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Fulltext Leptospirosis in Kuala Lumpur and the comparative evaluation of two rapid commercial diagnostic kits against the MAT test for the detection of antibodies to leptospira interrogans

Sekhar WY, Soo EH, Gopalakrishnan V, Devi S

Singapore Med J, 2000 Aug;41(8):370-5.
PMID: 11256343

The aim of the study was to look into the epidemiology of serodiagnosed cases of leptospirosis at the University Hospital and compare two commercial ELISA Assays to the Microscopic Agglutination Test (MAT). Demographic data for all serodiagnosed cases for the years 1991-1997 were collected. From this data, 104 sera (n = 104) were selected as samples for comparative evaluation of the commercial ELISAs (INDX Dip-S-Ticks and PanBio ELISA) to the MAT test. Thirty two (n = 32) negative control sera were selected from serodiagnosed cases of other differential diagnosis of leptospira infection. The MAT test is a standard test that detects agglutination antibodies to leptospira biflexa, while the INDX Dip-S-Ticks is an ELISA dot test assaying for total anti-leptospira antibodies. The PanBio ELISA is a colorometric assay in test well strips to detect anti-leptospira IgM. The sensitivity, specificity, and efficiency of tests were calculated at a MAT cut-off value of 1:320. Demographic data showed that leptospirosis peaks during March-May and Aug-Nov coinciding with the inter-monsoon period with more men being infected than women and more adults than children. The sensitivity, specificity, and efficiency of test for the INDX Dip-S-Ticks were 83.3%, 93.8% and 87.5% while the values for the PanBio ELISA were 54.2%, 96.9% and 71.3%. The suboptimal PanBio result could be related to the blocking effect of high IgG titres or could be related to the diagnostic MAT cut-off values used in this study. The data hence reflects a pattern of transmission that is related to "wet" occupational risk factors. The commercial assays evaluated, are easier to perform but interpretation of results should be based on level of endemicity. The INDX Dip-S-Ticks allows this flexibility and is a practical alternative to the MAT test.

Matched MeSH terms: Immunoglobulin M/blood*
Fulltext Japanese encephalitis virus is an important cause of encephalitis among children in Penang

Cardosa MJ, Hooi TP, Kaur P

Southeast Asian J. Trop. Med. Public Health, 1995 Jun;26(2):272-5.
PMID: 8629059

This study was carried out to determine if Japanese encephalitis virus is an important causative agent of viral encephalitis among pediatric admissions in Penang, Malaysia. 195 children with CNS symptoms and 482 children with non-specific febrile illness admitted into the Pediatric Ward of Penang Hospital during a 16 month period were entered into the study. The presence in serum of cerebrospinal fluid (csf) of Japanese encephalitis virus (JEV) specific IgM was determined by an IgM capture ELISA and cytomegalovirus (CMV) specific IgM was determined using a commercially available kit (Behringwerke AG). It was determined that 5 of 13 children with a discharge diagnosis of viral encephalitis had JEV specific IgM in csf, indicating that 38.5% of the viral encephalitis cases was due to JEV. One of the non-JEV cases was found to have mumps virus specific IgM in csf, while no etiology was determined for the other cases. It was also determined that 4 of the 195 (2.1%) cases with CNS symptoms had IgM to CMV, suggesting CMV may be an agent of encephalopathy in children in Penang. Other viruses found to be associated with CNS symptoms in children admitted into our study were measles and herpes simplex virus. A viral etiology was confirmed for 13 or the 195 cases (6.7%). We also screened 482 non-specific febrile cases for IgM to JEV and to dengue viruses and found that 2 (0.4%) had IgM specific for JEV and 9 (1.9%) had IgM specific for dengue virus.

