Survey of reverse transcriptase from the heterosexual epidemic of human immunodeficiency virus type 1 CRF01_AE in Thailand from 1990 to 2000.

Genetic diversity of the HIV-1 envelope gene has shown a steady increase over time in the Thai and other regional epidemics. A serial survey of subtype CRF01_AE polymerase gene (RT) diversity in Thailand was performed, using 48 novel and 15 reported sequences covering the period 1990--2000. These sequences were gathered from individuals whose sole risk factor for infection was heterosexual contact. By contrast to envelope, diversity was low and, despite a 40% increase early in the epidemic, has remained static since 1996. These results indicate that epidemic HIV-1 may be constrained within defined limits of genetic diversity at least in some genomic regions.

Differential susceptibility of quiescent CD4+ lymphocytes to syncytial-inducing and non-syncytial-inducing isolates of HIV-1.

It is generally believed that quiescent CD4+ T cells are not susceptible to HIV-1 infection. However, infection of unstimulated peripheral mononuclear cells by syncytial-inducing (SI) viruses has been shown to be much more efficient than with non-syncytial-inducing (NSI) viruses. This suggested that SI, CXCR4-tropic viruses may be able to infect quiescent CD4+ T cells. We studied the infection of highly purified quiescent CD4+ T cells by SI and NSI viruses. In this article we show that although NSI viruses failed to significantly infect quiescent cells, SI viruses consistently infected these cells and produced viruses upon cellular activation by interleukin-2, 2 to 7 days after initial infection. To examine whether the difference was the result of viral or host factors, we purified CCR5+ quiescent CD4+ T cells and showed that these cells can be infected by dual tropic (R5X4) but not by R5 virus. This indicated that CCR5+ quiescent T cells were also susceptible to HIV-1 infection, and the failure of NSI, CCR5-tropic viruses to infect quiescent cells may be due to some intrinsic properties of these viruses.

Viral load differences in early infection with two HIV-1 subtypes.

OBJECTIVES: Information on early HIV-1 infection has come primarily from studies of persons infected with subtype B in North America and Europe; much less is known about other subtypes. The purpose of the present study was to compare the virologic and immunologic parameters following seroconversion among recently-infected persons infected with either of two different HIV-1 subtypes. METHOD: A prospective cohort study was carried out at methadone treatment clinics administered by the Bangkok Metropolitan Administration, Thailand. A total of 130 HIV-1-infected seroconverters (103 with HIV-1 subtype E and 27 with subtype B) were included in the study. The main outcome measures were serial HIV-1 RNA viral load, natural killer cell percentage, CD4 and CD8 lymphocyte counts since seroconversion. RESULTS: The demographic and behavioral characteristics of persons with either subtype were similar. Median RNA viral levels at the earliest time within 3 months of seroconversion were more than three times higher for persons infected with subtype E than subtype B (63 100 versus 18 050 copies/ml, P = 0.001). However, this difference decreased over time such that viral loads were similar at 12, 18, and 24 months following seroconversion. The CD4 and CD8 lymphocyte counts were similar in infections with either subtype during the entire period up to 24 months post-seroconversion. CONCLUSIONS: Higher viral loads associated with subtype E may result from inter-subtype biological differences; however, the epidemiological dynamics of transmission in Bangkok may have also contributed to this phenomenon.

Penicillium marneffei: types and drug susceptibility.

The PCR fingerprints of 30 Penicillium marneffei isolates from Chiang Rai in Northern Thailand and Bangkok in central Thailand were studied through use of single-nucleotide primers (GACA)4 and the phage M13 core sequence. Discrimination of fingerprint patterns was based on differences in the number of major bands. The P. marneffei isolates were divided into four types, i.e., A, B, C, and D. Type A was found in two isolates from Chiang Rai (6.7%). Types B and C respectively were found in two (6.7%) and one (3.3%) isolates from Bangkok. The predominate type D (83.3%) was found in isolates obtained from Chiang Rai and Bangkok. The PCR fingerprinting method was found to be useful for the epidemiological study of P. marneffei, a dimorphic opportunistic fungus and an emerging pathogen in the HIV pandemic. In vitro drug susceptibility testing by broth macrodilution to four antifungal agents against the yeast form of P. marneffei was performed. The MIC ranges for amphotericin B, fluconazole, itraconazole, and ketoconazole were 0.125-0.5, 4.0-8.0, < 0.032, and < 0.125 microgram/ml respectively.

