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C Wasi

Publications and source records attributed to C Wasi.

At least 37 records · Page 2Linked to original sources
PubMed1999

Sendai virus-based production of HIV type 1 subtype B and subtype E envelope glycoprotein 120 antigens and their use for highly sensitive detection of subtype-specific serum antibodies.

We previously described a Sendai virus (SeV)-based expression system for the recombinant gp120 of HIV-1 subtype B (rgp120-B), which has permitted the production of antigenetically and functionally authentic gp120 at a concentration as high as 6 microg/ml of culture supernatant (Yu D et al.: Genes Cells 1997;2:457-466). Here the same procedure was successfully applied to the production of HIV-1 subtype E gp120 (rgp120-E). The remarkable production of the proteins by the SeV expression system enabled us to use crude culture supernatants for serological and functional studies of gp120s. The immunological authenticity of rgp120-E was verified by patient sera and anti-V3 loop monoclonal antibodies specific for HIV-1 subtypes B and E. CD4-binding properties were corroborated by FACS analyses. The rgp120s were then used in an enzyme immunoassay (rgp120-EIA) to detect antibodies in the sera of HIV-1-infected individuals, and the performance was assessed in comparison with a conventional V3 loop peptide EIA (V3-EIA). The initial evaluation of a serum panel (n = 164) consisting of 76 subtype E and 88 subtype B sera revealed that the rgp120-EIA was nearly 1000-fold more sensitive than the V3-EIA and was able to detect subtype-specific antibody with 100% sensitivity and with a complete correlation with the genotypes, whereas the V3-EIA failed to detect 9 and 24% of the same subtype E and B sera, respectively. Furthermore, a study employing a panel of 28 international sera with known genotypes (HIV-1 subtypes A through F) confirmed the remarkable specificity of this method. An EIA reactivity higher than 1.0 was an unambiguous predictor of HIV-1 subtype E and B infections. The data imply the presence of strong subtype-specific epitopes for antibody bindings to these rgp120s.

Antibodies, Viral↗
PubMed1999

Role of maternal humoral immunity in vertical transmission of HIV-1 subtype E in Thailand.

The significance of the maternal humoral immune response in relation to vertical transmission of HIV-1 was investigated in 123 mothers infected with subtype E from Thailand. Antibody binding titers to HIV-1 env domains (monomeric gp120, the CD4/gp120 binding site [BS], V3 loop, and gp41) and antibody-mediated neutralization of primary and T-cell line-adapted (TCLA) subtypes B and E HIV-1 isolates were investigated. No correlation between maternal anti HIV-1 antibodies at delivery and vertical transmission of HIV-1 subtype E was found. However, a trend to higher titer antibody-mediated cross-neutralization of a heterologous subtype B TCLA isolate, HIV-1MN, was observed in nontransmitting mothers postpartum. The HIV-1-specific antibody titers in these infected mothers increased significantly from delivery to 6 months postpartum (p < .05), but this was only partially attributable to hemodilution and an additional factor or factors appear to affect humoral immunity to HIV-1 during late pregnancy.

Adult↗
PubMed1999

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).

CD4 Lymphocyte Count↗
PubMed1998

Characterization of sera from subjects infected with HIV-1 subtypes B and E in Thailand by antibody binding and neutralization.

The range and specificity of the humoral immune response to HIV-1 subtypes B and E was investigated in Thai samples. Sera from HIV-1-positive subjects, consisting of subtypes B (n = 24) and E (n = 138), were characterized in relation to the neutralization of primary isolates and T-cell line-adapted (TCLA) strains and binding to monomeric gp120, the CD4/gp120 binding site (BS), and V3 peptides. A subtype-specific pattern of antibody binding was observed with the exception of the CD4/gp 120MN BS. Neutralization of TCLA strains (n = 4) was strongly type-specific (p = .002); however, neutralization of primary isolates (n = 8) was weak and group specific. Thus, the subtype specificity of B and E sera in the neutralization of TCLA strains, but not primary isolates, supports the dominance of the V3 region in TCLA virus neutralization but does not support the distinction of subtypes B and E as discrete neutralization serotypes in Thailand.

Amino Acid Sequence↗
PubMed1998

Infection with HIV-1 subtypes B and E in injecting drug users screened for enrollment into a prospective cohort in Bangkok, Thailand.

