Siti Churrotin

Detection of chikungunya virus antigen by a novel rapid immunochromatographic test.

ABSTRACT Chikungunya fever is a mosquito-borne disease of key public health importance in tropical and subtropical countries. Although severe joint pain is the most distinguishing feature of chikungunya fever, diagnosis remains difficult because the symptoms of chikungunya fever are shared by many pathogens, including dengue fever. The present study aimed to develop a new immunochromatographic diagnosis test for the detection of chikungunya virus antigen in serum. Mice were immunized with isolates from patients with Thai chikungunya fever, East/Central/South African genotype, to produce mouse monoclonal antibodies against chikungunya virus. Using these monoclonal antibodies, a new diagnostic test was developed and evaluated for the detection of chikungunya virus. The newly developed diagnostic test reacted with not only the East/Central/South African genotype but also with the Asian and West African genotypes of chikungunya virus. Testing of sera from patients suspected to have chikungunya fever in Thailand (n = 50), Laos (n = 54), Indonesia (n = 2), and Senegal (n = 6) revealed sensitivity, specificity, and real-time PCR (RT-PCR) agreement values of 89.4%, 94.4%, and 91.1%, respectively. In our study using serial samples, a new diagnostic test showed high agreement with the RT-PCR within the first 5 days after onset. A rapid diagnostic test was developed using mouse monoclonal antibodies that react with chikungunya virus envelope proteins. The diagnostic accuracy of our test is clinically acceptable for chikungunya fever in the acute phase.

Continuous dengue type 1 virus genotype shifts followed by co-circulation, clade shifts and subsequent disappearance in Surabaya, Indonesia, 2008-2013.

Four serotypes of dengue virus (DENV-1 to DENV-4) and their genotypes are distributed in tropical and subtropical regions. Indonesia has been recently suggested as the origin of some dengue virus genotypes. In Surabaya, the second biggest city of Indonesia, we previously reported a shift of the predominantly circulating serotype from DENV-2 to DENV-1 in November 2008, followed by a genotype shift of DENV-1 from genotype IV (GIV) to genotype I (GI) in September 2009, based on nucleotide sequences in the envelope protein coding region. Since then, GI strains had predominantly circulated until December 2010. In this report, we investigated further DENV-1 transitions in Surabaya during 2011-2013 in order to comprehend dengue dynamics during 2008-2013 in more detail. From January 2011 through December 2011, only GIV strains were isolated, indicating that a genotype shift again took place from GI to GIV. In January 2012, GI and GIV strains started co-circulating, which continued until June 2013. To further investigate this phenomenon, analysis was performed at a clade level. GI and GIV strains isolated in Surabaya formed four and three distinct clades, respectively. Concomitant with co-circulation, new clade strains appeared in both genotypes. In contrast, some previously circulating clades were not isolated during co-circulation, indicating clade shifts. Among our Surabaya isolates, nucleotide and amino acid differences in the E region were, respectively, 1.0-2.3% and 0.2-1.0% for GI isolates and 2.0-6.3% and 0.0-1.8% for GIV isolates. Several characteristic amino acid substitutions in the envelope ectodomain were observed in some clades. After July 2013, DENV-1 strains were not isolated and were replaced with DENV-2. This study showed that continuous shifts of more than one genotype resulted in their co-circulation and subsequent disappearance and suggested the relevance of clade replacement to genotype co-circulation and disappearance in Surabaya.