Molecular and phenotypic characteristics of neurotropic HIV-1 subtype E.

Although HIV-1 subtype E associated with neurological dysfunction is common, the virological characteristics of HIV-1 isolated from the CNS for this subtype have not yet been identified. In this study, paired blood and CSF isolated from patients with AIDs-defining illnesses were cultured, sequenced and aligned. Phylogenetic tree and nucleotide-distances from both blood and CSF were investigated. Cytopathicity and co-receptor usage of paired blood and CSF isolates were compared to define the specific characteristics of CNS isolates. The results confirmed that CSF isolates showed less cytopathicity. It was found that both blood and CSF isolates used either CXCR4 or CXCR4 and CCR5 as co-receptors. Interestingly, one CSF isolate using CCR3 as a co-receptor was identified. By sequence analysis, the pair-wise distances of envelope gp 120 sequence and those of all variable regions (except V3 region) between blood and CSF isolates were significantly different. The genetic distances in V1/V2 regions of CSF isolates showed more diversity than those of blood isolates. These findings suggest that the evolution of V1/V2 regions of CSF isolates seems to be an advantage for HIV-1 in CNS infection. In contrast, the genetic distance in V4 and V5 regions of CSF isolates showed less diversity, suggesting that conservation in these regions might be necessary during the process of HIV-1 CNS infection.

Toxoplasma gondii antibodies in HIV and non-HIV infected Thai pregnant women.

Serological evidence for Toxoplasma gondii infection in Thai pregnant women was investigated. One thousand six hundred and sixty-nine blood specimens were collected from 838 HIV-seropositive and 831 HIV-seronegative pregnant women attending the antenatal-care clinic at Siriraj Hospital, Bangkok, Thailand, during a two-year period. Toxoplasma IgG antibody was detected, using a solid-phase enzyme-linked immunosorbent assay in which the membrane protein p-30 was the predominant antigen. IgG positive sera were subsequently examined for IgM antibody by the capture antibody enzyme immunoassay. The IgG antibody was found in 450 (53.7%) HIV seropositive women and 44 (5.3%) non-HIV infected women, with a statistically significant difference (p < 0.0001). Three of the 450 HIV-seropositive and 2 of the 44 HIV-seronegative sera with IgG antibody were positive for IgM antibody against T. gondii. This result suggested that HIV seropositive pregnant women had a higher risk of Toxoplasma infection with increase exposure to their offspring.

Diversity of HIV-1 subtype E in semen and cervicovaginal secretion.

OBJECTIVES: To characterize human immunodeficiency virus type 1 (HIV-1) subtype E variants in blood and genital fluid of infected Thai couples. STUDY DESIGN/METHODS: Blood and genital fluid were collected from 30 asymptomatic healthy HIV-1 subtype E infected couples from Bangkok, Thailand from 1995 to 1998. RESULTS: All 60 viruses in blood samples were identified as subtype E by heteroduplex mobility assay. The biotype of viruses founded in blood was syncytium-inducing (SI), whereas M-tropic and non-syncytium-inducing (NSI) isolates were predominantly detected in genital fluid. HIV-1 proviral DNA was detected in 43.33% and 56.67%, and viral RNA was detected in 93.33% and 56.67%, of semen (n = 30) and cervicovaginal secretion (n = 30) samples tested, respectively. A higher intersample genetic distance and more positive charge of the V3 loop were found in blood strains composed of genital fluid strains (22.30 +/- 5.92% and 17.96 +/- 6.3%), which was statistically significant (P = 0.003). The env V1-V4 intraperson variation of the HIV-1 subtype E in the blood and genital fluid of each individual was in the range 3.0%-5.7%. We also determined the intrasample variation of HIV-1 from blood and genital fluid by heteroduplex mobility assay. The mean heteroduplex mobility of the HIV-1, V1-V4 region of env gene, in blood (n = 8) and genital fluid (n = 8) was 0.59 +/- 0.06 and 0.74 +/- 0.11 (t test, p = 0.001), respectively. CONCLUSIONS: There was genetic and phenotypic compartmentalization of HIV-1 subtype E in blood and genital fluid with the presence of SI and NSI phenotypic variants as a common property of subtype E isolates from blood and genital fluid, respectively.