From May through August 1995, a cross-sectional survey was conducted among injecting drug users (IDUs) drawn from 15 drug treatment clinics in Bangkok and who were not known to be HIV-seropositive, to determine the prevalence of HIV-1 subtypes B and E and related risk behaviors, and to offer enrollment in a prospective cohort study. IDUs who voluntarily consented were interviewed, and blood specimens were tested for the presence of HIV antibodies. HIV-1-seropositive specimens were tested for subtypes B' (Thai B) and E by using V3 loop peptide enzyme immunoassays specific for these HIV-1 genetic subtypes. Of 1674 IDUs studied, the mean age was 31.2 years (interquartile range, 25-37 years), 94.8% were men, and 29.3% were HIV-1-seropositive. On multiple logistic regression analysis, HIV-1 seropositivity was associated with older age, not being married, less education, needle sharing, and incarceration. HIV-1 subtype B' accounted for 65% of prevalent infections and subtype E, 35%. Infection with subtype E was associated with younger age and did not seem to be associated with sexual risk behaviors, which were uncommon in general. Bangkok IDUs continue to be at high risk for HIV-1 infection related to needle sharing and incarceration. Although HIV-1 subtype B' accounts for most prevalent infections, subtype E seems to be more prevalent among younger IDUs, and most infections seem likely to result from parenteral transmission.

Adult↗
PubMed1998

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.

Adult↗
PubMed1998

HIV prevalence, risk, and partner serodiscordance among pregnant women in Bangkok. Bangkok Collaborative Perinatal HIV Transmission Study Group.

CONTEXT: Most prior studies of the human immunodeficiency virus (HIV) epidemic in Thailand have focused on commercial sex encounters; however, because the epidemic increasingly concerns stable heterosexual relationships, determining risk factors for this form of transmission is warranted. OBJECTIVES: To determine temporal trends in HIV prevalence, risk factors for HIV seropositivity, and rates of partner serodiscordance for pregnant women in Bangkok, Thailand. DESIGN: Retrospective review of hospital antenatal clinic HIV test results from 1991 through 1996. Baseline demographic and behavioral risk factors for HIV were assessed for subjects enrolled from November 1992 through March 1994. SETTING: Two Bangkok hospitals with routine antenatal clinic HIV counseling and testing. PARTICIPANTS: The HIV-positive pregnant women enrolled in a perinatal HIV transmission study and their partners and HIV-negative pregnant controls. RESULTS: From 1991 through 1996, antenatal clinic HIV seroprevalence increased from 1.0% to 2.3%. On multivariate analysis of data from 342 HIV-positive and 344 HIV-negative pregnant women, more than 1 lifetime sex partner, history of a sexually transmitted disease, and a high-risk sex partner were the most important factors for seropositivity (all P<.001). Twenty-six percent of partners of HIV-positive women were HIV negative. Women reporting more than 1 lifetime sex partner were more likely to have an HIV-negative partner than women reporting only 1 (45% vs 8%; relative risk, 5.5; 95% confidence interval, 3.2-9.5; P<.001); women reporting no high-risk behaviors were less likely to have an HIV-negative partner (10% vs 44%; relative risk, 0.2; 95% confidence interval, 0.1-0.4; P<.001). CONCLUSIONS: Prevalence of HIV in pregnant women has increased steadily in Bangkok from 1991 through 1996. Sex with current partners was the only identified risk exposure for about half (52%) of the HIV-positive women. Although few HIV-positive pregnant women reported high-risk behaviors, more than 1 lifetime partner and a partner with high-risk behavior were strong risk factors for seropositivity. Together with the unexpected finding that one fourth of partners of seropositive pregnant women were seronegative, these data emphasize that women in the general population are at risk for HIV because of the risk behavior of both current and previous partners.

AIDS Serodiagnosis↗
PubMed1998

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.

Aging↗
PubMed1997

Progress and achievement of rabies control in Thailand.