Matched MeSH terms: Immunoglobulin M/blood
Induction of suppressor cells following mucosal presentation of Actinomyces viscosus in mice

Sosroseno W, Bird PS, Gemmell E, Seymour GJ

Oral Microbiol. Immunol., 2003 Oct;18(5):318-22.
PMID: 12930525

Mucosal presentation of Actinomyces viscosus results in antigen-specific systemic immune suppression, known as oral tolerance. The aim of the present study was to determine the mechanism by which this oral tolerance is induced. DBA/2 mice were gastrically immunized with A. viscosus. Serum, Peyer's patch (PP) and spleen cells were transferred to syngeneic recipients which were then systemically challenged with the sameiA. viscosus strain. To determine antigen-specificity of cells from gastrically immunized mice, recipients which received immune spleen cells were also challenged with Porphyromonas gingivalis. One week after the last systemic challenge, the delayed type hypersensitivity (DTH) response was determined by footpad swelling and the level of serum IgG, IgA and IgM antibodies to A. viscosus or P. gingivalis measured by an ELISA. No suppression of DTH response or of specific serum antibodies was found in recipients which received serum from gastrically immunized mice. Systemic immune suppression to A. viscosus was observed in recipients which had been transferred with PP cells obtained 2 days but not 4 and 6 days after gastric immunization with A. viscosus. Conversely, suppressed immune response could be seen in recipients transferred with spleen cells obtained 6 days after gastric immunization. The immune response to P. gingivalis remained unaltered in mice transferred with A. viscosus-gastrically immunized cells. The results of the present study suggest that oral tolerance induced by A. viscosus may be mediated by antigen-specific suppressor cells which originate in the PP and then migrate to the spleen.

Matched MeSH terms: Immunoglobulin M/blood
Fulltext Induction and Kinetics of Complement-Fixing Antibodies Against Plasmodium vivax Merozoite Surface Protein 3α and Relationship With Immunoglobulin G Subclasses and Immunoglobulin M

Oyong DA, Wilson DW, Barber BE, William T, Jiang J, Galinski MR, et al.

J Infect Dis, 2019 11 06;220(12):1950-1961.
PMID: 31419296 DOI: 10.1093/infdis/jiz407

BACKGROUND: Complement-fixing antibodies are important mediators of protection against Plasmodium falciparum malaria. However, complement-fixing antibodies remain uncharacterized for Plasmodium vivax malaria. P. vivax merozoite surface protein 3α (PvMSP3α) is a target of acquired immunity and a potential vaccine candidate.
METHODS: Plasma from children and adults with P. vivax malaria in Sabah, Malaysia, were collected during acute infection, 7 and 28 days after drug treatment. Complement-fixing antibodies and immunoglobulin M and G (IgM and IgG), targeting 3 distinctive regions of PvMSP3α, were measured by means of enzyme-linked immunosorbent assay.
RESULTS: The seroprevalence of complement-fixing antibodies was highest against the PvMSP3α central region (77.6%). IgG1, IgG3, and IgM were significantly correlated with C1q fixation, and both purified IgG and IgM were capable of mediating C1q fixation to PvMSP3α. Complement-fixing antibody levels were similar between age groups, but IgM was predominant in children and IgG3 more prevalent in adults. Levels of functional antibodies increased after acute infection through 7 days after treatment but rapidly waned by day 28.
CONCLUSION: Our study demonstrates that PvMSP3α antibodies acquired during P. vivax infection can mediate complement fixation and shows the important influence of age in shaping these specific antibody responses. Further studies are warranted to understand the role of these functional antibodies in protective immunity against P. vivax malaria.

Matched MeSH terms: Immunoglobulin M/blood
Fulltext In-house ELISA screening using a locally-isolated Leptospira in Malaysia: determination of its cut-off points

Tan XT, Amran F, Chee Cheong K, Ahmad N

BMC Infect Dis, 2014;14:563.
PMID: 25338815 DOI: 10.1186/s12879-014-0563-7

Leptospirosis is a zoonotic disease caused by Leptospira species and is distributed globally. Microscopic agglutination test (MAT) is the serological 'gold standard' for diagnosis of leptospirosis but it is time-consuming and labour-intensive. An alternative serological method that is rapid, sensitive and specific is important for early treatment to reduce morbidity and mortality. The use of local Leptospira isolation may improve the sensitivity and specificity of the test because it may varies from one geographical region to another region. The objective of this study was to determine the sensitivity, specificity and cut-off points for an in-house Immunoglobulin M (IgM) enzyme-linked immunosorbent assay (ELISA) using a locally isolated Leptospiral strain IMR/175 as the antigen for the detection of anti-Leptospiral IgM.

