Correlation of genetic and serologic approaches to HIV-1 subtyping in Thailand

An effective tool for identifying HIV-1 subtypes B, C, CRF01_AE, their recombinant forms, and dual infections in Southeast Asia by the multi-region subtype specific PCR (MSSP) assay

The RV144 Thai vaccine trial has been the only vaccine study to show efficacy in preventing HIV infection. Ongoing molecular surveillance of HIV-1 in Southeast Asia is vital for vaccine development and evaluation. In this study a novel tool, the multi-region subtype specific PCR (MSSP) assay, that was able to identify subtypes B, C, CRF01_AE for Thailand, other Southeast Asian countries, India and China is described. The MSSP assay is based on a nested PCR strategy and amplifies eight short regions distributed along the HIV-1 genome using subtype-specific primers. A panel of 41 clinical DNA samples obtained primarily from opiate users in northern Thailand was used to test the assay performance. The MSSP assay provided 73-100% sensitivity and 100% specificity for the three subtypes in each genome region. The assay was then field-tested on 337 sera from HIV infected northern Thai drug users collected between 1999 and 2002. Subtype distribution was CRF01_AE 77.4% (n=261), subtype B 3.3% (n=11), CRF01_AE/B recombinant 12.2% (n=41), CRF01_AE/C recombinant 0.6% (n=2), and non-typeable 6.5% (n=22). The MSSP assay is a simple, cost-effective, and accurate genotyping tool for laboratory settings with limited resources and is sensitive enough to capture the recombinant genomes and dual infections.

Inferring viral population structures using heteroduplex mobility and DNA sequence analyses

Heteroduplex mobility (HMA) and tracking assays (HTA) are used to assess genetic relationships between DNA molecules. While distinguishing relationships between clonal or nearly clonal molecules is relatively straightforward, inferring population structures is more complex. To address this issue, HIV-1 quasispecies with varying levels of diversity were studied using both HTA and DNA sequencing. Viral diversity estimates and the temporal features of virus evolution were found to be generally concordant between HTA and DNA sequencing. In addition, the distribution of pairwise differences and the rates of virus divergence were similar between the two methods. These findings support the use of HTA to characterize variant populations of DNA and strengthen previous inferences concerning the evolution of HIV-1 over the course of infection.

Rapid identification of human immunodeficiency virus type 1 CRF01_AE and BC recombinants by subtype-specific PCR

A subtype-specific PCR approach is described for the identification of HIV-1 intersubtype CRF01_AE and BC recombinants, the two predominant subtypes in Southern China. Primers were designed based on the env and gag regions of the HIV-1 genome. Nested PCRs with primers targeting the env region were performed to amplify subtype C, CRF01_AE, or BC recombinants. To differentiate BC recombinants from subtype C virus, a BC recombinant specific gag PCR was then performed. In order to identify the CRF07_BC and CRF08_BC recombinant forms, an additional PCR step was included. Four HIV-1 samples of known subtype, 77 samples with unknown-subtype, and 30 HIV-negative control samples were tested by the new assay. The results of this PCR-based subtyping approach were compared with that of a sequence-based phylogenetic analysis. In total, 73 (94.8%) samples were amplified by the subtype-specific PCR reactions, of which 39 were identified as CRF01_AE, 14 as CRF07_BC, and 20 as CRF08_BC. The sensitivity of this assay was 90.7% for the CRF01_AE recombinant and 100% for BC recombinants. The specificity was 100% when used to identify 30 HIV-negative samples. The reproducibility was 93.8% for CRF01_AE, and 100% for BC recombinants. This subtype-specific PCR technique represents a simple, rapid, and low-cost assay for the identification of HIV-1 CRF01_AE and BC recombinants in Southern China.

Expression of monocyte markers in HIV-1 infected individuals with or without HIV associated dementia and normal controls in Bangkok Thailand

HIV Associated Dementia (HAD) is a complication of HIV infection in developed countries and is still poorly defined in resource-limited settings. In this study we investigated the expression of the monocyte phenotype CD14CD16HLADR and the inflammatory profiles in monocytes supernatants by surface-enhanced laser desorption/ionization-time of flight (SELDI-TOF) mass spectrometry in a cohort of HAD and non-HAD Thai volunteers prior to the initiation of ARV. The CD14CD16HLADR phenotype was significantly increased in monocytes from HAD and non-HAD versus negative controls, but there was no difference in phenotype and in the secretion protein profiles between the two seropositive groups. In addition, monocytes supernatants from HAD and non-HAD did not induced apoptosis or cell death in brain aggregate culture. In conclusion it appears that HAD in Thai individuals has a different immunological profile then in North America cohorts.

