania, respectively. Phylodynamic analyses were performed using the newly developed birth-death serial skyline model which allows estimating of important epidemiological parameters, as implemented in BEAST programme.

RESULTS

Most infections (>90%) occurred within four and three IDU local transmission networks in Athens and Bucharest, respectively. For all Romanian clusters, the viral strains originated from local circulating strains, whereas in Athens, the local strains seeded only two of the four sub-outbreaks. Birth-death skyline plots suggest a more explosive nature for sub-outbreaks in Bucharest than in Athens. In Athens, two sub-outbreaks had been controlled (Re<1.0) by 2013 and two appeared to be endemic (Re∼1). In Bucharest one outbreak continued to expand (Re>1.0) and two had been controlled (Re<1.0). The lead times were shorter for the outbreak in Athens than in Bucharest.

CONCLUSIONS

Enhanced molecular surveillance proved useful to gain information about the origin, causal pathways, dispersal patterns and transmission dynamics of the outbreaks that can be useful in a public health setting.

Bayesian phylogeographic analyses clarify the origin of the HIV-1 subtype A variant circulating in former Soviet Union's countries

The HIV-1 subtype A variant dominating the HIV-1 epidemics in former Soviet Union (FSU) countries (A(FSU)) represents one of the major clades of the HIV-1 pandemic. This variant was reported to have begun spreading among injecting drug users (IDUs) in the Ukrainian city of Odessa in late 1994. Two competing hypotheses have been proposed on the ancestral origin of the A(FSU) variant, locating it either in the Democratic Republic of Congo (DRC) or in the Republic of Guinea (RG). The studies supporting these hypotheses employed phylogenetic analyses to identify HIV-1 sequences collected outside FSU countries ancestrally related to A(FSU). A different approach, based on Bayesian phylogenetic inference and coalescent-based population genetics, has been employed here to elucidate the ancestry of this HIV-1 variant and to improve our knowledge on its spread in FSU countries. The analyses were carried out using env (C2-V3-C3) and p24(gag) fragments of the HIV-1 genome. The inferred migration for the HIV-1 A(FSU) variant revealed only one significantly supported migration pathway from Africa to Eastern Europe, supporting the hypothesis of its origin in the DRC and estimating the upper limit of the migration of the ancestral virus from Africa around 1970. The support for an origin in the RG was negligible. The results supported the main role of Odessa as the epicenter of the A(FSU) epidemic, dating the tMRCA of the A(FSU) variant around 1984, ten years before its explosive expansion among IDUs. The estimated origin of the AFSU subcluster responsible for the IDU outbreak was also located in Odessa, with the estimated tMRCA around 1993. Statistically supported migration routes from Odessa to other cities of Ukraine, Russia, Kazakhstan, Uzbekistan and Belarus were also inferred by the Bayesian phylogeographic analysis. These results shed new light on the origin and spread of the HIV-1 A(FSU) variant.

Application of a new informatics tool for contamination screening in the HIV sequencing laboratory

BACKGROUND

Current HIV-1 sequencing-based methods for detecting drug resistance-associated mutations are open and susceptible to contamination. Informatic identification of clinical sequences that are nearly identical to one another may indicate specimen-to-specimen contamination or another laboratory-associated issue.

OBJECTIVES

To design an informatic tool to rapidly identify potential contamination in the clinical laboratory using sequence analysis and to establish reference ranges for sequence variation in the HIV-1 protease and reverse transcriptase regions among a U.S. patient population.

STUDY DESIGN

We developed an open-source tool named HIV Contamination Detection (HIVCD). HIVCD was utilized to make pairwise comparisons of nearly 8000 partial HIV-1 pol gene sequences from patients across the United States and to calculate percent identities (PIDs) for each pair. ROC analysis and standard deviations of PID data were used to determine reference ranges for between-patient and within-patient comparisons and to guide selection of a threshold for identifying abnormally high PID between two unrelated sequences.

