Serum samples were obtained within 3 days of capture from 106 cynomolgus monkeys (Macaca fascicularis) in peninsular Malaysia. Fifty-two monkeys were trapped on the fringes of palm oil estates and 54 in dense primary jungle. Sera were tested for antibodies to hepatitis A virus (HAV) with a commercial radioimmunoassay. Twenty-four animals had detectable serum anti-HAV activity (6 of 52 from palm oil estate sites and 18 of 54 from primary jungle sites). Among monkeys at both sites, antibody prevalence was strongly correlated with animal weight: overall only four of 69 monkeys (6%) weighing less than 2.0 kg had serum anti-HAV antibodies, while 14 of 29 (48%) weighing 2.0 to 3.9 kg, and 6 of 8 (75%) weighing 4.0 kg or more, had serum anti-HAV antibodies. These data suggest that wild cynomolgus monkeys in Malaysian jungles become infected with HAV or an HAV-like virus at a rate comparable to that of humans in the same region, and raise the possibility of a sylvatic cycle for HAV.
Scrub typhus is a major cause of febrile illness throughout the Asia-Pacific region. It is commonly undiagnosed, partly because of the lack of a simple, reliable diagnostic test which can be used in clinical laboratories. The indirect immunoperoxidase technique, configured into a test kit, was provided to technicians who were trained in its use. They used the kit during a 2 year field trial in their respective clinical hospital laboratories throughout Malaysia. In an evaluation using 1,722 consecutive sera tested in those laboratories, the kit was found to have a median sensitivity for IgG detection of 0.85 (range 0.33-0.95), a median specificity of 0.94 (range 0.88-1.00), reproducibility of 0.86, and efficiency of 0.92 when compared to the reference laboratory. In a proficiency survey in which 10 laboratories received 3 coded test samples, all but 2 laboratories had results within 1 dilution of the reference laboratory in quantitating specific IgG, whereas 7 laboratories were within 1 dilution in quantitating IgM. The shelf life of the kit was at least 1 year at 4 degrees C.
Congenital malaria from Malaysia is reported here for the first time. It occurred in a baby boy born to a 16-year-old primigravida who contracted Plasmodium falciparum infection during pregnancy. She suffered malaria during the later stages of pregnancy and at parturition. The placenta was heavily infested with various asexual stages of P. falciparum. Gametocytes were not seen. Extensive search did not show other species. Cord blood showed very light infection with young trophozoites of P. falciparum. Serological studies using IFA technique showed specific IgG and IgM antibodies to P. falciparum in maternal cord and two early neonatal sera. These serum samples showed lower levels of IgG antibodies against P. vivax and P. malariae, but there were no specific IgM antibodies against these species. The value of specific IgM antibody in the diagnosis of congenital malaria is discussed.
Systemic lupus erythematosus (SLE) is highly prevalent in Malaysia, which has a mixed population of Malays, Chinese, and Indians. A quantitative enzyme linked immunosorbent assay (ELISA) was used to determine anticardiolipin antibody (aCL) levels (total immunoglobulin, IgG, and IgM) in 200 patients with SLE (164 Chinese, 26 Malay, and 10 Indian) attending the University Hospital of Kuala Lumpur, Malaysia, and 103 matched controls. Only 33 (16.5%) of the patients had raised aCL levels; 26 had raised IgG aCL, five IgM aCL, and two both IgG and IgM aCL. There was a low prevalence of raised levels of aCL in the population studied, which was seen in conjunction with a rare occurrence of thrombosis. The classical association of high aCL levels with thrombocytopenia and recurrent abortions was noted, though not with cerebral disease. The low prevalence of aCL in this study population of mixed racial origin contrasts with findings in European patients with SLE and lends support to the influence of local factors, be they genetic or environmental, on the clinical manifestations of this disease.
A single antigen indirect immunofluorescence test was used to screen for chlamydial antibody among Malaysian infants, children, sexually active adults and prostitutes. Of 794 serum samples tested, 361 (45.5%) were positive. Seropositivity increased with age and sexual activity and ranged from 10 to 16% among children under 10 years old to 94.4% among prostitutes. Pregnant women and female adolescents showed a higher antibody prevalence than nonpregnant and older women. Six (13%) infants under 6 months of age were positive for chlamydial IgM.
The first stage in Peyer's patch development in the fetal lamb is characterized by the colonization of the rudimentary Peyer's patches by precursor cells expressing the IgM surface receptor. In the fetal lamb, the spleen has been implicated as the source of gene-rearranged IgM(+) B lymphocytes. This study was intended to quantitate IgM(+) lymphocytes in the spleen, lymph nodes and liver of fetal lambs at various gestational ages between 63 and 110 days using flow cytometry. Flow-cytometric analysis revealed that IgM(+) lymphocytes were rare in the liver being consistently less than 1% at every gestational age examined. IgM(+) lymphocytes were detected in the spleen (mean 9.18%) and prescapular lymph nodes (mean 11.89%) as early as 63 days. In both spleen and lymph nodes, the highest representation of IgM(+) lymphocytes occurred between 70 and 86 days gestation. The highest mean percentage of IgM(+) lymphocytes was observed in the spleen (22.63%) and lymph nodes (17.02%) at 75 days gestation. From 98 days onwards, B-lymphocyte density gradually decreased in both spleen and prescapular lymph nodes. This study indicates that substantial populations of IgM(+) lymphocytes were present in both the spleen and prescapular lymph nodes from 70 days gestation and implies that both of these locations could be potential sources for the normal colonization of the ileal Peyer's patches.