Identifying HIV-1 dual infections

Transmission of human immunodeficiency virus (HIV) is no exception to the phenomenon that a second, productive infection with another strain of the same virus is feasible. Experiments with RNA viruses have suggested that both coinfections (simultaneous infection with two strains of a virus) and superinfections (second infection after a specific immune response to the first infecting strain has developed) can result in increased fitness of the viral population. Concerns about dual infections with HIV are increasing. First, the frequent detection of superinfections seems to indicate that it will be difficult to develop a prophylactic vaccine. Second, HIV-1 superinfections have been associated with accelerated disease progression, although this is not true for all persons. In fact, superinfections have even been detected in persons controlling their HIV infections without antiretroviral therapy. Third, dual infections can give rise to recombinant viruses, which are increasingly found in the HIV-1 epidemic. Recombinants could have increased fitness over the parental strains, as in vitro models suggest, and could exhibit increased pathogenicity. Multiple drug resistant (MDR) strains could recombine to produce a pan-resistant, transmittable virus.

We will describe in this review what is presently known about super- and re-infection among ambient viral infections, as well as the first cases of HIV-1 superinfection, including HIV-1 triple infections. The clinical implications, the impact of the immune system, and the effect of anti-retroviral therapy will be covered, as will as the timing of HIV superinfection. The methods used to detect HIV-1 dual infections will be discussed in detail. To increase the likelihood of detecting a dual HIV-1 infection, pre-selection of patients can be done by serotyping, heteroduplex mobility assays (HMA), counting the degenerate base codes in the HIV-1 genotyping sequence, or surveying unexpected increases in the viral load during follow-up. The actual demonstration of dual infections involves a great deal of additional research to completely characterize the patient's viral quasispecies. The identification of a source partner would of course confirm the authenticity of the second infection.

HIV DNA and dementia in treatment-naïve HIV-1-infected individuals in Bangkok, Thailand

High HIV-1 DNA (HIV DNA) levels in peripheral blood mononuclear cells (PBMC) correlate with HIV-1-associated dementia (HAD) in patients on highly active antiretroviral therapy (HAART). If this relationship also exists among HAART-naïve patients, then HIV DNA may be implicated in the pathogenesis of HAD. In this study, we evaluated the relationship between HIV DNA and cognition in subjects naïve to HAART in a neuro AIDS cohort in Bangkok, Thailand. Subjects with and without HAD were recruited and matched for age, gender, education, and CD4 cell count. PBMC and cellular subsets were analyzed for HIV DNA using real-time PCR. The median log(10) HIV DNA copies per 10(6) PBMC for subjects with HAD (n=15) was 4.27, which was higher than that found in subjects without dementia (ND; n=15), 2.28, p<0.001. This finding was unchanged in a multivariate model adjusting for plasma HIV-1 RNA levels. From a small subset of individuals, in which adequate number of cells were available, more HIV DNA was in monocytes/macrophages from those with HAD compared to those with ND. These results are consistent with a previous report among HAART-experienced subjects, thus further implicating HIV DNA in the pathogenesis of HAD.

Determination of HIV-1 subtypes (A-D, F, G, CRF01_AE) by PCR in the transmembrane region (gp41) with novel primers

HIV-1 has a huge genetic diversity. So far, nine subtypes have been isolated, namely, subtypes A, B, C, D, F, G, H, J, and K. Epidemiological study provides information which may help in the development of HIV-1 prevention programs or health policies. In the future, subtyping may also be critical for vaccine development, and an effective anti-viral drug will need to be effective for different subtypes of HIV virus. The analysis of the nucleotide sequence of the v3 region is considered the most reliable method for determining the HIV-1 subtype. However, the procedures for determining the v3 sequences are complicated and time consuming, requiring expensive reagents, equipment, and well-trained personnel. The polymerase chain reaction (PCR) method using subtype-specific primers for HIV-1 subtyping is easier and faster. The objective of this study was to develop subtype-specific primers for subtyping PCR. The specific primers were designed for subtypes A, B, C, D, F, G, and CRF01_AE, and these primers could be applied to assay for various HIV-1 subtypes in the clinical samples. The specific primers were designed for each subtypes in the gp41 region. The result of PCR was compared with the subtypes which was determined by the v3 sequence. The results of subtyping by PCR using the newly designed primers could detect 29 of 33 patients tested, and all matched those obtained by nucleotide sequencing of the env v3 region except for three subjects, which were differentiated as CRF02_AG. The newly designed primers functioned accurately and conclusively. In comparison with PCR as a method for the determination of subtypes, sequence analysis requires better-trained personnel, more expensive reagents, and more equipment and time.