Genetic characterization of incident HIV type 1 subtype E and B strains from a prospective cohort of injecting drug users in Bangkok, Thailand.

We obtained specimens from 128 HIV-1 seroconverters identified from 1995 through 1998 in a prospective cohort study of 1,209 HIV-negative injecting drug users (IDUs) in Bangkok, Thailand. Epidemiologic data indicated that parenteral transmission accounted for nearly all infections. HIV-1 DNA from the C2-V4 env region was sequenced, and phylogenetic analyses determined that 102 (79.7%) of the specimens were subtype E and 26 (20.3%) subtype B strains. All subtype B strains clustered with strains often referred to in previous studies as Thai B or B'. The interstrain nucleotide distance (C2-V4) within subtype E strains was low (mean, 6.8%), and pairwise comparisons with a prototype subtype E strain, CM244, showed limited divergence (mean, 5.6%). The subtype B stains showed greater interstrain divergence (mean, 9.2%) and were significantly divergent from the prototype B strain HIV-MN (mean, 13.0%; p < 0.0001). The subtype E strains had significantly lower mean V3 loop charge than did subtype B strains (p = 0.017) and, on the basis of analysis of amino acid sequences, were predicted to be predominantly (91%) non-syncytium-inducing (NSI), chemokine coreceptor CCR5-using (CCR5+) viruses. The subtype B strains had a higher mean V3 loop charge, and a smaller proportion (23%) were predicted to be NSI/CCR5+ viruses. This study demonstrates that most incident HIV1 infections among Bangkok IDUs are due to subtype E viruses, with a narrow spectrum of genetic diversity. The characterization of incident HIV-1 strains from 1995 to 1998 will provide important baseline information for comparison with any breakthrough infections that occur among IDUs in Bangkok who are participating in an HIV-1 vaccine efficacy trial initiated in 1999.

Differential stability of the mRNA secondary structures in the frameshift site of various HIV type 1 viruses.

For many retroviruses, one or more ribosomal frameshift events are required for translation of the Gag-Pol precursor protein, which is subsequently processed into the structural and enzymatic proteins found in mature virions. A specific nucleotide motif, the slippery sequence, as well as a downstream mRNA secondary structure are generally believed to have roles in the frameshift event. In HIV-1, a particular stem-loop mRNA secondary structure has been proposed for subtype B. On the basis of this model, HIV-1 subtypes A, E, and F were found in this study to share a similar stem-loop structure predicted to have a lower thermodynamic stability as compared with HIV-1 subtypes B, C, and D. The potential impact of this differential thermodynamic stability on HIV-1 replication remains to be determined.

Primary infection of human herpesvirus 6 in children with vertical infection of human immunodeficiency virus type 1.

The role of human herpesvirus 6 (HHV-6) infection in 227 children born to human immunodeficiency virus (HIV)-seropositive mothers was investigated. Of 41 HIV-uninfected infants, 3 (7%) were positive for HHV-6 DNA in the first month of life, suggesting possible intrauterine infection. The cumulative infection rates of HHV-6 at 6 and 12 months of age were significantly lower in HIV-infected children (11% and 33%, respectively) than in uninfected children (28% and 78%, respectively; P<.001). There was an association between high CD4+ cell numbers (>15%) before HHV-6 infection and high HHV-6 infection rate. Twenty-two infants with HIV classed as Centers for Disease Control and Prevention stages N1 or N2 were studied for an association of HHV-6 infection with progression of HIV disease. Ten of the infants had HHV-6, and 12 did not. In 5 of the infants without HHV-6 (42%), HIV disease had not progressed by 1 year of age; however, HIV disease had progressed in all 10 children with HHV-6 infection. These results suggest an association of HHV-6 infection and progression of HIV disease in the study children with vertical HIV-1 infection (P<.05).

Effect of HIV-specific immune-based therapy in subjects infected with HIV-1 subtype E in Thailand.