Matched MeSH terms: Immunoglobulin M/blood
Fulltext Impact of a measles elimination strategy on measles incidence in Malaysia

Saraswathy TS, Zahrin HN, Norhashmimi H, Az-Ulhusna A, Zainah S, Rohani J

Southeast Asian J. Trop. Med. Public Health, 2009 Jul;40(4):742-7.
PMID: 19842408

In Malaysia, the two dose measles - mumps - rubella (MMR) vaccine was introduced in the Expanded Program on Immunization in 2002. The Ministry of Health then initiated a measles elimination strategy which included enhanced case-based surveillance with laboratory testing of all suspected cases. The objective of our study was to analyse national measles laboratory data from 2004 to 2008 to study the impact of the nationwide strategy on measles case incidence. Blood samples collected from suspected measles cases during the acute stage of the illness were investigated for measles specific IgM. The estimated incidence of measles ranged from 22.3 cases (in 2004) to 2.27 cases (in 2006) per 100,000 population. During this time, the measles vaccination coverage was above 85%. Laboratory confirmed measles cases dropped from 42.2% in 2004, when sporadic outbreaks were reported, to 3.9% in 2007. Screening for measles IgG levels in 2008 showed that 82.8% of those > 7 years old had adequate immunity. The measles control strategy appears to have been successful in reducing the incidence of measles. Continuing high vaccination coverage rates and ongoing measles surveillance are necessary to achieve our goal of measles elimination.

Matched MeSH terms: Immunoglobulin M/blood
Immunogenic characterization of the chimeric surface antigen 1 and 2 (SAG1/2) of Toxoplasma gondii expressed in the yeast Pichia pastoris

Lau YL, Thiruvengadam G, Lee WW, Fong MY

Parasitol Res, 2011 Sep;109(3):871-8.
PMID: 21455621 DOI: 10.1007/s00436-011-2315-6

In this study, we successfully expressed a chimerical surface antigen 1 and 2 (SAG1/2) of Toxoplasma gondii in Pichia pastoris. Eighty human serum samples, including 60 from confirmed cases of toxoplasmosis, were tested against the purified recombinant SAG1/2 in Western blots. Results of Western blots targeted at Toxoplasma IgG and IgM showed that the recombinant SAG1/2 reacted with all sera from the toxoplasmosis cases but none with the Toxoplasma-negative serum samples. These results showed that the P. pastoris-derived recombinant SAG1/2 was sensitive and specific and suitable for use as antigen for detecting anti-Toxoplasma antibodies. To further investigate the immunological characteristic of the recombinant protein, the recombinant SAG1/2 was injected subcutaneously into BALB/c mice, and their serum was tested against total protein lysate of T. gondii. Mice immunized with the recombinant SAG1/2 reacted specifically with the native SAG1 and SAG2 of T. gondii. Significant proliferation of splenocytes stimulated with tachyzoite total protein lysate was observed in vaccinated BALB/c mice but not in those from negative control mice. Specific production of IFN-γ, the Th1-type cytokines, was also found in stimulated splenocytes from vaccinated mice. These results show that the chimeric protein recombinant SAG1/2 can elicit a Th1-associated protection against T. gondii infections in mice. Finally, vaccinated mice were significantly protected against lethal challenge with live T. gondii RH strain tachyzoites (P

Matched MeSH terms: Immunoglobulin M/blood
Fulltext Immune response in acute Toxoplasma infection of Balb/C, ICR and CBA/J mice

Suresh K, Mak JW, Yong HS

Southeast Asian J. Trop. Med. Public Health, 1991 Sep;22(3):452-4.
PMID: 1818401
Matched MeSH terms: Immunoglobulin M/blood
Fulltext IgM capture ELISA for detection of IgM antibodies to dengue virus: comparison of 2 formats using hemagglutinins and cell culture derived antigens

Cardosa MJ, Tio PH, Nimmannitya S, Nisalak A, Innis B

Southeast Asian J. Trop. Med. Public Health, 1992 Dec;23(4):726-9.
PMID: 1298081

The highly sensitive AFRIMS format IgM capture ELISA for the diagnosis of dengue virus infections requires the use of mouse brain derived hemagglutinins and consequently also the use of 20% acetone extracted normal human serum to eliminate high background. These reagents are not always easily available and we have thus compared the AFRIMS format with another published format which uses cell culture derived antigens (culture fluid, CF, format) in order to determine if it is reasonable to use cell culture derived antigens in situations where hemagglutinins and normal human serum are difficult to obtain. The study shows that using AFRIMS results as the reference point, the CF format described here has a sensitivity of 90% and a specificity of 96%.