A new circulating recombinant form, CRF15_01B, reinforces the linkage between IDU and heterosexual epidemics in Thailand

HIV-1 subtype B and CRF01_AE have been in circulation in Thailand and Southeast Asia for more than a decade. Initially separated by risk group, the two strains are increasingly intermixed, and two recombinant strains of essentially reciprocal structure have been recently reported. Here we identify additional CRF_01B recombinants and provide the evidence that HIV-1 strains now pass freely between the two high-risk populations. HIV isolates that showed discordance between CRF01_AE and subtype B in multi-region genotyping assays were selected for the study. They were drawn from 3 different cohorts in Thailand representing different risk behaviors and demographic characteristics: a drug user cohort in the north, a family planning clinic attendee cohort in the southeast, and a cohort study of the mucosal virology and immunology of HIV-1 infection in Thailand. The DNA from these isolates was PCR amplified to recover the full HIV-1 genome and subjected to sequencing and phylogenetic analysis. We establish that one particular CRF_01B recombinant, with the external envelope of subtype B and the rest of the genome from CRF01_AE, is circulating widely in Thailand. Termed CRF15_01B (also referred to as CRF15), the strain was primarily heterosexually transmitted, although injecting drug use (IDU) also played a role. In aggregate data from the studies, CRF15 constituted 1.7% of all HIV-1 infections (95% confidence interval 0.5-4.4%) and was dispersed widely in the country. The previously separate heterosexual and IDU epidemics have apparently been bridged by a new CRF. The entry of CRF15 into the mainstream of the epidemic signals new complexity in the long stable molecular picture in Thailand. These recombinants must be considered in ongoing or projected efficacy evaluations of HIV-1 vaccines and antiviral therapies.

Development and evaluation of a DNA enzyme immunoassay method for env genotyping of subtypes A through G of human immunodeficiency virus type 1 group M, with discrimination of the circulating recombinant forms CRF01_AE and CRF02_AG

The tools currently available for genetic subtyping of human immunodeficiency virus type 1 are laborious or can be used only for the analysis of a limited number of samples and/or subtypes. We developed and evaluated a molecular biology-based method using subtype-specific oligonucleotide probes for env genotyping of subtypes A through G, CRF01_AE, and CRF02_AG. DNA enzyme immunoassay (DEIA) genotyping is based on nested PCR amplification of the 5' end of the env gene (proviral DNA), followed by subtype-specific hybridization and immunoenzymatic detection on microplates. DEIA genotyping was validated with a large number of samples (n = 128) collected in Europe (France; n = 47), West-Central Africa (Cameroon; n = 36), and West Africa (Senegal; n = 45). Three different formats, depending on the distribution of subtypes in the three countries, were developed. The results were compared with those obtained by sequencing of the V3-V5 region and phylogenetic analysis or an env heteroduplex mobility assay. Additional sequencing and phylogenetic analyses of the DEIA region (the first codon of the env coding sequence to the middle of conserved region C1 of gp120) were performed to investigate the reasons for discrepancies. Intense and highly specific reactions between the oligonucleotide probes and the corresponding samples were observed. Overall, correct identification was achieved for 107 of 128 samples (83.6%). One sample was not amplified, 10 (8%) were nontypeable (NT), and 10 (8%) were misidentified. Six of the 10 discordant samples were further investigated by phylogenetic analysis, which indicated that these samples corresponded to recombinants involving the env 5' end and the V3 and V5 regions of the two parental clades. Sequencing of NT samples showed numerous differences between sample and probe sequences, resulting in a lack of hybridization, and revealed the limitations of the selected probes in terms of specificity and sensitivity. We demonstrated the feasibility of DEIA genotyping: six subtypes plus the two most prevalent circulating recombinant forms were discriminated by using the 5' end of the env gene. This method can be adapted to the local situation by including only probes that correspond to the prevalent strains.