RESULTS

The PID reference range for between-patient comparisons ranged from 83.8 to 95.7% while within-patient comparisons ranged from 96 to 100%. Interestingly, 48% of between-patient sequence pairs with a PID>96.5 were geographically related. The selected threshold for abnormally high PIDs was 96 (AUC=0.993, sensitivity=0.980, specificity=0.999). During routine use, HIVCD identified a specimen mix-up and the source of contamination of a negative control.

CONCLUSIONS

In our experience, HIVCD is easily incorporated into laboratory workflow, useful for identifying potential laboratory errors, and contributes to quality testing. This type of analysis should be incorporated into routine laboratory practice.

Distinct HIV type 1 strains in different risk groups and the absence of new infections by drug-resistant strains in Lithuania

To analyze HIV-1 genotypes in Lithuania and the transmission of drug-resistant viruses, HIV-1 sequences were obtained from 138 individuals, who were diagnosed as HIV-1 infected in 1990-2008 and represented all major risk groups. Subtype A strains, dominating in the former Soviet Union (90% of cases), were found in 60% of individuals, followed by subtype B (22%) and CRF03_AB (12%) strains. The remaining 7% of the strains included variants belonging to subtype C, CRF01_AE, CRF02_AG, more complex recombinant forms, and strains that could not be reliably genotyped. Analysis of virus genotypes per risk group revealed the circulation of distinct HIV-1 strains in different risk groups: subtype A viruses were present in 82% of injecting drug users (IDUs), but less than a half of heterosexually infected individuals and cases with unknown transmission route, and none of men having sex with men (MSM). We observed no mutations causing drug resistance among 27 newly diagnosed HIV-1 cases.

Detailed molecular epidemiologic characterization of HIV-1 infection in Bulgaria reveals broad diversity and evolving phylodynamics

Limited information is available to describe the molecular epidemiology of HIV-1 in Bulgaria. To better understand the genetic diversity and the epidemiologic dynamics of HIV-1 we analyzed 125 new polymerase (pol) sequences from Bulgarians diagnosed through 2009 and 77 pol sequences available from our previous study from persons infected prior to 2007. Epidemiologic and demographic information was obtained from each participant and phylogenetic analysis was used to infer HIV-1 evolutionary histories. 120 (59.5%) persons were infected with one of five different HIV-1 subtypes (A1, B, C, F1 and H) and 63 (31.2%) persons were infected with one of six different circulating recombinant forms (CRFs; 01_AE, 02_AG, 04_cpx, 05_DF, 14_BG, and 36_cpx). We also for the first time identified infection with two different clusters of unique A-like and F-like sub-subtype variants in 12 persons (5.9%) and seven unique recombinant forms (3.5%), including a novel J/C recombinant. While subtype B was the major genotype identified and was more prevalent in MSM and increased between 2000–2005, most non-B subtypes were present in persons ≥45 years old. CRF01_AE was the most common non-B subtype and was higher in women and IDUs relative to other risk groups combined. Our results show that HIV-1 infection in Bulgaria reflects the shifting distribution of genotypes coincident with the changing epidemiology of the HIV-1 epidemic among different risk groups. Our data support increased public health interventions targeting IDUs and MSM. Furthermore, the substantial and increasing HIV-1 genetic heterogeneity, combined with fluctuating infection dynamics, highlights the importance of sustained and expanded surveillance to prevent and control HIV-1 infection in Bulgaria.

Low prevalence of transmitted drug resistance among newly diagnosed HIV-1 patients in Latvia