Low molecular weight IgM (LMW IgM) is the monomeric subunit of the naturally occurring pentameric IgM. It is not seen in health but has been previously observed in systemic lupus erythematosus (SLE) particularly in those patients with active disease and may reflect an adverse prognostic finding. We have therefore studied the presence of LMW IgM in 33 Chinese or Malay SLE patients (Singapore) and 21 Caucasian patients (Adelaide). LMW IgM was measured using filtration chromatography or by a sensitive immunoblotting technique. LMW IgM was observed in all patients in the Adelaide group and in 32 patients in the Singapore group with slightly greater quantities being seen in the Adelaide group. LMW IgM constituted up to 15.3% of the total IgM and was frequently associated with the presence of other low molecular weight IgM oligomers. In both groups LMW IgM correlated significantly with the total IgM levels (P less than 0.01). In a more detailed study in the Singapore group LMW IgM also correlated significantly with the IgM anticardiolipin levels (P = 0.02) but not with IgG anticardiolipin or with IgG or IgM anti-DNA levels or with rheumatoid factor. Patients with more extensive organ involvement had higher levels of LMW IgM but not at a significant level. We conclude that circulating LMW IgM occurs almost universally in SLE, is closely related to the total IgM levels and appears independent of ethnic background. The significance of LMW IgM in this disorder is unclear.
The pattern of seroconversion to Epstein-Barr virus (EBV) was determined in 98 Malaysian children aged 2 weeks to 12 years. Maternal IgG antibodies to EBV viral capsid antigen, ranging between 1:10 to 1:160 titer, were found in 70.6 percent of infants less than three months old, and dropped to 26 percent by seven to nine months. Primary infection, as denoted by emergence of EBV-IgM antibody, occurred at 4 to 6 months, and by eight years all children were seropositive. Maternal antibody titers to EBV nuclear antigen were detected in 52.9 percent of infants less than 3 months old, declined to undetectable levels by 4 to 12 months, and then increased to 40 percent by the age of 12 years. The IgA antibody to viral capsid antigen was absent in all but one infant aged one year; the child also had IgG anti-early antigen, The IgG antibody to EBV early antigen were present in 17.7 percent of the infants aged 3 months or less. This seroconversion to EBV in early life explains the absence of infectious mononucleosis in the Malaysian population. The data suggest that a subunit vaccine to protect against EBV-associated diseases, most notably nasopharyngeal carcinoma, commonly observed in Malaysians would have to be administered to infants 6-12 months of age.
Surface plasmon resonance (SPR) sensing is recently emerging as a valuable technique for measuring the binding constants, association and dissociation rate constants, and stoichimetry for a binding interaction kinetics in a number of emerging biological areas. This technique can be applied to the study of immune system diseases in order to contribute to improved understanding and evaluation of binding parameters for a variety of interactions between antigens and antibodies biochemically and clinically. Since the binding constants determination of an anti-protein dengue antibody (Ab) to a protein dengue antigen (Ag) is mostly complicated, the SPR technique aids a determination of binding parameters directly for a variety of particular dengue Ag_Ab interactions in the real-time. The study highlights the doctrine of real-time dengue Ag_Ab interaction kinetics as well as to determine the binding parameters that is performed with SPR technique. In addition, this article presents a precise prediction as a reference curve for determination of dengue sample concentration.
Accurate laboratory testing is a critical component of dengue surveillance and control. The objective of this programme was to assess dengue diagnostic proficiency among national-level public health laboratories in the World Health Organization (WHO) Western Pacific Region.
The objective of this study was to investigate the longevity of positive dot enzyme immunosorbent assay (dot EIA) results for IgM and IgG to a Salmonella typhi outer membrane protein in Malaysian children with enteric fever. The patients were children one month to 12 years of age with clinical evidence of typhoid fever, positive blood or stool cultures for S. typhi, and/or a positive Widal test result who were admitted over a two-year period to General Hospital (Kota Bharu, Malaysia). These patients received standard inpatient treatment for enteric fever including chloramphenicol therapy for 14 days. Dot EIA tests were performed as part of clinical and laboratory assessments on admission, at two weeks, and then at 3, 6, 9, 12, 15, 18, and 21 months postdischarge. Assessment of the longevity of positive dot EIA IgM and IgG titers was done by Kaplan-Meier analysis. In 94 evaluable patients, 28% were dot EIA IgM positive but IgG negative on admission, 50% were both IgM and IgG positive, and 22% were IgM negative and IgG positive. Mean persistence of IgM dot EIA positivity was 2.6 months (95% confidence interval = 2.0-3.1 months) and that of IgG was 5.4 months (4.5-6.3 months). There were no significant differences between the three subgroups. Thus, positive IgM and IgG results determined by dot EIA within four and seven months, respectively, following documented or suspected enteric fever in a child from an endemic area should be interpreted with caution. In other clinical situations, the dot EIA remains a rapid and reliable aid to diagnosis.