Differentiation of subtypes B and E of human immunodeficiency virus type 1 by polymerase chain reaction using novel env gene primers

Novel sets of env gene PCR primers for distinguishing human immunodeficiency virus type 1 (HIV-1) subtypes B and E were designed. These primers anneal to different regions of the env gene and amplify DNA fragments of distinct sizes in a subtype-specific manner. Blood samples from 11 HIV-1 carriers in Thailand and 46 carriers in Japan were examined by PCR. The new env primers detected HIV-1 proviral DNA in 100% (11/11) and 88% (37/42) of the subtype B and E infection cases, respectively. The env primers also detected proviral DNA in saliva and breast milk samples in seven of 11 cases and two of three cases, respectively. The PCR subtyping results matched completely with those obtained by nucleotide sequencing of the env V3 region. The results suggest that the PCR using the env primers designed in this study may be an accurate and cost-effective method for differentiating subtypes B and E of HIV-1 in a large number of clinical samples. However, subtype E specific primer cross-react with subtype A, C, G, the new primer in this study is useful for regions in South East Asia where subtype E is predominant.

HIV type 1 non-B subtype prevalence in Spain, 1997-1998

We have evaluated the prevalence of HIV-1 non-B subtypes in Spain by means of an enzyme immunoassay (EIA) for discrimination between B and non-B subtypes. Samples were obtained from newly diagnosed patients attended at internal medicine outpatient clinics between October 1997 and October 1998. Discrimination between HIV-1 B and non-B subtypes was carried out by means of the EIA, with V3 synthetic peptides specific to the different subtypes. Non-B-serotyped samples were genetically analyzed in the gp41 region from the original sera. During the study period, 909 samples were collected from 21 medical units located in various Spanish geographical regions. Serotyping was possible in 885 cases, of which 791 were assigned as B serotype (89.38%), 70 showed no reactivity to any of the peptides (7.91%), and the remaining samples displayed other reaction patterns (2.72%). Of the 94 non-B-assigned samples, 65 were genetically characterized in the gp41 region of the env gene: 55 were B subtype, 5 were A subtype (4 clustered with CRF02AG reference strains), 3 were C subtype, and 2 were G subtype. The prevalence rate for non-B subtypes in Spain was established at 1.13% (95% CI, 0.59-2.21). Although the B subtype is predominant in the Spanish population, other subtypes have been detected.

Genetic diversity and phylogenetic analysis of human immunodeficiency virus type 1 subtypes circulating in French Guiana

We investigated the characterization of different HIV-1 subtypes present in French Guiana by use of three different methods. Serological methods were used for the initial screening, which were then confirmed by the heteroduplex mobility assay (HMA). The V3 env region was subsequently sequenced for phylogenetic analysis, to confirm the subtype of the samples, and to assign a subtype to samples that gave results that were difficult to interpret or discordant by serology or HMA. A total of 221 HIV-1 seropositive samples were typed; 110 of them were confirmed by HMA and 16 were sequenced. Of the 221 samples tested 210 patients (95%) were found to be infected with subtype B, 10 (4.5%) were infected with subtype A, and one patient was infected with subtype F. Phylogenetic analysis demonstrated that the strains from French Guiana were closely related to the subtype A and B subtypes, and that one strain was closely related to an F subtype (100% bootstrap value). Four strains from French Guiana clustered in the subtype A (99% bootstrap value) and the other strains were associated with subtype B (100% bootstrap value). The geographic position of French Guiana suggested that HIV-1 was probably introduced into the country via several routes, and thus the pattern of the HIV-1 epidemic might evolve in the near future.

Temporal trends and molecular epidemiology of HIV-1 infection in Taiwan from 1988 to 1998

Eight hundred and seventy-nine HIV-1-infected patients (comprising 46% of reported HIV-1/AIDS cases in Taiwan) were recruited for this study of the molecular epidemiology of HIV-1 in Taiwan from 1988 to 1998. HIV-1 subtypes were determined using a modified peptide-enzyme immunoassay complemented with DNA sequencing and phylogenetic analysis. Of the 807 HIV-1 infected men, 68.2% were infected with HIV-1B, 29.5% with HIV-1 circulating recombinant form (CRF)01_AE and 2.3% with other subtypes. Of the 72 HIV-1-infected women, 72.2% were infected with HIV-1 CRF01_AE, 13.9% with HIV-1B, and 13.9% with other subtypes. All of 8 foreign-born, Southeast Asian women and 6 of 7 (85.7%) Taiwan-native female commercial sex workers were infected with HIV-1 CRF01_AE. Fourteen of the 33 (42.4%) heterosexual married men with CRF01_AE had transmitted HIV-1 to their wives, whereas only 1 of 17 (5.9%) men with HIV-1 B had transmitted HIV-1 to their spouses (p < .01). Of 18 heterosexual male injecting drug users, 1 of 12 (8.5%) with HIV-1B and 5 of 6 (83.3%) with HIV-1 CRF01_AE had had sexual contact with female commercial sex workers (p < .01). Therefore, in this population, CRF01_AE was preferentially associated with heterosexual risk groups, a finding compatible with differences in transmission capability between B and non-B subtypes.

