HIV type 1 in Thailand, 1994-1995: persistence of two subtypes with low genetic diversity.

Extensive transmission of human immunodeficiency virus type 1 (HIV-1) in Thailand began in 1988, resulting in an estimated 800,000 cumulative infections by 1994. During 1994 and 1995, we collected blood specimens from 215 asymptomatic HIV-1-infected people with various risk behaviors from nine locations in all four regions of Thailand. HIV-1 subtypes and genetic heterogeneity were determined for 214 strains by a combination of direct DNA sequencing (n = 95), subtype-specific oligonucleotide probe testing (n = 201), and V3-loop peptide enzyme immunoassay (PEIA) (n = 214). All strains were either env subtype E (175; 81.8%) or B (39; 18.2%). Of the subtype B isolates, 37 (94.9%) were B' and 2 (5.1%) were more typical North American-like B strains (most subtype B strains in Thailand are part of a distinct subcluster within the subtype B branch on phylogenetic trees, termed B'; formerly Thai B or BB). Of 149 viruses from people with sexual risk behaviors from all regions, 146 (98.0%) were subtype E. Of 65 viruses from injecting drug users (IDUs), 29 (44.6%) were subtype E and 36 (55.4%) were subtype B, including 35 B' strains. There was regional variation in the proportions of subtypes E and B' among IDUs. The intrasubtype nucleotide divergence within the V3 and flanking regions of the env gene (mid-C2 to the start of the V4 region) was low (5.7% for subtype E and 3.1% for subtype B') compared with other HIV-1 group M subtypes from different countries. These findings of two subtypes with low heterogeneity indicate that Thailand may be a desirable setting for evaluating candidate HIV-1 vaccines. The mix of subtype E and B' strains among IDUs also offers the opportunity to study phenotypic differences between the two subtypes.

PIP: The extensive transmission of HIV-1 in Thailand which began in 1988 led to an estimated 800,000 cumulative infections in the country by 1994. The authors collected blood specimens during 1994 and 1995 from 215 asymptomatic HIV-1-infected people with various risk behaviors from 9 locations across Thailand. HIV-1 subtypes and genetic heterogeneity were then determined for 214 strains using a combination of direct DNA sequencing, subtype-specific oligonucleotide probe testing, and V3-loop peptide enzyme immunoassay. 175 strains were subtype E and 39 were subtype B. 37 of the subtype B isolates were B' and 2 were more typical North American-like B strains. Of 149 viruses from people with sexual risk behaviors from all regions of the country, 146 were subtype E. Of 65 viruses from IV drug users (IVDUs), 29 were subtype E and 36 were subtype B, including 35 subtype B' strains. Regional variation was observed in the proportions of subtypes E and B' among IVDUs. The intrasubtype nucleotide divergence within the V3 and flanking regions of the env gene was 5.7% for subtype E and 3.1% for subtype B'. The finding of 2 HIV-1 subtypes with low heterogeneity suggests that Thailand may be an appropriate setting in which to evaluate candidate HIV-1 vaccines. The mix of subtype E and B' strains among IVDUs will also allow the study of phenotypic differences between the 2 subtypes.

Coxsackie B virus infection and myopericarditis in Thailand, 1987-1989.

Serum specimens of 363 myopericarditis patients from the hospital all over the country were examined for coxsackie B virus antibody during 1987-1989 by means of microneutralization test in order to assess association between myopericarditis and coxsackie B virus infection. The data established that certain virus infection rates were 24.3%, 19.4% and 23.6% respectively, no differences in incidence were found between sex (p > 0.05) and the incidence rate between age groups below 15 years and 15 years and older was significantly different (p < 0.05). It was found that the epidemic happened throughout the year and the most common serotype in 1987 and 1989 was B4 whereas in 1988 it was B3.

The latency rate of human herpesvirus 6 (HHV6) in positive and negative human immunodeficiency virus (HIV) infection of intravenous drug users (IVDU).