Matched MeSH terms: Immunoglobulin M/blood*
Fulltext IgG avidity assay: a tool for excluding acute toxoplasmosis in prolonged IgM titer sera from pregnant women

Emelia O, Rahana AR, Mohamad Firdaus A, Cheng HS, Nursyairah MS, Fatinah AS, et al.

Trop Biomed, 2014 Dec;31(4):633-40.
PMID: 25776588 MyJurnal

An accurate diagnosis for toxoplasmosis is crucial for pregnant women as this infection may lead to severe sequelae in the fetus. The value of IgG avidity assay as a tool to determine acute and chronic toxoplasmosis during pregnancy was evaluated in Universiti Kebangsaan Malaysia Medical Centre (UKMMC). In this study, 281 serum samples from 281 pregnant women in various trimesters were collected. These samples were assayed using specific anti-Toxoplasma IgM and IgG antibodies, followed by IgG avidity test. The overall seroprevalence of toxoplasmosis in pregnant women was 35.2% (33.5% for anti-Toxoplasma IgG and 1.8% for both anti-Toxoplasma IgG and IgM antibodies). Of 5 (1.8%) serum samples positive for IgM ELISA, 4 had high-avidity antibodies, suggesting past infection and one sample with borderline avidity index. Two samples with low avidity were from IgM negative serum samples. The IgG avidity assay exhibited an excellent specificity of 97.6% and a negative predictive value (NPV) of 95.6%. The study also demonstrated no significant correlation between avidity indexes of the sera with IgG (r=0.12, p=0.24) and IgM (r=-0.00, p=0.98), suggesting the complementary needs of the two tests for a better diagnosis outcome. These findings highlight the usefulness of IgG avidity assay in excluding a recently acquired toxoplasmosis infection in IgM-positive serum sample.

Matched MeSH terms: Immunoglobulin M/blood*
Fulltext Identification and real-time expression analysis of selected Toxoplasma gondii in-vivo induced antigens recognized by IgG and IgM in sera of acute toxoplasmosis patients

Amerizadeh A, Khoo BY, Teh AY, Golkar M, Abdul Karim IZ, Osman S, et al.

BMC Infect Dis, 2013;13:287.
PMID: 23800344 DOI: 10.1186/1471-2334-13-287

Toxoplasma gondii is an obligate intracellular zoonotic parasite of the phylum Apicomplexa which infects a wide range of warm-blooded animals, including humans. In this study in-vivo induced antigens of this parasite was investigated using in-vivo induced antigen technology (IVIAT) and pooled sera from patients with serological evidence of acute infection.

Matched MeSH terms: Immunoglobulin M/blood
Genotyping and characterization of Toxoplasma gondii strain isolated from pigs in Hubei province, central China

Xia NB, Lu Y, Zhao PF, Wang CF, Li YY, Tan L, et al.

Trop Biomed, 2020 Jun 01;37(2):489-498.
PMID: 33612818

Toxoplasma gondii, a ubiquitous pathogen that infects nearly all warm-blooded animals and humans, can cause severe complications to the infected people and animals as well as serious economic losses and social problems. Here, one local strain (TgPIG-WH1) was isolated from an aborted pig fetus, and the genotype of this strain was identified as ToxoDB #3 by the PCR RFLP typing method using 10 molecular markers (SAG1, SAG2, alternative SAG2, SAG3, BTUB, GRA6, L358, PK1, C22-8, C29-2 and Apico). A comparison of the virulence of this isolate with other strains in both mice and piglets showed that TgPIG-WH1 was less virulent than type 1 strain RH and type 2 strain ME49 in mice, and caused similar symptoms to those of ME49 such as fever in piglets. Additionally, in piglet infection with both strains, the TgPIG-WH1 caused a higher IgG response and more severe pathological damages than ME49. Furthermore, TgPIG-WH1 caused one death in the 5 infected piglets, whereas ME49 did not, suggesting the higher virulence of TgPIG-WH1 than ME49 during piglet infection. Experimental infections indicate that the virulence of TgPIG-WH1 relative to ME49 is weaker in mice, but higher in pigs. This is probably the first report regarding a ToxoDB #3 strain from pigs in Hubei, China. These data will facilitate the understanding of genetic diversity of Toxoplasma strains in China as well as the prevention and control of porcine toxoplasmosis in the local region.