OBJECTIVE: To examine the effect of treatment with an inactivated, gp120-depleted, HIV-1 immunogen (Remune) in 30 Thai subjects infected with HIV-1 subtype E. DESIGN: Sixty-week open-label study. METHODS: Thirty HIV-positive volunteers with CD4 cell counts > or = 300 x 10(6)/l were given intramuscular injections of Remune into the triceps muscle on day 1 and then at weeks 4, 8, 12, 24, 36, 48 and 60. RESULTS: Treatment with Remune was well-tolerated and augmented HIV-1-specific immune responses. Furthermore, subjects had a significant increase in CD4 cell count (P < 0.0001), CD4 cell percentage (P < 0.0001), CD8 cell percentage (P < 0.0001), and body weight (P < 0.0001) compared with pretreatment levels. Fourteen subjects with detectable viral load at day 1 showed a decrease at week 60 (P=0.04). Retrospective Western blot analysis showed 23 subjects with increased intensity of antibody bands and 15 patients showed development of new reactivities to HIV proteins, especially towards p17 and p15. CONCLUSION: These results indicate that HIV-specific immune-based therapeutic approaches such as Remune should be further examined in countries with different clades of HIV-1 and where access to antiviral drug therapies is limited.

V3 sequence diversity of HIV-1 subtype E in infected mothers and their infants.

To elucidate genetic characteristics of HIV-1 subtype E involved in vertical transmission, V3 regions of HIV-1 subtype E isolated from 17 infected mothers (M1-M17) and their infants (I1-I17) at 1 month after birth were sequenced after cloned into pCRII vectors. At least three clones of each sample were collected. All mothers were asymptomatic and had been infected through a heterosexual route. Nine infants (I9-I17) showed mild symptomatic and immunosuppression within the first year of life. The interpatient nucleotide distance of mothers and infants in this group (0.065+/-0.008) were of greater diversity than those of a nonimmunosuppression group (0.039+/-0.006) by a significant amount (Fischer's exact test, p = .003). The substitution with asparagine (N) at threonine (T) at position 13 and aspartic acid (D) at position 29 of the V3 sequence were significantly associated with nonimmunosuppression in the first year of life (F-test, p = 0.003). Either a single or multiple viral variants could transmit from mothers to their infants.

PIP: At least 1.5 million children worldwide are infected with HIV-1. Most HIV-infected children obtained the virus from their mother either in utero, at delivery, or postpartum through breast-feeding. Since the V3 loop of HIV is an important determinant for viral neutralization and cellular tropism, mutations in the V3 region could possibly affect mother-to-child transmission. Serum specimens from 17 HIV-1-seropositive mother-child pairs being treated at the pediatric clinic of Siriraj Hospital, Bangkok, in 1994 and 1995, were studied to better understand the genetic characteristics of HIV-1 subtype E involved in vertical transmission. The V3 regions of HIV-1 subtype E isolated from the subjects at 1 month after birth were sequenced after being cloned into pCRII vectors, with at least 3 clones of each sample collected. All mothers were asymptomatic and had been infected through a heterosexual route. 9 infants were mildly symptomatic and had evidence of immunosuppression during their first year of life. The nucleotide sequences of asymptomatic infants were significantly closer to maternal sequences than those of the AIDS cases. The data suggest that 1 or 2 genotypes from the mother were selected, transmitted to the infant, and then became diverse. The substitution with asparagine at threonine at position 13 and aspartic acid at position 29 of the V3 sequence were significantly associated with nonimmunosuppression during the first year of life.

Safety and immunogenicity of REMUNE in HIV-infected Thai subjects.

The safety and immunogenicity of REMUNE, an HIV-specific immune based therapy for HIV infection, was evaluated in a cohort of 30 HIV infected subjects in Thailand. This therapy utilizes a gp120 depleted inactivated virus (HZ321), which exhibits a high degree of conservation with the core antigens of both type B' and E strains of HIV, the predominant Thailand isolates. The treatment was well tolerated, with no serious adverse events reported over the course of the 4-month trial. Treatment in which four doses were administered with REMUNE appeared to boost HIV-specific immune responses, with approximately 75% of the treated subjects demonstrating an increase in either the repertoire or the intensity of the serological response to HIV as measured by Western blot. CD4%, viral load, and weight remained stable over the course of the 4-month study relative to baseline values. Viral subtyping of this cohort revealed a predominance of type 'E'. These data suggest that REMUNE is safe and immunogenic in seropositive Thai subjects and supports further study of the therapeutic potential of REMUNE to treat HIV-1 infection.

