Prevalence of congenital cytomegalovirus and Toxoplasma antibodies in Thailand.

Prevalence of CMV and toxoplasmosis antibodies were determined among normal newborn infants, suspected congenital neonates and pregnant women. Seropositive rates of CMV and toxoplasmosis were similar. Most of the pregnant women had CMV antibodies. The in-house ELISA for detection of Toxoplasma antibodies was developed and compared with the commercial kit with sensitivity and specificity of 90.47% and 96.74% respectively.

Prevalence of cytomegalovirus in Thai blood donors by monoclonal staining of blood leukocytes.

Four hundred and forty-one blood and serum samples were collected during August to October 1998 from the blood donors at the blood bank of Rajvithi Hospital, Bangkok, Thailand. Their ages were varied between 18-55 years. All specimens were tested by immunostaining and ELISA methods. Forty-seven specimens (10.66%) gave positive results by immunostaining. Among these, 20 cases were seropositive and 27 cases were seronegative. The age group between 41-50 years had a high percentage of CMV infection as judged by the immunostaining method, more than the other age groups. By ELISA, 231 cases (52.38%) had positive IgG antibody to CMV, 42 cases (9.52%) were IgM antibody positive and 39 cases (8.84%) were positive for both IgG and IgM antibodies. The age groups between 36-40 years had a higher percentage of IgM antibody positives than the other age groups. Since the immunostaining method can detect early CMV infection, screening for the presence of antibodies alone is not enough to rule out CMV infection. Immunostaining along with ELISA detection of antibodies was useful for determining a decrease in CMV infection.

Rapid diagnosis of cytomegalovirus infection in congenital neonates.

Immunostaining was compared with PCR for diagnosis of congenital CMV infection. IgM and IgG antibody assays were also performed in parallel. Immunostaining gave sensitivity and specificity of 60% and 97% respectively. Correlations among immunostaining, PCR and the presence of IgM antibody was reported. Immunostaining can be used for early diagnosis of congenital CMV infection in parallel with detection of IgM antibody.

Prevalence of cytomegalovirus antibodies among various age groups of Thai population.

The prevalence of CMV antibody in various groups of Thai population was studied. Pregnant women and young children had been infected with CMV more than the other studied groups. Children of both sex had equal chance of getting CMV infection while the risk of CMV infection in adult between male and female was significantly difference (p < 0.001). Pregnant women had higher chance to get CMV infection than normal women. Prevalence of CMV antibody at present was similar to previous studies.

Subgroup determination of respiratory syncytial virus by RT-PCR.

PCR optimization for differentiation of RSV subgroup A (RT-PCR-1) and RSV subgroup B (RT-PCR-2) were developed. Various conditions of RT-PCR-1 and RT-PCR-2 were summarized. These methods are highly specific and sensitive to differentiate RSV subgroup A and RSV subgroup B from the other respiratory viruses.

The significance of HER-2/neu/c-erbB-2 gene amplification in benign and malignant breast disease.

This study was carried out to investigate the amplification of HER-2/neu oncogene in 66 patients with primary breast cancer and 90 samples from benign breast disease (BBD). The amplification of HER-2/neu oncogene in the DNA of paraffin-embedded specimens was determined by differential PCR. Nineteen out of 66 (28.8%) breast cancer patients showed amplification of the gene. No gene amplification was found in benign breast disease. There was no significant correlation of HER-2/neu amplification with, age, menopausal status, the number of positive nodes, tumor size, estrogen receptor, however, amplification of HER-2/neu gene was strongly correlated with nodal status (p = 0.0049). In node positive patients, the incidence of HER-2/neu amplification was high (43%). These findings indicate that the amplification of HER-2/neu gene may be of pathogenetic significance in breast cancer and may have a poor prognosis in node positive breast cancer patients while no gene amplification in benign breast disease suggests that HER-2/neu amplification is a late molecular alteration event in the pathogenesis of breast cancer.

Simplified, rapid diagnosis of respiratory syncytial virus from clinical specimens.

DOT ELISA was compared with RT-PCR and tissue culture to detect RSV from nasopharyngeal aspirates. DOT ELISA had diagnostic sensitivity and specificity of 65.62% and 93.92%, respectively. The results indicate that DOT ELISA can be used for screening detection of RSV from clinical specimens and is suitable for small laboratories in the provincial areas of developing countries.