Transmitted drug resistance (TDR) is a concern because it may reduce the efficacy of antiretroviral treatment. Plasma samples of 119 HIV-1-infected patients who were newly diagnosed at the Infectology Center of Latvia in 2005 and 2006 were analyzed by an in-house genotypic resistance assay to determine the prevalence of TDR in Latvia. TDR was identified using the WHO 2009 list of mutations for surveillance of TDR as implemented in the Stanford Calibrated Population Resistance tool. Neighbor-joining phylogenetic analyses were used to determine genetic subtype and investigate the relatedness of the sequences. Resistance testing was successful in 117 of 119 patients. The study population represented ∼20% of all patients that were diagnosed in Latvia in 2005 and 2006 and was well distributed between gender, transmission routes, and areas of residence. Four patients showed evidence of TDR, which represents a prevalence of TDR of 3.4% (95% CI: 0.9-8.5%). All four patients displayed single, but different resistance mutations (M46I, F53L, M41L, and G190A). All patients, except one, were predicted to respond well to standard first-line therapy in Latvia. The prevalence of TDR in Latvia was low, which partly may be due to the low proportion of HIV-1 patients who receive antiretroviral therapy. The results indicate that routine resistance testing in Latvia currently should be focused on patients who display treatment failure, rather than treatment naive patients.

Transmitted drug resistance in nonsubtype B HIV-1 infection

HIV-1 nonsubtype B variants account for the majority of HIV infections worldwide. Drug resistance in individuals who have never undergone antiretroviral therapy can lead to early failure and limited treatment options and, therefore, is an important concern. Evaluation of reported transmitted drug resistance (TDR) is challenging owing to varying definitions and study designs, and is further complicated by HIV-1 subtype diversity. In this article, we discuss the importance of various mutation lists for TDR definition, summarize TDR in nonsubtype B HIV-1 and highlight TDR reporting and interpreting challenges in the context of HIV-1 diversity. When examined carefully, TDR in HIV-1 non-B protease and reverse transcriptase is still relatively low in most regions. Whether it will increase with time and therapy access, as observed in subtype-B-predominant regions, remains to be determined.

Molecular epidemiology of HIV-1 in St Petersburg, Russia: predominance of subtype A, former Soviet Union variant, and identification of intrasubtype subclusters

OBJECTIVES

To examine HIV-1 genetic diversity in St. Petersburg.

METHODS

Partial HIV-1 pol sequences from 102 plasma samples collected in 2006 were analyzed with a Bayesian phylogeny inference method.

RESULTS

Subtype A, former Soviet Union (FSU) variant (AFSU), was the predominant clade (89.3%); other clades were subtypes B (9.7%) and F1 (1%). AFSU was predominant both among injecting drug users (98.2%) and heterosexually infected individuals (91.4%), whereas subtype B was more prevalent among homosexual men (75%). Within the AFSU variant, most sequences (93.5%) branched within 1 of 4 strongly supported subclusters. The largest comprised 63% AFSU viruses and was uncommon outside St Petersburg. A second subcluster (17.4% AFSU viruses) corresponds to the variant with the V77I substitution in protease, which is widely circulating in different FSU countries. Two minor subclusters comprised 8.7% and 6.5% AFSU viruses, respectively. There was no correlation between risk exposure and AFSU subclusters. Six of 8 subtype B sequences, 4 of them from homosexual men, grouped in a monophyletic subcluster.

CONCLUSIONS

The results of this study show a great predominance of AFSU viruses in St Petersburg and point to a few phylogenetically identifiable introductions as the origin of most current HIV-1 AFSU infections in the city.

Unequal evolutionary rates in the human immunodeficiency virus type 1 (HIV-1) pandemic: the evolutionary rate of HIV-1 slows down when the epidemic rate increases

HIV-1 sequences in intravenous drug user (IDU) networks are highly homogenous even after several years, while this is not observed in most sexual epidemics. To address this disparity, we examined the human immunodeficiency virus type 1 (HIV-1) evolutionary rate on the population level for IDU and heterosexual transmissions. All available HIV-1 env V3 sequences from IDU outbreaks and heterosexual epidemics with known sampling dates were collected from the Los Alamos HIV sequence database. Evolutionary rates were calculated using phylogenetic trees with a t test root optimization of dated samples. The evolutionary rate of HIV-1 subtype A1 was found to be 8.4 times lower in fast spread among IDUs in the former Soviet Union (FSU) than in slow spread among heterosexual individuals in Africa. Mixed epidemics (IDU and heterosexual) showed intermediate evolutionary rates, indicating a combination of fast- and slow-spread patterns. Hence, if transmissions occur repeatedly during the initial stage of host infection, before selective pressures of the immune system have much impact, the rate of HIV-1 evolution on the population level will decrease. Conversely, in slow spread, where HIV-1 evolves under the pressure of the immune system before a donor infects a recipient, the virus evolution at the population level will increase. Epidemiological modeling confirmed that the evolutionary rate of HIV-1 depends on the rate of spread and predicted that the HIV-1 evolutionary rate in a fast-spreading epidemic, e.g., for IDUs in the FSU, will increase as the population becomes saturated with infections and the virus starts to spread to other risk groups.