HIV type 1 subtype E-infected patients with broadened, dual (B/E) V3 loop serology have increased cross-neutralizing antibodies

The two prevalent subtypes of HIV-1 circulating in Thailand are subtypes E and B. While the most prevalent subtype continues to be E using molecular typing assays, immunologically, a subset of subtype E-infected patients (3.4% in 1997) have binding antibodies to both the E and B V3 loops in a peptide ELISA. To assess the potential function of this dual (B/E) V3 reactivity, plasmas from patients with genetically defined HIV-1 subtype E infection and either E or B/E V3 serotypes were compared for magnitude and breadth of neutralization of seven primary and laboratory-adapted subtype B and E viruses. Dually reactive (B/E) plasmas showed significantly increased cross-neutralizing activity against subtype B viruses (p < 0.001), and increased neutralization of the panel of viruses overall (p < 0.02), as compared to monoreactive E serotype plasmas. While the total envelope binding antibody titers to both subtype B and E envelopes did not differ significantly between the E and B/E plasmas, 67% of B/E plasmas neutralized >50% of the viruses in the panel, and only 14% of E plasmas showed this broadened neutralizing activity. These data suggest that dual (B/E) V3 loop reactivity may be a marker of broader immune recognition of HIV envelope epitopes in subtype E-infected patients. V3 loop antibody, perhaps in conjunction with antibodies to additional epitopes, may play a role in neutralization of virus isolates from Thailand.

Serological approaches to subtyping of HIV-1 in injecting drug users in Russia: evidence of subtype homogeneity at the main sites of the epidemic

The aim of this study was to develop and evaluate a simple V3 peptide-based enzyme immunoassay (PEIA) for large-scale serotyping of HIV-1 specimens derived from injecting drug users (IDUs) in the Russian Federation. Two synthetic peptides were evaluated, named P1 (RKSIHIGPGRAFYATGD) and P2 (RTSVRIGPGQVFYKTGD), in an PEIA on 63 HIV-1 IDUs sera for which genotypes had been determined by heteroduplex mobility assay (HMA) and sequencing. The sensitivities of P1 (subtype B) and P2 (subtype A) were 87% and 75% respectively. Specificity of the assay was 100% for both peptides, with 100% predictive values of a monoreactive positive test for both peptides. Using the PEIA with peptides P1 and P2, we have serotyped 375 of 477 serum samples derived from IDUs in 4 main sites of the HIV-1 epidemic in Russia. The results demonstrated a high level of subtype homogeneity in all regions studied. In 3 of 4 territories, Tver' (n=345), and Rostov-on-Don (n=61) regions, and Krasnodar Kray (n=27), 100% of typable sera were found to belong to env subtype A. On the other hand, all specimens serotyped in the Kaliningrad region (n=38) belonged to env subtype B, and there is strong evidence that the recombinant gagAenvB virus which has caused the largest outbreak of HIV-1 in Russia is located in this region. At the present time another parental strain with gagBenvB genotype is of minor importance in the IDUs HIV-1 epidemic in Russia.

Characterization of a virtually full-length human immunodeficiency virus type 1 genome of a prevalent intersubtype (C/B') recombinant strain in China

A molecular epidemiology study was conducted among more than 100 human immunodeficiency virus type 1 (HIV-1) subtype C seropositive intravenous drug users (IDUs) from China. Genotyping based on the envelope C2V3 coding region revealed the highest homology of the most prevalent virus strains circulating throughout China to subtype C sequences of Indian origin. Based on these results, a virtually full-length genome representing the most prevalent class of clade C strains circulating throughout China was directly amplified from peripheral blood mononuclear cells of a selected HIV-infected IDU and subcloned. Sequence analysis identified a mosaic structure, suggesting extensive intersubtype recombination events between genomes of the prevalent clade C and (B')-subtype Thai virus strains of that geographic region. Recombinant Identification Program analysis and phylogenetic bootstrapping suggested that there were 10 breakpoints (i) in the gag-pol coding region, (ii) in vpr and at the 3' end of the vpu gene, and (iii) in the nef open reading frame. (B')-sequences therefore include (i) several insertions in the gag-pol coding region; (ii) 3'-vpr, the complete vpu gene, and the first exons of tat and rev; and (iii) the 5' half of the nef gene. Breakpoints located in the vpr/vpu coding region as well as in the nef gene of 97cn54 were found at almost identical positions of all subtype C strains isolated from IDUs living in different areas of China, suggesting a common ancestor for the C/B' recombinant strains. More than 50% of well-defined subtype B-derived cytotoxic T-lymphocyte epitopes within Gag and Pol and 10% of the known epitopes in Env were found to exactly match sequences within in this clade C/B' chimeric reference strain. These results may substantially facilitate a biological comparison of clade C-derived reference strains as well as the generation of useful reagents supporting vaccine-related efforts in China.

