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.

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.

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.

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.

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.

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.

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.

Detection of human cytomegalovirus in urine of infants by polymerase chain reaction.

Polymerase chain reaction (PCR), viral isolation and serological methods were used to diagnose HCMV infection in infants. Specimens of urine and clotted blood were collected from suspected cases of congenital or HCMV infection who attended the Pediatric Clinic, Siriraj Hospital. Prevalence of HCMV infection was found in 3 per cent of infants aged under 14 days and increased to 48 per cent in infants aged over 14 days. PCR was the most sensitive technique, it could detect HCMV infection in 29 per cent of the study infants, whereas, detection rate by isolation was 17 per cent and by specific IgM ELISA was 15 per cent. Sensitivity and specificity of PCR compared with isolation and/or serology were 93 per cent and 96 per cent, respectively. Detection of HCMV in urine by PCR can be used as a sensitive and rapid test for diagnosis of HCMV infection in infants.

Prevalence of human herpesvirus 6 in Thai people and its correlation with human immunodeficiency virus type 1 infection.

Human herpesvirus 6 (HHV-6) is a human herpesvirus isolated from patients with various lymphoproliferative disorders and acquired immunodeficiency syndrome (AIDS). The prevalence of HHV-6 infection and its correlation as a cofactor in pathogenicity of HIV infection was investigated in serum samples from 365 healthy volunteers at various age groups, 50 persons at risk for HIV-1 infection, and 90 HIV-1 seropositive individuals. Sera were screened and titrated for antibodies against HHV-6 by a standard indirect immunofluorescence assay on an acetone fixed HHV-6 infected HSB2 cells. The data show high prevalence of HHV-6 in Thailand (71.7%) and the infection is acquired early in life. Prevalence of anti-HHV-6 IgG antibodies was not strikingly different among people at risk for HIV infection, asymptomatic HIV-1 infected cases, and aged-matched controls with low risk for HIV-1 infection. The AIDS cases showed high titers of anti-HHV-6 IgG antibody and high rates for presence of anti-HHV-6 IgM antibody (33.3%) which suggests higher prevalence of HHV-6 infection by either reactivation of an earlier HHV-6 infection or a new primary infection.

Epstein-Barr virus serological markers for nasopharyngeal carcinoma in Thailand.

The present study reports on the prevalence of specific IgA and IgG antibodies to EBV viral capsid antigen in nasopharyngeal carcinoma (NPC) patients with different histological types of carcinoma and their age-matched controls by the indirect immunofluorescence test, using the B-95-8 lymphoblastoid cell line as source of viral capsid antigen. EBV specific IgG was found in almost all the study cases, and antibody titers were significantly higher in the NPC patients than in non-cancer controls. GMT of anti-EBV IgG in NPC patients, patients with other malignant diseases, and those with non-malignant diseases were 371.5, 97.7 and 35.5, respectively. Anti-EBV specific IgA was more specific to NPC than was IgG, and was present in 86.5% (83 of 96) cases of NPC patients, 6.6% (2 of 30) of patients with other cancers, and 3.1% (3 of 97) cases of non-malignant diseases. A weak correlation between level of anti-EBV IgA in NPC patients was observed (r = 0.3). EBV IgA was found in all histological types of NPC, ie, WHO types 1, 2 and 3, but WHO type 1 was rare among NPC patients in Thailand. Use of anti-EBV IgA for monitoring cancer therapy is to be further investigated.