The seropositive and latency rates of HHV6 among IVDU with positive and negative HIV and control group were demonstrated. By immunofluorescent antibody test, no differences in the seropositive rates were found among these three groups. All groups had seropositive rate at the average 89% and GMT antibody 1:26. This meant that most of them had previous infection with HHV6. In addition, HHV6-DNA was determined and classified into subgroups: HHV6A and HHV6B, by polymerase chain reaction. The prevalence of HHV6-DNA indicated HHV6 latency in vivo. High latency rate of HHV6 was found in all three groups (the average 54%). Moreover, HHV6B (49%) had a higher frequency than HHV6A (5%); HHV6a was found only in IVDU with or without HIV infection. The result suggested that the HHV6 latency in IVDU with positive HIV may possibly transactivate HIV. The pathogenesis of HHV6 in AIDS patients should be further investigated. However, this research finding is useful for treatment, health care, prevention and control of AIDS in case of dual infections and latency of herpesvirus infection in AIDS.

Serological and genomic characterization of porcine rotaviruses in Thailand: detection of a G10 porcine rotavirus.

A total of 557 fecal specimens collected from piglets with diarrhea in Thailand were examined for rotavirus RNA by polyacrylamide gel electrophoresis. Twenty-three, one, and two samples were positive for group A, group B, and group C rotaviruses, respectively. Two samples exhibited two segments found in picobirnavirus RNA. RNA electropherotyping of 23 group A rotaviruses showed that they were classified into five patterns. By serotyping by enzyme-linked immunosorbent assay and PCR, viruses in 3 and 14 specimens were found to be serotype G3 and serotype G10, respectively. For one specimen, containing a serotype G10 virus (strain P343), virus was isolated in MA-104 cells, and the nucleotide sequences of the VP7 and VP4 genes were determined. Comparative sequence analysis and cross-neutralization tests showed that strain P343 has B223-like G10 and UK-like P7 serotype (or VP4 genotype 5) specificities. Rotaviruses having such antigenic specificities have not been detected in piglets. Thus, the interspecies transmission of rotaviruses between cows and pigs was suggested.

Treatment of herpes zoster with Clinacanthus nutans (bi phaya yaw) extract.

A randomized, placebo-controlled trial of the efficacy of topical formulation of Clinacanthus nutans (Bi Phaya Yaw) extract was carried out in 51 patients with varicella-zoster virus infection. The study medication was applied five times daily for 7-14 days until the lesions were healed. The number of patients with lesion crusting within 3 days and with lesion healing within 7 days and 10 days were significantly greater in the C. nutans extract-treated group than the placebo group (p < 0.01). Pain scores were reduced more rapidly in the C. nutans extract-treated group than in the placebo group. There were no side effects of the study medication.

Production of monoclonal antibody against hepatitis B surface antigen.

HBV infection is a major health problem in Southeast Asia. Thailand is considered to be an endemic area of HBV infection(18). Prevalence of HBsAg carriers is 5.2 per cent in children, 9 per cent in adults and 5.6 per cent in pregnant women(19,20). We believe that the monoclonal antibody described in the present report will be useful to develop HBsAg-KIT for national serologic screening assay, as considered in terms of sensitivity, specificity and cost effectiveness.

Distinct yearly change of serotype distribution of human rotavirus in Thailand as determined by ELISA and PCR.

A total of 241 group A rotavirus-positive stool samples collected from diarrhoeic patients in Thailand between July 1988 and June 1991 were characterized for their serotypes by enzyme-linked immunosorbent assay (ELISA) using serotype-specific monoclonal antibodies and by a polymerase chain reaction (PCR). In July 1988-June 1989, serotype 1 was the most prevalent (63.4%), followed by serotype 4 (11.0%) and serotype 2 (8.5%). In July 1989-June 1990, 59.8% were serotype 1, 24.3% were serotype 2, and 6.1% were serotype 3. In contrast, in July 1990-June 1991, serotype 3 was detected in the highest frequency (40.5%), 29.9% were serotype 1, and 27.3% were serotype 2. Thus, a distinct yearly change of serotype distribution of rotavirus in Thailand was observed in the three consecutive years. In particular, it was of note that the prevalence of serotype 3 greatly increased, in contrast to the previous studies in which almost no serotype 3 rotaviruses were detected in the years 1983-8 in Thailand.

Molecular and antigenic analyses of serotypes 8 and 10 of bovine rotaviruses in Thailand.