HIV epidemiology in the Northwestern Federal District of Russia: dominance of HIV type 1 subtype A

A rapidly advancing epidemic of HIV-1 infection has been documented among injecting drug users (IDUs) in Russia. The Northwestern Federal District was the first of the seven Russian Federal Districts involved in a drug-related HIV epidemic through an outbreak in Kaliningrad in 1996. The Northwestern Federal District has a high HIV prevalence rate having reached 252 per 100,000 by the end of 2003, exceeding the Russian average (180) by 1.4 times. The epidemic peaked in 2001. Since then the annual number of new cases has decreased, probably reflecting saturation among at least some IDU populations. However, at the same time, the heterosexual spread of HIV has become more prominent. To study the genetic epidemiology of HIV-1, samples were collected from 150 individuals covering a wide geographical area and different transmission groups in the Northwestern Federal District. Phylogenetic analysis revealed that an Eastern European subtype A HIV-1 strain similar to those reported earlier among IDUs in other regions of Russia accounted for 80% of HIV-1 infections and was the predominant subtype in six out of seven administrative territories studied both among IDUs and heterosexually infected persons. As an exception to the dominant role of the Eastern European subtype A strain, the CRF03-AB strain was found to be dominant in the city of Cherepovets located in the north central European Russian territory of Vologda Oblast. This is the first report of the CRF03-AB strain causing an outbreak outside the Kaliningrad region.

Molecular epidemiology of HIV Type 1 in Ukraine: birthplace of an epidemic

During the 1990s, HIV-1 spread rapidly through drug networks in Ukraine and from there throughout the former Soviet Union. To examine the origins of this epidemic, the genetics of HIV-1 in Ukraine were studied. Proviral DNA from PBMC was extracted and PCR amplified. Part of pol and nearly full genomes of HIV-1 were sequenced and characterized. The predominant genetic form in 163 strains was subtype A (66%), followed by subtypes B (30%), C (2%), D (1%), and a new AB recombinant form (1%). HIV strains from Kiev were diverse having subtypes A, B, C, and D. In Crimea, Donetsk, Poltava, and Odessa, however, the strains were overwhelmingly subtype A, while in Nikolaev subtype B predominated. After the near simultaneous introduction of subtypes A and B in Ukraine, subtype B remained where it was introduced while subtype A spread widely, creating the fastest growing epidemic in the world.

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.

The HIV type 1 epidemic in Belarus: predominance of Eastern European subtype A strains and circulation of subtype B viruses

To study the molecular epidemiology of HIV-1 in Belarus, where the rapid spread of HIV-1 has been registered since 1996, we obtained HIV-1 sequences from 30 individuals living in five cities in both the main geographic areas of the epidemic (Gomel and Minsk regions) and territories where spreading of the epidemic remains limited (Grodno region). Analysis of env V3 and gag p17/p24 sequences demonstrated that infections in all 12 injecting drug users and 14 of 18 individuals infected through sexual contacts were caused by subtype A viruses that are specific for the epidemic in the former Soviet Union (IDU-A viruses), while the remaining four infections were caused by phylogenetically unrelated to each other subtype B viruses. Extrapolation of these results to the total population of HIV-1-infected individuals in Belarus allowed us to estimate that IDU-A viruses account for nearly 95% of HIV-1 infections in Belarus.