Matched MeSH terms: Immunoglobulin M/blood
Fulltext Evaluation of commercially available diagnostic tests for the detection of dengue virus NS1 antigen and anti-dengue virus IgM antibody

Hunsperger EA, Yoksan S, Buchy P, Nguyen VC, Sekaran SD, Enria DA, et al.

PLoS Negl Trop Dis, 2014 Oct;8(10):e3171.
PMID: 25330157 DOI: 10.1371/journal.pntd.0003171

Commercially available diagnostic test kits for detection of dengue virus (DENV) non-structural protein 1 (NS1) and anti-DENV IgM were evaluated for their sensitivity and specificity and other performance characteristics by a diagnostic laboratory network developed by World Health Organization (WHO), the UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (TDR) and the Pediatric Dengue Vaccine Initiative (PDVI). Each network laboratory contributed characterized serum specimens for the panels used in the evaluation. Microplate enzyme-linked immunosorbent assay (ELISA) and rapid diagnostic test (RDT formats) were represented by the kits. Each ELISA was evaluated by 2 laboratories and RDTs were evaluated by at least 3 laboratories. The reference tests for IgM anti-DENV were laboratory developed assays produced by the Armed Forces Research Institute for Medical Science (AFRIMS) and the Centers for Disease Control and Prevention (CDC), and the NS1 reference test was reverse transcriptase polymerase chain reaction (RT-PCR). Results were analyzed to determine sensitivity, specificity, inter-laboratory and inter-reader agreement, lot-to-lot variation and ease-of-use. NS1 ELISA sensitivity was 60-75% and specificity 71-80%; NS1 RDT sensitivity was 38-71% and specificity 76-80%; the IgM anti-DENV RDTs sensitivity was 30-96%, with a specificity of 86-92%, and IgM anti-DENV ELISA sensitivity was 96-98% and specificity 78-91%. NS1 tests were generally more sensitive in specimens from the acute phase of dengue and in primary DENV infection, whereas IgM anti-DENV tests were less sensitive in secondary DENV infections. The reproducibility of the NS1 RDTs ranged from 92-99% and the IgM anti-DENV RDTs from 88-94%.

Matched MeSH terms: Immunoglobulin M/blood*
Evaluation of capture ELISA and rapid immunochromatographic test for the determination of IgM and IgG antibodies produced during dengue infection

Lam SK, Devine PL

Clin Diagn Virol, 1998 May 1;10(1):75-81.
PMID: 9646004

Rapid diagnosis of dengue infection is essential to patient management and disease control. The development of a rapid (5 min) immunochromatographic test and a 2 h commercial capture enzyme linked immunosorbent assay (ELISA) for anti-dengue IgM and IgG antibodies may lead to more rapid and accurate testing in peripheral health settings and diagnostic laboratories.

Matched MeSH terms: Immunoglobulin M/blood*
Fulltext Evaluation of a commercial SD dengue virus NS1 antigen capture enzyme-linked immunosorbent assay kit for early diagnosis of dengue virus infection

Wang SM, Sekaran SD

J Clin Microbiol, 2010 Aug;48(8):2793-7.
PMID: 20573879 DOI: 10.1128/JCM.02142-09