Antigenic and genomic properties of non-serotype 6 bovine rotaviruses isolated in Thailand and Japan were studied by cross-neutralization tests, nucleotide sequence determination of the VP7 gene, and RNA-RNA hybridization. Two Thai strains (61A and A44) were serologically related to a Japanese isolate KK3 which has been assigned to serotype 10. In contrast, strain A5 was found to be antigenically similar to human strain 69M with serotype 8 specificity, although strain A5 showed a one-way cross-reaction with serotype 6 strain NCDV. VP7 sequence analysis confirmed these results. High degrees of similarity in nucleotide and amino acid sequences (92.5 to 98.2% and 96.3 to 97.9%, respectively) were found among the VP7 genes of the four serotype 10 bovine strains (61A, A44, KK3 and B223). The VP7 amino acid sequence of strain A5 was similar to those of serotype 8 human strains (91.7% and 94.8% for strains B37 and 69M, respectively). In RNA-RNA hybridization experiments, a high level of overall relatedness was found among the three serotype 10 bovine strains (61A, A44 and KK3), and strains A5 and NCDV were also moderately related to the three serotype 10 viruses. All the bovine rotaviruses tested in this study, regardless of their serotype specificity, exhibited a moderate genetic-relatedness to strain 69M of serotype 8, and, to a lesser extent, to serotype 2 human rotavirus strains.

Human herpesvirus 6 (HHV-6) infection and exanthem subitum in Thailand.

Of 50 patients in Thailand suspected clinically of having exanthem, subitum, 31 (62%) were serodiagnosed as HHV-6 infection. Sixteen strains of HHV-6 from 31 patients (52%) whose antibody titers had converted during convalescence were isolated during the acute phase. The disease occurred in infants from 3 months to 1 year of age and most frequently at age 4-6 months. Antibody only to HHV-6 converted in 23 of 50 patients (46%), and seroconversion to HHV-6 and dengue virus was observed in 7 patients (14%), and to HHV-6 and Coxsackie B virus in 1 case (2%). In the 23 patients in whom seroconversion only to HHV-6 was observed, all had fever and rash which appeared after subsidence of the fever. Lymphadenopathy and relative lymphocytosis were recognized, associated with diarrhea, vomiting, running nose, cough and hepatomegaly. Febrile convulsions were seen in some cases. All patients recovered completely within a week.

Serological and genetic characterization of bovine rotaviruses in Thailand by ELISA and RNA-RNA hybridization: detection of numerous non-serotype 6 strains.

A total of 62 fecal specimens positive for rotavirus were collected from diarrheic cows in Thailand in 1988 and 1989. The antigenic properties of rotaviruses in stool were examined by enzyme-liked immunosorbent assays using specific monoclonal antibodies directed at VP4, VP6 or VP7: all the bovine rotavirus strains were determined as subgroup I; none of the strains were reactive with serotype 6-specific monoclonal antibody; and different reactivities of the bovine strains with two anti-VP4 monoclonal antibodies were observed. Polyacrylamide gel electrophoresis of viral RNA exhibited three different RNA electropherotypes. In RNA-RNA hybridization experiments using cell culture-adapted three strains as well as a reference bovine strain (NCDV), RNA from the Thai bovine strains showed very low homology to that from NCDV; only three or four RNA segments were hybridized between the RNAs from Thai samples and NCDV. These results suggested that bovine rotaviruses isolated in Thailand are serologically and genetically distinct from a reference serotype 6 bovine strain, NCDV.

Detection of 27-32 nm virus-like particles in stools of non-A, non-B hepatitis patients in Thailand by immunoelectron microscopy.

A total of 142 sporadic cases of viral hepatitis in Thailand were tested for HAV and HBV infections. Thirty nine and 58 cases were serologically found to be associated with HAV and HBV infections, respectively. The remaining 45 cases were unrelated to infection by HAV or HBV. In nine of these cases, we detected 27-32 nm virus-like particles in stools by immunoelectron microscopy using a reference serum of enterically transmitted non-A, non-B hepatitis (Fausta 3/87). This finding implies that enterically transmitted non-A, non-B hepatitis is prevalent also in Thailand.

Immunofluorescence, enzyme-linked immunosorbent assay, particle agglutination and western blot for the detection of antibody to human immunodeficiency virus type 1.