The reference range of CD4+ and CD8+ T-lymphocytes in healthy non-infected infants born to HIV-1 seropositive mothers; a preliminary study at Siriraj Hospital.

The results of CD4+, CD8+ T-lymphocyte values as percentage, number, and ratio were studied in infants aged 1 to 29 months. The 283 subsequent blood samples from 89 infants born to HIV-1 seropositive mothers were investigated. From 208 sequential samples of 70 healthy non-infected infants, the reference values of CD4+ and CD8+ T-lymphocytes have been established and compared to Caucasian reference values. The results were analysed in 4 difference age groups (1-5, 6-11, 12-17 and > or = 18 months). At age 12 months, CD4 number and percentage declined significantly while CD8 percent increased. At age 6 months CD4/CD8 ratio decreased. Of 19 infected infants CD4+ percentage and number as well as CD4/CD8 ratio declined at age 6 months and showed significant differences from uninfected infants. A significantly elevated CD8 percentage was demonstrated in infected infants at age of 12 months. In 9 infants who showed symptoms at age 6-18 months, the CD4 and CD8 values were different from the reference range and 6 of 9 patients showed lower CD4 percentage, CD4 number and reversed CD4/CD8 ratio before the symptoms appeared. In 10 infants who were asymptomatic at age 18 months, there was no evidence of immunosuppression at age 6 months or before. After age 6 months, lymphocyte subset values of some asymptomatic infected children were beyond the reference range. These preliminary findings should be very useful for monitoring children born to HIV infected mothers. The results of CD4+ and CD8+ T-lymphocytes in uninfected infants could be used as reference values for the Thai and other Southeast Asian pediatric populations.

Shedding of HIV-1 subtype E in semen and cervico-vaginal fluid.

The uneven expansion of HIV-1 subtypes in each transmitted group raises the possibility that some viruses have less/more potential by qualitative/quantitative for heterosexual transmission compared to others. In Thailand, HIV-1 subtype E is mainly spread via heterosexual route and accounts for about 95 per cent of the infected cases. To determine whether high sexual infectivity of HIV-1 subtype E is due to the presence of a virus in genital fluid, we conducted a study to characterize shedding of HIV-1 in seminal and cervico-vaginal fluids of 30 HIV-1 subtype E infected Thai couples by PCR and virus isolation methods. All subjects had no HIV-associated diseases and other sexually transmitted diseases. HIV-1 subtype E DNA was detected in 22/30 (77.33%) of cervico-vaginal and also 22/30 (77.33%) of seminal fluid samples. The isolation rate of HIV-1 from semen and cervico-vaginal secretion was 36.67 per cent and 16.67 per cent, respectively. Number of HIV-1 subtype E DNA copies in the blood is reversely correlated with the number of blood CD4+ T cells, while that in genital fluid was not related to CD4+ T cell count. An increase in shedding of HIV- DNA subtype E in female genital tract compared to other HIV subtypes reported by other investigators might be one reason to explain the rapid spread of subtype E by heterosexual transmission in Thailand.

PIP: Preliminary evidence suggests that HIV subgroups differ in both their transmissibility and virulence. In Thailand, HIV-1 subtype E (accounting for almost 95% of total HIV cases) is transmitted primarily through heterosexual sex, with a predominance of female-to-male infection. This study characterized virus shedding patterns in seminal and cervico-vaginal fluids from 30 asymptomatic husband-wife pairs from Bangkok, Thailand, known to be infected with HIV-1 subtype E. HIV-1 subtype E was detected in 22 (77.3%) cervico-vaginal and 22 (77.3%) seminal fluid samples. HIV-1 subtype B, in contrast, is found in only 30-50% of cervico-vaginal specimens; detection of subtype B in seminal specimens (70-80%) is comparable to that identified for subtype E in the present study. The isolation rate of HIV-1 was 36.67% from semen and 16.67% from cervico-vaginal secretions. The number of HIV-1 subtype E DNA copies in blood--but not in genital fluids--was inversely correlated with the number of blood CD4+ T cells. The increased shedding of HIV-1 DNA subtype E compared with other subtypes in the female genital tract presumably accounts for the rapid spread of subtype E among heterosexuals in Thailand.

Immune status in congenital infections by TORCH agents in pregnant Thais.