Early definitive diagnosis of dengue virus infection may help in the timely management of dengue virus infection. We evaluated the Standard Diagnostics (SD, South Korea) dengue virus nonstructural protein NS1 antigen enzyme-linked immunosorbent assay (SD dengue NS1 Ag ELISA) for the detection of dengue virus NS1 antigen in patients' sera, using a total of 399 serum samples in a comparison with real-time reverse transcription (RT)-PCR, an in-house IgM capture (MAC)-ELISA, and a hemagglutination inhibition (HI) assay. Of the 320 dengue sera, 205 (64%) tested positive for NS1 antigen compared to 300 (93.75%) by either MAC-ELISA or RT-PCR, 161 (50.31%) by RT-PCR, and 226 (70.36%) by MAC-ELISA only. The assay was able to detect NS1 antigen in convalescent-phase sera until day 14 of infection. The NS1 detection rate is inversely proportional while the IgM detection rate is directly proportional to the presence of IgG antibodies. The overall sensitivity and specificity of the SD dengue NS1 Ag ELISA in the detection of "confirmed dengue virus" sera are 76.76% and 98.31%, respectively. This suggests that the SD kit is highly specific and sensitive for the detection of NS1 antigen. However, caution is needed when the kit is used as a single assay, as detection in samples that contained the virus was only about 81.97%. Combining this assay with an IgM and/or IgG assay will increase the sensitivity of detection, especially in areas with a higher prevalence of secondary dengue virus infections.

Matched MeSH terms: Immunoglobulin M/blood
Evaluation of a capture screening enzyme-linked immunosorbent assay for combined determination of immunoglobulin M and G antibodies produced during Dengue infection

Kit Lam S, Lan Ew C, Mitchell JL, Cuzzubbo AJ, Devine PL

Clin Diagn Lab Immunol, 2000 Sep;7(5):850-2.
PMID: 10973469

A commercially available enzyme-linked immunosorbent assay (ELISA) (PanBio Dengue Screening ELISA) that utilized both immunoglobulin M (IgM) and IgG capture in the same microtiter well for the diagnosis of dengue infection was evaluated. Sensitivity in primary and secondary dengue was 95%, while specificity was 94%.

Matched MeSH terms: Immunoglobulin M/blood*
Fulltext Evaluation of a Commercial Immuno-Chromatographic Assay Kit for Rapid Detection of IgM Antibodies against Leptospira Antigen in Human Serum

Amran F, Liow YL, Halim NAN

J Korean Med Sci, 2018 Apr 23;33(17):e131.
PMID: 29686599 DOI: 10.3346/jkms.2018.33.e131

Leptospirosis is a febrile zoonotic disease. Routine diagnosis of leptospirosis is based on the detection of specific antibodies with serological tests. The aim of our study was to determine the usefulness of immunochromatographic assay (ICA), ImmuneMed Leptospira IgM Duo Rapid test kit from Korea, in rapid screening of acute leptospirosis in emergency cases with limited expertise. A total of 197 serum samples (93 positive, 104 negative) were selected randomly. The test has good diagnostic sensitivity 73% and specificity 90%. With positive predictive value of 87% and negative predictive value of 79%, this reassures patients have higher chance of correct diagnosis. This ICA is acceptable for screening of leptospirosis but confirmation with microscopic agglutination test should follow.

Matched MeSH terms: Immunoglobulin M/blood
Evaluation of IgM LAT and IgM ELISA as compared to microscopic agglutination test (MAT) for early diagnosis of Leptospira sp

Zin NM, Othman SN, Abd Rahman FR, Abdul Rachman AR

Trop Biomed, 2019 Dec 01;36(4):1071-1080.
PMID: 33597476

Leptospirosis is a worldwide zoonotic disease caused by spirochetes of the genus Leptospira. The clinical manifestation of leptospirosis is non-specific and frequently misdiagnosed as other illnesses. The aim of this study was to compare the diagnostic accuracies of two commercial tests for early diagnosis of Leptospira species: the IgM latex agglutination test (IgM LAT) and the IgM enzyme-linked immunosorbent assay (IgM ELISA). A total of 140 serum samples were obtained from patients suspected of leptospirosis at the Universiti Kebangsaan Malaysia Medical Centre (UKMMC). These serum samples were tested for the presence of Leptospira sp. using IgM LAT, IgM ELISA and MAT. From Table 1, IgM LAT showed 21% (n = 29) positive, 18% (n = 25) inconclusive and 61% (n = 86) negative, while IgM ELISA showed 6% (n = 8) positive, 6% (n = 8) inconclusive, 88% (n = 124) negative and MAT showed 11% (n = 16) positive, 47% (n = 65) inconclusive, 42% (n = 59) negative. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of IgM LAT were 68.8%, 57.6%, 30.6% and 87.2% respectively, while for IgM ELISA they were 37.5%, 89.8%, 50% and 84.1%, respectively as compared to MAT (Table 2). The results showed that IgM LAT had higher sensitivity but lower specificity compared to IgM ELISA. In conclusion, IgM LAT can be useful as an early screening test for early diagnosis of Leptospira sp., while IgM ELISA is a suitable method for reducing false negative detection of Leptospira sp. As both tests show moderate percentages (~65%) in accuracy, an additional test is required for better detection of Leptospira sp.