Immunofluorescence assay (IFA) has been applied for detection of antibody to human immunodeficiency virus type 1 (HIV-1). To compare the IFA with an enzyme-linked immunosorbent assay (ELISA) and particle agglutination (PA), we examined the antibody response to HIV-1 in 475 sera from AIDS, PGL and ARC patients as well as several risk groups and healthy persons by three methods. The positive results by any methods were confirmed by western blot (WB). The results by all methods were well correlated on the sera from 45 asymptomatic male homosexuals and 70 female prostitutes. There were some false positive results by ELISA in the sera from prisoners and healthy persons. Four sera from drug abusers were positive only by PA and IFA and were negative by ELISA. All were WB-inconclusive. Particle agglutination and IFA results were compared with western blot analysis on 208 ELISA-positive sera. All IFA-strongly positive sera (84%) were positive by western blot. The sera with weakly positive, negative and inconclusive results by IFA (16%) were possibly any of positive, inconclusive or negative by western blot. By PA, 200 of 208 (97%) sera were PA-positive and 1% of these sera were WB-inconclusive while the PA-negative sera were either negative or inconclusive by western blot. These results suggested that PA is a simple and sensitive method for screening of HIV-1 antibody while IFA could be a primary confirmatory test and western blot would then be used for confirming any IFA-negative or inconclusive results.

Subgroup and serotype distributions of human, bovine, and porcine rotavirus in Thailand.

The subgroup and serotype specificities of human, bovine, and porcine group A rotaviruses in stool specimens collected in Thailand were examined by an enzyme-linked immunosorbent assay by using subgroup- and serotype-specific monoclonal antibodies. A clear yearly change was observed in the serotype distribution of human rotavirus. Between 1983 and 1984, serotype 4 was the most prevalent, while the highest frequency of serotype 2 was found between 1987 and 1988. All the bovine and porcine rotaviruses examined showed subgroup I specificities and long RNA patterns. It was of note that serotype 3 porcine rotaviruses were found at a high frequency.

Prevalence of antibody to human herpesvirus 6 in women and children.

The antibody prevalence to human herpesvirus 6 (HHV-6) was compared between pregnant women and control women of similar ages in Thailand. No significant difference was detected in the antibody positive rate and antibody titers between both groups. The antibody titers in sera collected from pregnant women at 1st and 3rd trimester remained unchanged. Next, the antibody prevalence in infants were examined and the positive rate decreased until 3 months and started to increase from 6 months after birth. The present results suggest that the reactivation of HHV-6 might not occur during pregnancy and this virus infects infants postnatally.

A long term study of rotavirus infection in Thai infants and children with diarrhoea.

During 1977-1980, human rotavirus was detected by electron microscopic technique in the stool of 55 (30.7%) of 179 patients, hospitalized in Bangkok Metropolis. Characteristic particles 65-70 nm in diameter, round shape, resembling a little wheel with radius capsomeres from the dense core. Other some adenovirus and small virus particles were seen, 2.8% and 2.2% respectively. Seasonal distribution among Thai patients with rotavirus infection mostly occurred in January (58.8%). The youngest patient in this study was 30 days old, and the frequency of human rotavirus infection was highest at age six to eleven months.

Characterization of a virus associated with epidemic conjunctivitis in Thailand.

A strain of virus, named the A-E strain, was isolated from a patient suffering from acute haemorrhagic conjunctivitis during an epidemic of the disease in Bangkok in 1972. The virus had the characteristics of an enterovirus but was not neutralized by any known enterovirus antiserum. Cross neutralization tests indicated that the isolate was closely related to the J670-71 virus isolated in Japan. The virus produced conjunctivitis in rabbits and monkeys following conjunctival inoculation.

Inhibition of Mycoplasma pneumoniae by actinomycin D.

Growth of Mycoplasma pneumoniae was completely prevented by 0.06 mug of actinomycin D/ml, and 0.00375 mug/ml caused 90% inhibition. It thus appears that M. pneumoniae is more susceptible to actinomycin D than previously reported. Low concentrations (0.019 mug/ml) of the antibiotic primarily inhibited ribonucleic acid synthesis and high concentrations (20 mug/ml) inhibited both ribonucleic and deoxyribonucleic acid synthesis.