A cross-sectional, sero-epidemiological survey of the prevalence of antibodies to TORCH agents during various stages of gestation revealed an overall rate of 13-15 percent having antibodies to Toxoplasma gondii; 85-87 percent, to rubella ; 79-81 percent, to herpes simplex virus (HSV); 100 percent, to cytomegalovirus (CMV); 82-86 percent, to human herpes virus type 6 (HHV-6); 1-2 percent, to hepatitis C virus (HCV). None of human T lymphotropic virus type I (HTLV-I) antibody was detected, and a prevalence of hepatitis B surface antigen (HBsAg) was 6 percent. Although a tendency was noted towards an increase of antibody detection to each TORCH agent as gestation progressed, a statistically significant increase in antibodies titer and specific IgM antibody was found with regard to CMV. These results suggest an increase in CMV infection or reactivation during pregnancy whereas an increase in the other TORCH infections was not obvious.

Maternal and viral factors in vertical transmission of HIV-1 subtype E.

Vertical transmission of HIV-1 is caused by multifactorial factors. To access the relationship of viral factors involving in perinatal transmission of HIV-1 subtype E, which is the predominant type in Thailand, plasma viral load, blood CD4+ lymphocyte level, heteroduplex mobility, and V3 sequence of the HIV-1 envelope gene were studied in 32 transmitting and 25 non-transmitting mothers. We found that HIV-1 subtype E vertical transmission was strongly associated with high maternal plasma viral RNA (> 4 x 10(4) copies/ml) and high genetic diversity of envelope gene determined by heteroduplex mobility (< 0.9). The variation of nucleotide sequences in envelope gene of subtype E vertical transmission could not determine in V3 region. Hence, plasma viral load and heteroduplex mobility can be used as prediction factors in vertical transmission of HIV-1 subtype E.

V3 peptide enzyme immunoassay for serotyping HIV-1 infected pregnant Thais.

Previous molecular epidemiological studies show that at least 2 subtypes of HIV-1 circulate in Thailand. HIV-1 subtype B or Thai genotype B was associated with an early epidemic and was prevalent in intravenous drug users. Meanwhile, HIV-1 subtype E or Thai genotype A was becoming widespread among heterosexuals. We studied the HIV subtypes of 161 HIV-1 seropositive pregnant women. Of these, 143 pregnant patients (88.8%) tested positive for subtype E alone and 8 women (5.0%) had evidence of infection with subtype B alone. There was serologic evidence of infection with a mixture of subtypes in 7 women while the infecting subtype could not be identified in the remaining 3 women. This result agrees with previous information that subtype E predominates in Thai heterosexuals.

Detection of HIV-1 proviral DNA by polymerase chain reaction: a preliminary study in Bangkok.

Nested polymerase chain reaction (nested PCR) was used to separately amplify part of gag, pol, and env genes of human immunodeficiency virus type 1 (HIV-1) to evaluate that primer specific to either gag (SK380/390&SK38/39), pol (JA17/18&JA19/20), or env (JA9/10&JA11/12) genes is suitable for HIV-1 PCR based diagnosis in Thailand. The positive PCR results in 70 HIV-1 infected adults are 100, 97, 89 per cent and in 75 HIV-1 infected infants are 100, 94, 74 per cent by gag, pol, env primer, respectively. The specificity of all three primer sets is 100 per cent. The unamplified samples by pol and env primers were identified as HIV-1 subtype E by PELISA method. False negative in HIV-1 PCR based diagnosis caused by high genetic variation of HIV-1 can be overcome by using several primer sets as shown in this study.

HIV-1 Langerhans' cell tropism associated with heterosexual transmission of HIV.

Heterosexual transmission by vaginal intercourse accounts for most transmission of human immunodeficiency virus-type 1 (HIV-1) in Africa and Asia but is less important in the HIV-1 epidemics of the United States and Western Europe. Epithelial Langerhans' cells (LCs) represent a possible source of initial cell contact for vaginal infection. Fifteen primary isolates of HIV-1 from U.S. homosexuals and 18 HIV-1 isolates from Thailand heterosexuals were evaluated for growth in LCs of U.S. origin. All the viruses from the Thai heterosexuals, which were subtype E, grew more efficiently in the LCs than any of the viruses from the U.S. homosexuals, which are subtype B. These results suggest that LC tropism is associated with the efficiency of heterosexual transmission of HIV.