Monoclonal antibodies against respiratory syncytial virus for rapid detection and subgroup determination.

Thirty-one hybridomas producing monoclonal antibodies (MAbs) against structural proteins of RSV subgroup A (Long strain) and RSV subgroup B (Japanese wild strain) were produced and separated into three groups by their reactivities with RSV-A and RSV-B using IFA. Group I was specific to RSV-A, Group II was specific to RSV-B and group III was specific to both subgroups. Characterization of selected two MAbs from each group indicated that three MAbs recognized phosphoprotein (P) and the others recognized fusion protein (F). All of the selected MAbs were IgG1 and carried kappa light chain. These selected MAbs can be used to detect the presence of RSV from NPAs and classify them into two subgroups. The infection rates of RSV in Thai children are very low and most of them were RSV subgroup A.

Detection of respiratory syncytial virus from clinical specimens: comparison between reverse transcription polymerase chain reaction and tissue culture.

RT-PCR was compared with tissue culture to detect RSV from nasopharyngeal aspirates. RT-PCR was more sensitive and specific than tissue culture method. RT-PCR has sensitivity and specificity of 100% and 97%, respectively. The results indicate that RT-PCR can be used for detection of RSV in clinical specimens.

Hantaanvirus among urban rats from a slum area in Bangkok.

A total of 106 rodents sera from slum Wat Phai Ton and slum Klong Toey were examined by immunofluorescent antibody assay during May to August 1990. The positive sera were further tested by plaque reduction neutralization test with the prototype hantaanvirus and the rat-associated hantaan like virus. Isolation attempts were also performed from their tissues. Antibody-positive rats were found in both slum areas, 32.7% in slum Wat Phai Ton and 5.6% in slum Klong Toey. Rattus norvegicus was the major species found positive. Positive plaque reduction neutralization results indicated that the infecting virus was antigenically similar to the strain of rat-associated hantaanvirus. The presence of low titer antibodies (IFA titer 32 to 128) may be an obstacle to isolation of associated virus using tissue culture.

Cross-sectional seroepidemiological survey of malaria in endemic areas with different activities of malaria control.

A single cross-sectional seroepidemiological survey of malaria antibody was conducted in 1982 in Klang District, Rayong Province in three villages under different phases of malaria control activity to determine whether a single survey could be used to delineate malaria endemicity in Thailand and to compare the usefulness of ELISA and the indirect haemagglutination test (IHA) in the assessment of malaria endemicity. Village 11 was a control area with high infection rate with an annual slide positive rate of 16.3% in 1981. Village 6 was also a control area but was in the late attack phase in which residual insecticide spraying has been ceased since 1976. Village 7 was a consolidation area. Finger-tipped blood was collected from 189, 191 and 132 individuals from villages 11, 6 and 7 respectively, and the plasma tested for anti-P. falciparum antibody with ELISA and IHA. With ELISA, it was shown that the seropositive rate in population of village 11 (84.6%) was significantly higher than those of other two villages (48.9% in village 6 and 28.8% in village 7). After age stratification, it was shown that the differences were observed in every age group except in the greater than or equal to 45 year age group of village 6. With IHA, a significantly higher seropositive rates in population of village 11 was evident when they were compared with the corresponding age groups of 6-14, 15-29 and 30-44 years in village 7, and the age group of less than or equal to 5 year in village 6.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibody responses to heat-killed, phenol preserved parenteral typhoid vaccine.

The heat-killed, phenolized parenteral typhoid vaccine was tested in informed volunteers. Assessment for its immunogenicity was performed using Widal test and enzyme-linked immunosorbent assay (ELISA). The anti-H antibody, which is a marker of the vaccine antigenicity peaked at one month after the vaccination and appeared throughout the one year course of the study. The anti-O antibody peaked at 7th day after vaccination and lasted only for 6 months. Classes of specific antibodies were determined by ELISA using single extracted lipopolysaccharide from Salmonella typhi 0901 as antigen. The possible protective role of serum derived intestinal IgG and IgA were discussed. Based on the agglutinating antibodies, the results indicate that the heat-killed, phenolized typhoid vaccine conferred at least 6 months protective period.

A simple and rapid diagnostic test for typhoid fever.