A randomized, dose-finding study with didanosine plus stavudine versus didanosine alone in antiviral-naive, HIV-infected Thai patients

OBJECTIVES

To evaluate the safety and efficacy of four different regimens of didanosine (ddI) + stavudine (d4T) in HIV-infected Thais.

DESIGN

Prospective, open-label, randomized study.

METHODS

Patients were randomized to four regimens of high and low doses of ddI and d4T or to ddI alone. D4T was added to the ddI-alone arm after week 24. The duration of study was 48 weeks.

RESULTS

Seventy-eight patients were randomized (mean CD4 cell count, 255 x 10(6)/l; mean plasma HIV-1 RNA; 4.3 log10 copies/ml). In the intent-to-treat analysis, 78% of patients in the pooled combination arms and 20% of the patients in the ddI alone arm (to which d4T was added after 24 weeks) showed plasma HIV-1 RNA < 500 copies/ml at week 24 (P < 0.001), and 59% versus 53% at week 48, respectively. In addition, the proportion of patients with < 50 HIV-1 RNA copies/ml was 13% versus 7% at week 24 (P = 0.5) and 17% versus 20% at week 48 respectively. At week 24, median CD4 cell count increases from baseline were 101 x 10(6)/l in the pooled combination versus 76 x 10(6)/l in the ddI alone arm (P = 0.78). Logistic regression modeling suggested a correlation between receiving high dose ddI and achieving HIV-1 RNA < 500 copies/ml at week 48 (P = 0.07).

CONCLUSIONS

The d4T/ddI combination was superior to ddI alone in producing HIV-1 viral suppression. At week 48, > 60% of patients treated with this combination reached HIV-1 RNA levels < 500 copies/ml. Receiving high dose ddI but not d4T may correlate with a better viral suppression.

Drug resistance patterns, genetic subtypes, clinical features, and risk factors in military personnel with HIV-1 seroconversion

BACKGROUND

Regular testing of military personnel identifies early HIV infection; this identification provides a sentinel cohort in which to describe the evolving molecular epidemiology of HIV-1 transmission.

OBJECTIVE

To describe the prevalence and epidemiologic correlates associated with the acquisition of non-subtype B and drug-resistant HIV infections.

DESIGN

Cross-sectional study.

SETTING

Military referral hospital.

PATIENTS

95 military personnel with HIV-1 seroconversion.

MEASUREMENTS

Self-reported questionnaire, CD4 cell counts, plasma HIV-1 RNA levels, and nucleic acid sequence analysis for drug-resistant mutations and HIV-1 genetic subtype.

RESULTS

95 patients were enrolled between February 1997 and February 1998. The likely geographic location of HIV-1 acquisition was overseas in 8% of patients, the United States in 68%, and either overseas or the United States in 24%. Seven patients (7.4%) had subtype E infection; the remainder had subtype B infection. Eight of 31 (26%) treatment-naive patients had mutations in the reverse transcriptase or protease gene associated with drug resistance.

CONCLUSIONS

The percentage of HIV-1 non-subtype B infection and antiretroviral drug-resistant mutations was relatively high in U.S. military personnel with recently acquired HIV-1 infection.

Serologic and genetic characterization of HIV type 1 subtypes on Reunion Island

The aim of this study was to determine the HIV subtypes present on Reunion Island, a French island located in the Indian Ocean, where the first case of AIDS was diagnosed in 1987. Paired sera and blood samples were collected between September 1996 and September 1997 from 53 HIV-1-positive patients. Subtyping was performed by serotyping with a previously described subtype-specific enzyme immunoassay (SSEIA) and by genotyping with the heteroduplex mobility assay (HMA). When samples gave uninterpretable results with either of the methods, or discordant results, the V3 env region was sequenced and genetic subtypes were determined by phylogenetic analysis. Genetic subtyping showed that 48 of 53 patients were infected with HIV-1 subtype B (90.5%). This high prevalence of subtype B on Reunion Island is probably due to the regular exchanges with metropolitan France. The other five patients were infected with subtype A (9.5%); they had been directly linked to African populations. Of the 48 subtype B samples, 44 (91.7%) were correctly subtyped by SSEIA and 43 (89.6%) by HMA. However, the SSEIA did not allow the subtyping of A strains in three of five patients. Thus, the SSEIA could be an alternative routine technique for screening subtype B versus nonsubtype B HIV-1 strains.

