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.     

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.     

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.     

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.     

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.     

Coxsackie group B virus and primary myocardial disease in infants and children

Eighteen infants and children with the clinical diagnosis of primary myocardial disease are reported. Of those cases who had serologic study for coxsackie B performed, 42 per cent were found to indicate a recent infection. The data was reported according to its outcome. Possible relationships between viral myocarditis and EFE are discussed.     

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.