The breakthrough in production of highly efficacious human and animal rabies vaccines has led to successful rabies control in developed countries, but rabies is still a major health problem in many developing countries. In Thailand, the new cell culture vaccines-purified chick embryo cell (PCEC), purified Vero cell (PVRV), purified duck embryo (PDEV) and human diploid cell (HDCV) are available, and since 1993 have completely replaced the nervous tissue vaccines. The impact of these cell culture vaccines has been considerable, with the number of human rabies deaths decreasing from 200-300 in the early 1980s to 74 in 1995. Rabies prevention has also focused on the vaccination of dogs, and since 1992, the year the Rabies Prevention Act was announced, every owned dog has to be vaccinated at 2-4 months of age annually thereafter. However, only about 20% of dogs have been vaccinated. In 1995, the Ministry of Agriculture and Cooperation collaborated with the Ministry of Public Health to set up a target of no human rabies deaths in 1996, and a rabies-free Thailand by the year 2000. An extensive educational campaign is underway.

Animals↗
PubMed1997

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.

Adolescent↗
PubMed1997

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.

Adolescent↗
PubMed1997

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.

Adolescent↗
PubMed1997

Detection and typing of human papilloma virus DNAs in normal cervix, intraepithelial neoplasia and cervical cancer in Bangkok.

We detected and typed HPV-DNA by polymerase chain reaction (PCR) in cervico-vaginal lavages of 102 women with normal cervical cytology, 57 patients with cervical intraepithelial neoplasia (CIN), and 23 cervical cancer patients. HPV-DNA detection and typing by in situ hybridization were also performed in cervical biopsies from CIN lesions and cancers. Five percent of women with normal cervical cytology, 46% of CIN, and 61% of cervical cancer were positive for HPV-DNA. Of CIN cases with positive HPV-DNA, 69, 15, 8, 4 and 4% were HPV-16, -33, -18, -11 and -16/33 respectively. Of cervical cancer cases with positive HPV-DNA, 86% were HPV-16, 7% were HPV-16/33, 7% were HPV-18/31. HPV typing was performed in biopsies from 37 CIN and 18 cervical cancers by in situ hybridization. By this method, 38% of CIN were HPV-DNA positive, of which 71% were HPV-16 and 7% were each of HPV-11, -18, -31 and -33. Thirty-nine percent of cervical cancers were positive, of which 71% and 29% were HPV-16 and HPV-16/18 respectively.

Adolescent↗
PubMed1996

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.

Cell Line↗
PubMed1996

Analysis of neutralizing and enhancing antibodies to human immunodeficiency virus type 1 primary isolates in plasma of individuals infected with env Genetic subtype B and E viruses in Thailand.

Twenty-seven HIV-1 isolates were obtained from 51 asymptomatic HIV-1-infected pregnant women or intravenous drug users (IDUs) in Bangkok. Using heteroduplex mobility assay (HMA), it was found that the majority of the HIV-1 isolates (9 out of 11) from pregnant women belonged to genetic subtype E, whereas most of the subtype B HIV-1 isolates (15 out of 16) were isolated from IDUs. The HIV-1 isolates were tested for their susceptibility to neutralization or antibody-dependent enhancement with homologous and heterologous plasma of the two different genetic subtypes, B and E. Overall, HIV-1 neutralizing activity could be found in 37.3% of virus/plasma pairs for both subtypes B and E. No significant correlation could be identified between the two genetic subtypes (B and E) and their susceptibility to neutralization. Subtype B plasma demonstrated frequent cross-neutralization of subtype E viruses in 38.5% of virus/plasma pairs, whereas cross-neutralization activity of subtype E specific plasma samples was more limited and could cross-neutralize subtype B viruses only in 15.8% of cases. Some of the viral strains independently of their genetic subtypes were more susceptible to neutralization by plasma specific for both subtype E or subtype B, suggesting that this phenomenon is related to the proper biological properties of a viral strain. Antibody-dependent enhancement of HIV-1 strains could be detected in 12/83 (14.5%) virus-plasma pairs irrespective of genetic subtypes. Similar to neutralization results, the HIV-1 enhancing activity of plasma was mostly isolate-specific. The HIV isolates that were susceptible to neutralization were not enhanced by any plasma. On the other hand, the HIV isolates that were enhanced by plasma were resistant to neutralization in most cases. Such a dissociation between susceptibility to neutralization or enhancement may be indicative of the existence of discrete epitopes determining the two distinct viral properties.

Adult↗
PubMed1996

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.

Adult↗