V3 serotyping of HIV-1 infection: correlation with genotyping and limitations

HIV-1 V3 serotyping is a classification of immunodeficiency viruses based on antibody binding to V3 peptides that allows obtaining information on circulating subtypes that could be important for population-based epidemiologic studies. Recently, several laboratories have developed V3 enzyme-immunoassays (EIAs) using V3 peptides of subtypes A to E. In the present study, the utility of including additional peptides of subtypes F to H to the EIA was evaluated on a panel of 203 well-characterized serum samples from patients with diverse geographic origins (22 countries) and known HIV-1 genotype (79 A, 61 B, 21 C, 7 D, 7 E, 21 F, 6 G, 1 H). The results indicate a high predictive value (ppv) for serotypes B (> or =0.86), D (1) and E (0.88), and confirm the difficulty of predicting genotype A or C based on serotype A or C. Results also indicate that inclusion of the F peptide in the V3 EIAs may be useful (ppv = 0.61), but introduction of peptides G and H failed to demonstrate significant sensitivity or specificity for these subtypes. Correlation between serotyping and amino-acid sequences of the V3 region from 103 samples allowed the identification of key amino-acids that appear essential for subtype-specific seroreactivity.

Application of dried blood spot specimens for serologic subtyping of human immunodeficiency virus type 1 in Thailand

Dried blood spot (DBS) specimens were assessed as an alternative to plasma for human immunodeficiency virus type 1 (HIV-1) serotyping by V3 loop peptide enzyme immunoassay. Nested PCR capable of distinguishing HIV-1 subtypes B and E was used as the reference standard. Ninety-two percent of DBS samples were typeable as either HIV-1 subtype B or E. Serotype results with DBS and plasma were identical for 254 of 257 specimens. A simple DBS collection method provides a convenient alternative for conducting HIV-1 serotype surveillance while retaining sensitivity and specificity.

HIV type 1 subtypes in Malaysia, determined with serologic assays: 1992-1996

We investigated the molecular epidemiology of HIV-1 subtypes in Malaysia among injecting drug users (IDUs) and sexual transmission risk groups, using serologic and genetic techniques. Frozen sera collected at a general hospital, a blood bank, several drug treatment centers, and an STD clinic in Kuala Lumpur, between 1992 and 1996, were investigated retrospectively. V3 peptide serotyping and monomeric gp120 capture serotyping were used to study 89 known HIV-1-infected subjects. The methods differentiate subtypes B, E, and C. V3 peptide and gp120 capture results were comparable. No subtype C-specific reactive sera were found; one specimen was dually reactive for subtypes C and B, using the V3 peptide ELISA; and four were durally reactive for subtypes E and C using this assay. Genotypic analysis of HIV-1 gag RNA in serum was done on a subset of subjects and confirmed serologic findings. HIV-1 subtypes differed significantly by risk category: of 53 IDUs, 29 (55%) were infected with subtype B and 19 (36%) were infected with subtype E, 3 (6%) were dually reactive, and 2 (4%) were not typable. Of 36 persons with heterosexual risks, 29 (81%) were infected with subtype E, 5 (14%) were infected with subtype B, and 2 (5%) were not typable. Persons with IDU risks were significantly more likely to be infected with subtype B than were those with sexual risks (OR 5.89; 95% CI, 1.94-18.54; p < 0.001). Subtypes B and E of HIV-1 appear to predominate in Malaysia; subtype B was more prevalent among IDUs; subtype E was more prevalent among all other groups. These results may have important HIV-1 vaccine implications.

Molecular epidemiology and trends of HIV-1 subtypes in Taiwan

To understand the trends of distribution and risk factors associated with different HIV-1 subtypes in different populations in Taiwan, blood samples and questionnaires were collected from 267 male and 21 female HIV-1-infected people in a multicenter survey from 1993 to 1996. This group represented about one quarter of the total registered HIV-1 cases in Taiwan. The HIV-1 subtypes were determined using V3-based peptide-enzyme immunoassays complemented by heteroduplex mobility assay and phylogenetic tree analysis. The results showed that in Taiwan, men were primarily infected with HIV-1B (68.2%) and HIV-1E (27.3%), whereas women were mainly infected with non-B subtypes (4.8% A, 4.8% C, 71.4% E, and 9.5% G). In addition, 71.4% of men with HIV-1B were homosexual or bisexual, whereas 56.2% of men with HIV-1E were heterosexual (p < .001). Although HIV-1E subtype came to Taiwan later than HIV-1B, it has become a major subtype in the heterosexual population.