Diversity of human immunodeficiency virus type 1 subtype A and CRF03_AB protease in Eastern Europe: selection of the V77I variant and its rapid spread in injecting drug user populations

To characterize polymorphisms of the subtype A protease in the former Soviet Union, proviral DNA samples were obtained, with informed consent, from 119 human immunodeficiency virus type 1 (HIV-1)-positive untreated injecting drug users (IDUs) from 16 regions. All individuals studied have never been treated with antiretroviral drugs. The isolates were defined as IDU-A (n = 115) and CRF03_AB (n = 4) by using gag/env HMA/sequencing. The pro region was analyzed by using sequencing and original HIV-ProteaseChip hybridization technology. The mean of pairwise nucleotide distance between 27 pro sequences (23 IDU-A and 4 CRF03_AB) was low (1.38 +/- 0.79; range, 0.00 to 3.23). All sequences contained no primary resistance mutations. However, 13 of 23 (56.5%) subtype A isolates bore the V77I substitution known as the secondary protease mutation. V77I was associated with two synonymous substitutions in triplets 31 and 78, suggesting that all V77I-bearing viruses evolved from a single source in 1997. Hybridization analysis showed that 55 of 115 (47.8%) HIV-1 isolates contained V77I, but this variant was not found in any of 31 DNA samples taken from regions, where the HIV-1 epidemic among IDUs started earlier 1997, as well as in any of four CRF03_AB isolates. The results of analysis of 12 additional samples derived from epidemiologically linked subjects showed that in all four epidemiological clusters the genotype of the donor and the recipients was the same irrespective of the route of transmission. This finding demonstrates the transmission of the V77I mutant variant, which is spreading rapidly within the circulating viral pool in Russia and Kazakhstan. The continued molecular epidemiological and virological monitoring of HIV-1 worldwide thus remains of great importance.

Temporal trends in the HIV-1 epidemic in Russia: predominance of subtype A

During the period 1996-1997, three highly homogeneous variants of HIV-1 were identified, circulating among injecting drug users (IDUs) in the former Soviet Union republics. One of these belonged to HIV-1 genetic subtype A (IDU-A), another belonged to HIV-1 genetic subtype B (IDU-B) and the third was a recombinant between the first two variants (CRF03_AB). However, since 1997, the HIV-1 epidemic has affected an increasing number of geographic regions in Russia. This study was undertaken to survey the prevailing genetic variants and to estimate the current proportions of these three HIV-1 genetic subtypes in Russia. Blood samples were taken in 1999-2003 from 1090 HIV-infected individuals and analysed by gag/env HMA. The IDU-A variant was found to be the majority variant (89.7-100%) in 44 of 45 regions of the Russian Federation studied. The IDU-A variant was also found to spreading rapidly through heterosexual transmission in 1999-2003 (30/34, 88%). CRF03_AB predominates in the Kaliningrad region only (28/29, 96.6%). The IDU-B variant is currently of minor importance in the IDU epidemic but other European subtype B variants predominate among men having sex with men (18/18, 100%). Sequence analysis of the env V3 encoding regions derived from HIV-1 infected individuals in Yekaterinburg (the main centre of the HIV-1 epidemic in Russia in 2002-2003) showed that the IDU-A variant is still highly homogeneous. The mean pairwise nucleotide distance (n = 9) was 2.89 +/- 1.14 (range 1.36-6.14). However, the mean genetic distance between each sequence within the samples collected from the Yekaterinburg IDU-A variant subset and the IDU-A consensus is 2.51 +/- 1.06 (range 1.36-4.66) and considerably higher than in South Russia in 1996 (0.79 +/- 0.51, range 0.38-1.90). The current HIV-1 epidemic in Russia is almost entirely caused by a highly homogeneous A-subtype strain, which will influence vaccine development strategies and must be taken into account in the quality control of molecular tests for the diagnosis of HIV-1.