Matched MeSH terms: Immunoglobulin M/blood*
Establishment of an immunofluorescence assay to detect IgM antibodies to Nipah virus using HeLa cells expressing recombinant nucleoprotein

Kaku Y, Park ES, Noguchi A, Inoue S, Lunt R, Malbas FF, et al.

J Virol Methods, 2019 07;269:83-87.
PMID: 30954461 DOI: 10.1016/j.jviromet.2019.03.009

A novel indirect fluorescent antibody test (IFAT) for detection of IgM against Nipah virus (NiV) was developed using HeLa 229 cells expressing recombinant NiV nucleocapsid protein (NiV-N). The NiV IFAT was evaluated using three panels of sera: a) experimentally produced sera from NiV-N-immunized/pre-immunized macaques, b) post-infection human sera associated with a Nipah disease outbreak in the Philippines in 2014, and c) human sera from a non-exposed Malaysian population. Immunized macaque sera showed a characteristic granular staining pattern of the NiV-N expressed antigen in HeLa 229 cells, which was readily distinguished from negative-binding results of the pre-immunized macaque sera. The IgM antibody titers in sequential serum samples (n = 7) obtained from three Nipah patients correlated well with previously published results using conventional IgM capture ELISA and SNT serology. The 90 human serum samples from unexposed persons were unreactive by IFAT. The IFAT utilizing NiV-N-expressing HeLa 229 cells to detect IgM antibody in an early stage of NiV infection is an effective approach, which could be utilized readily in local laboratories to complement other capabilities in NiV-affected countries.

Matched MeSH terms: Immunoglobulin M/blood*
Epstein-Barr Virus Seroprevalence and Force of Infection in a Multiethnic Pediatric Cohort, Singapore

Setoh JWS, Ho CKM, Yung CF, Tam C, Yelen, Tee NWS

Pediatr Infect Dis J, 2019 12;38(12):1173-1176.
PMID: 31738332 DOI: 10.1097/INF.0000000000002484

BACKGROUND: Epstein-Barr virus (EBV) spreads through bodily fluids, especially saliva, and can cause infectious mononucleosis. EBV immunity and infection status can be assessed by testing EBV viral capsid antigen and nuclear antigen (EBNA) antibodies in blood. In this study, we investigated the seroprevalence and force of infection (FOI) of EBV antibodies among children and young people in 3 ethnic groups in Singapore.
METHODS: Eight hundred ninety-six residual serum samples at a tertiary hospital were tested for viral capsid antigen (IgG and IgM) and EBNA IgG antibodies using Abbott Architect assays. We calculated the EBV seroprevalence using catalytic models to estimate the EBV force of infection from age-stratified seroprevalence data, both overall and by ethnic group.
RESULTS: Overall seropositivity was 68.3% (n = 612). Seropositivity was higher in Malays (81.8%) compared with both Chinese (64.2%) and Indians (58.4%). EBV FOI was consistently higher in Malays, with an estimated annual rate of seroconversion of 25% in children 1 year, of age compared with 14% among Chinese and Indians at the same age.
CONCLUSIONS: The seroprevalence patterns of EBV antibodies in the Chinese and Indian, but not Malay children in Singapore by 19 years of age resemble those previously reported in developed countries. Ideally, any future EBV vaccination strategy would need to target infants <1 year of age for maximum population benefit.

Matched MeSH terms: Immunoglobulin M/blood

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