Nationwide surveillance of HIV-1 prevalence and subtype in young Thai men

As part of routine surveillance, an HIV-1 serosurvey of 366,074 members of successive cohorts of young Thai men entering service with the Royal Thai Army (RTA) was conducted between November 1989 and November 1995. We analyzed regional and temporal trends in HIV-1 seroprevalence in young men in Thailand and determined the proportion of infections resulting from subtypes E and B in this population in 1992 and 1995. The prevalence in 1992 was compared with that in 1995 by region and demographic group. The HIV-1 subtype was determined in a random sample of HIV-1-positive specimens in 1992 and 1995 using a V3 peptide enzyme immunoassay. From a peak of 3.7% in 1993, overall seroprevalence declined to 3.0% in 1994 and further in 1995 to 2.5%. Between 1992 and 1995, the absolute decrease in seroprevalence was greatest in the upper North (from 12.5% to 5.3%), where the prevalence has been the highest. Overall, 96.9% and 95.9% of typable specimens were determined to be subtype E in 1992 and 1995, respectively. Decline in HIV-1 seroprevalence among young men in Thailand has continued, which suggests that HIV control programs in Thailand may have been successful in decreasing spread of HIV-1. Almost all HIV-1 infections resulted from subtype E.

Risk factors for HIV-1 transmission from HIV-seropositive male blood donors to their regular female partners in northern Thailand

OBJECTIVE

To describe risks for HIV transmission from male blood donors to their regular female sex partners in Chiang Mai, Thailand.

DESIGN

Cross-sectional study.

METHODS

From March 1992 through September 1995, 405 HIV-seropositive male blood donors (index cases) and their regular female partners were enrolled in the study. Women with risk factors for HIV infection other than sexual contact with the index male were excluded. Couples were interviewed and examined; specimens were collected for laboratory analysis.

RESULTS

Overall, 46% of the 405 women enrolled were HIV-positive. Ninety-eight per cent of male index cases had a history of sex with a female prostitute; 1.5% reported always using condoms with their regular partner. History of sexually transmitted disease (STD) and swollen inguinal lymph nodes in the female partner were associated with an increased risk of HIV infection in the female. History in the female of genital herpes [odds ratio (OR), 3.46; 95% confidence interval (CI), 1.50-8.78], gonorrhea or chlamydia infection (OR, 2.71; 95% CI, 1.39-5.53), and stable relationship of longer than 24 months (OR, 2.28; 95% CI, 1.02-5.09) were associated with an increased risk of HIV infection in the female. Consistent condom use in the past 2 years (OR, 0.10; 95% CI, 0.01-0.79) was associated with a decreased risk of HIV infection in the female.

CONCLUSIONS

Married women in northern Thailand who appear otherwise to be at low risk for HIV infection may be exposed to this virus by their husbands. High rates of sex with commercial sex workers among men and low use of condoms within stable relationships may be important factors promoting the transmission of HIV in married couples. Programs to increase the regular use of condoms among married couples could be an important public health intervention to prevent transmission of HIV and other types of STD in northern Thailand.

The molecular epidemiology of HIV-1 among male sex workers in northern Thailand

Male commercial sex workers (CSWs) in northern Thailand are at high risk for HIV-1 infection and may be exposed to multiple subtypes of HIV-1 through sexual contact with men and women from Thailand, other Asian nations, and the West. We studied 103 male Thai nationals working in gay bars and clubs in Chiang Mai city who participated in the 1994 sentinel surveillance of the Thai Ministry of Public Health using HIV serologic testing, DNA polymerase chain reaction methods, molecular cloning, differential colony hybridization, nucleotide sequencing, and a third hypervariable region (V3) peptide enzyme-linked immunoabsorbent assay to differentiate subjects infected with HIV-1 subtypes B, E, both, or neither. The majority (58%) reported heterosexual orientation, and 35 (34%) were married. Seventeen (16.5%) were HIV infected: 16 (94%) of 17 had HIV-1 subtype E; 1 had HIV-1 subtype B. Two subjects had dually reactive results by molecular techniques but colony hybridization sequencing revealed only HIV-1 subtype E. HIV-1 subtype E appears to be the predominant clade among male CSWs in northern Thailand. This may have important implications for the global kinetics of the HIV epidemic.