An HIV type 1 subtype A outbreak among injecting drug users in Kazakhstan

Kazakhstan experienced the start of the HIV-1 outbreak among intravenous drug users (IDUs) in 1997. To characterize genetically HIV-1 strains circulating in this country, peripheral blood mononuclear cells (PBMCs) DNA samples (1999-2002) derived from HIV-infected IDUs and their sexual partners in Pavlodar (n = 19), Shymkent (n = 6), and Qaraghandy (n = 18) regions were analyzed by the gag/env heteroduplex mobility assay (HMA). The 366-bp proviral env gene fragments encoding the gp120 C2-V3 region obtained from 16 individuals were sequenced. The results of HMA revealed that all 43 HIV-1 strains studied belonged to gag/env subtype A. The nucleotide sequence analysis showed a marked genetic homogeneity with the mean genetic distance being 3.63 +/- 2.39 (range 0.00-12.13). The mean genetic distance between each sequence within the Kazakhstan set and the East-European IDU subtype A consensus was 2.94 +/- 1.92 (range 0.79-8.48). The data presented thus confirm the spreading of the same IDU subtype A virus in the former Soviet Union.

Molecular cloning and analysis of full-length genome of HIV type 1 strains prevalent in countries of the former Soviet Union

The HIV-1 epidemic among injecting drug users (IDUs) in countries of the former Soviet Union (FSU) was caused mainly by two HIV-1 variants: subtype A and CRF03-AB. To date only three full-length HIV-I genomes from the FSU have been sequenced: one subtype A from Byelorussia and two CRF03-AB from Russia. We report the full-length genome cloning and analysis of two more HIV-1 strains from the FSU countries (98UA0116 of subtype A and 98BY10443 of CRF03-AB). Isolate 98UA0116 is the second cloned and sequenced full-length HIV-1 genome of subtype A lineage from the FSU, which may be a novel subsubtype within sub-type A. Isolate 98BY10443 is the third full-length HIV-1 genome of CRF03-AB in the world to be cloned and sequenced. Additionally, it is the first CRF03-AB strain discovered in Byelorussia. Cloned genomic sequences of the FSU HIV-1 isolates are being used for the development of a region-specific HIV-1 vaccine.

Analysis of partial pol and env sequences indicates a high prevalence of HIV type 1 recombinant strains circulating in Gabon

Forty-one HIV-1 strains from Gabonese patients were studied according to the following strategy: nested polymerase chain reaction were performed to obtain an approximately 1,100-bp fragment containing the protease gene and the 5' half of the reverse transcriptase gene. Additional amplifications were carried out to obtain an approximately 700-bp fragment encompassing the C2V3 env gene. Fragments of 600 to 1,200 bp in the gag gene overlapping the pol sequences were used for the study of recombination patterns. Phylogenetic analyses of the different fragments were used to investigate HIV-1 diversity in Gabon. Thirty-one strains were sequenced in the env and pol genes and phylogenetic analyses classified them as subtype A (n = 2), D (n = 4), G (n = 1), H (n = 1), CRF02 (n = 8), and CRF MAL-like (n = 6); in addition, there were 6 unique recombinant forms and 1 unclassified strain, and in 2 cases pol/env sequences classified strains as subtype D whereas gag phylogeny classified them as subtype A. In 10 cases only 1 fragment was available: 4 env (2 subtype D, 1 subtype H, and 1 subtype U) and 6 pol (1 subtype A, 1 subtype C, 2 subtype G, and 2 subtype U). Minor mutations associated with viral resistance to antiretroviral drugs were observed in more than 80% of analyzed strains. Our study confirms the extensive HIV-1 diversity found in Central Africa, with more than 70% of strains from Gabon exhibiting discordant clustering in pol and env genomic regions and less than 60% concordance between sequencing and heteroduplex mobility assay genotyping. These findings highlight the fact that Central Africa represents the epicenter for the origin of HIV-1. The strategy of sequencing pol in association with env has proved to be useful for analysis of the recombinant strains. The main advantage of this approach is that it also allows for evaluation of genotypic susceptibility to antiretroviral drugs without the need for supplementary analyses.