Barber protein sensitized latex particles were used in the latex agglutination test for the diagnosis of typhoid fever and the result compared with that of Widal 'O' and 'H' agglutination test. The latex agglutination test was positive in all 20 bacteriologically proved typhoid patients, in 81 of 85 (95.3%) typhoid suspected patients, and only in 2 of 85 (2.3%) blood donors. In contrast, the positive rates were 60% for both 'O' and 'H' Widal agglutinations in bacteriologically proved typhoid patients, 34.2% and 71.7% respectively in typhoid suspected patients, and none of blood donors were positive. The sensitivity and specificity of the latex agglutination test were 100% and 97.6% respectively with positive and negative predictive values of 90.9% and 100% respectively. The latex agglutination test may be particularly useful for the presumptive diagnosis of typhoid fever in remote health centres.

Infection rates of respiratory syncytial virus in pediatric patients attending Phra Mongkutklao Hospital, Bangkok.

Respiratory syncytial virus (RSV) and other pathogens were isolated from nasopharyngeal secretions from 200 pediatric patients attending the Out Patient Department of Phra Mongkutklao Hospital with symptoms of upper respiratory tract infections. Their sera were also taken for determination of class specific immunoglobulin antibody titers. The positive isolation rates were 36% for RSV, 5.5% for adenovirus 1.5% for herpes simplex virus (HSV), and 4% for Staphylococcus aureus. One to 5.5% of these patients had mixed infection. Ninety five percent of patients with positive RSV isolations had IgM antibody which was found only in 30.7% in patients with negative RSV isolations. This result indicated that RSV was likely to be the most common pathogen responsible for the upper respiratory tract infections in children in Bangkok during the rainy season.

Herpes simplex virus and genital infections in Thai pregnant women.

Vaginal swabs were collected monthly from 100 asymptomatic Thai pregnant women as well as from 11 pregnant women with herpetic lesions of the vulva for isolations of HVH, mycoplasma and gonorrhoea. In asymptomatic mothers, 25% and 21% of cases were positive for HVH and mycoplasma respectively. Mixed infections of HVH and mycoplasma, and HVH and gonorrhoea were also found in 27% and 1% of cases respectively. Follow-up in asymptomatic pregnant women and those with herpetic lesions showed positive HVH fluctuations throughout the course of study. Positive HVH was recovered from 48% of amniotic fluid and 32% of breast milk of asymptomatic pregnant women with positive HVH genital isolates, and in 72.7% of aminotic fluid and 36.4% of breast milk in patients with herpetic lesions. HVH was also isolated from 84% of infants of asymptomatic mothers positive for HVH, and 100% of patients with herpetic ulcer. HVH was isolated most frequently from the throat and also from nose, eyes, and ears but with less frequency. IgM antibodies were found in three infants born of asymptomatic mother and in one infant of a mother with herpetic lesion. The low percentage of IgM antibody was interpreted to mean that the HVH isolated from the newborn infants were acquired during passage through the birth canal.

Infection rates of Cytomegalovirus among Thai pregnant women.

Cervical swabs were collected from 185 pregnant women and urine from 50 healthy non-pregnant women in order to isolate cytomegalovirus by using tissue culture methods. Sera from the mothers and their cord blood were tested for total and classes specific IgM antibodies to cytomegalovirus by using enzyme-linked immunosorbent assay test. CMV was recovered from 8% of pregnant women but none from the non-pregnant women. Seropositive rate for CMV total antibodies and IgM antibodies in pregnant women were 95% and 83% respectively. None of the newborn infants from virus positive mothers had positive CMV-IgM antibodies but one infant from virus-negative mother had IgM antibodies with titre 1:80.

Comparison of various serological test results using antigens from different strains of Plasmodium falciparum.

Suitability of different strains of Plasmodium falciparum grown continuously in vitro was compared using the indirect haemagglutination (IHA) the indirect immunofluorescent (IFA) tests and ELISA. In the tests employing soluble antigens (IHA and ELISA), there was a significant higher mean log titer of the same sera tested against different strains. Ranking of the strains in term of sensitivity for the detection of malaria antibody in people in the endemic area were G-112 = SO = CC greater than SU greater than PS in the IHA test and G-112 = SO greater than CC greater than SU greater than PS in the ELISA. The difference in the mean log titers appear to relate neither to the geographical location not the isoenzyme markers tested. There was also an apparent correlation between the results of the IHA and the IFA test but not between these two tests and ELISA.