Dengue virus type 1 strain isolated in Indonesia shows a close phylogenetic relationship with the strains that caused the autochthonous dengue outbreak in Japan in 2014

1Indonesia-Japan Collaborative Research Center for Emerging and Re-emerging Infectious Diseases, Institute of Tropical Disease, Airlangga University, Surabaya; 2Insani Clinic, Bogor; 3The Assessment Institute of Food, Drug and Cosmetics, Indonesian Council of Ulama LPPOM MUI, Bogor, Indonesa; 4Center for Infectious Diseases, Kobe University Graduate School of Medicine, Hyogo; and 5Department of International Health, Kobe University Graduate School of Health Sciences, Hyogo, Japan

Phylogenetic Analysis of Dengue Virus in Bangkalan, Madura Island, East Java Province, Indonesia

Dengue virus (DENV) infection is a major health issue in tropical and subtropical areas. Indonesia is one of the biggest dengue endemic countries in the world. In the present study, the phylogenetic analysis of DENV in Bangkalan, Madura Island, Indonesia, was performed in order to obtain a clearer understanding of its dynamics in this country. A total of 359 blood samples from dengue-suspected patients were collected between 2012 and 2014. Serotyping was conducted using a multiplex Reverse Transcriptase-Polymerase Chain Reaction and a phylogenetic analysis of E gene sequences was performed using the Bayesian Markov chain Monte Carlo (MCMC) method. 17 out of 359 blood samples (4.7%) were positive for the isolation of DENV. Serotyping and the phylogenetic analysis revealed the predominance of DENV-1 genotype I (9/17, 52.9%), followed by DENV-2 Cosmopolitan type (7/17, 41.2%) and DENV-3 genotype I (1/17, 5.9%). DENV-4 was not isolated. The Madura Island isolates showed high nucleotide similarity to other Indonesian isolates, indicating frequent virus circulation in Indonesia. The results of the present study highlight the importance of continuous viral surveillance in dengue endemic areas in order to obtain a clearer understanding of the dynamics of DENV in Indonesia.

Dengue virus infection-enhancing antibody activities against Indonesian strains in inhabitants of central Thailand

Dengue virus (DENV) infection-enhancing antibodies are a hypothetic factor to increase the dengue disease severity. In this study, we investigated the enhancing antibodies against Indonesian strains of DENV-1-4 in 50 healthy inhabitants of central Thailand (Bangkok and Uthai Thani). Indonesia and Thailand have seen the highest dengue incidence in Southeast Asia. The infection history of each subject was estimated by comparing his/her neutralizing antibody titers against prototype DENV-1-4 strains. To resolve the difficulty in obtaining foreign live viruses for use as assay antigens, we used a recombinant system to prepare single-round infectious dengue viral particles based on viral sequence information. Irrespective of the previously infecting serotype(s), most serum samples showed significantly higher enhancement titers against Indonesian DENV-2 strains than against Thai DENV-2 strains, whereas the opposite effect was observed for the DENV-3 strains. Equivalent enhancing activities were observed against both DENV-1 and DENV-4. These results suggest that the genotype has an impact on enhancing antibody activities against DENV-2 and DENV-3, because the predominant circulating genotypes of each serotype differ between Indonesia and Thailand.

Correction for Okabayashi et al., Detection of Chikungunya Virus Antigen by a Novel Rapid Immunochromatographic Test

Volume 53, no. 2, p. [382–388][1], 2015. Page 384, Fig. 1: Incorrect images were mistakenly placed in the second (Thai), fourth (S27), and sixth (SV) columns in the row labeled “Alphavirus Antibody.” The figure should appear as shown below. ![Figure][2] Page 385, Table 2: Several

Immunofluorescence assay method to detect dengue virus in Paniai-Papua

The dengue viruses (DENV), which include in the family Flaviviridae and the genus Flavivirus, was endemic in tropical areas and had been transmitted to humans by Aedes aegypti. An increasing number of immigrants from endemic areas to the non-endemic areas have emphasized the need for a simple and reliable test for the diagnosis of dengue virus infection. The purpose of this study was to detect the dengue virus by immunofluorescence assay (IFA) in the general population at Paniai-Papua. The results obtained from this study had showed a significantly better discrimination for DENV specific IgG antibodies. A total of 158 samples, 116 samples were IgG antibodies positive and 42 samples were negative. The conclusion of this study, Papua is not only a malaria endemic area, but also dengue virus infections were detected by IFA method. Therefore, the IFA can be used as an important diagnostic tool, which is a quick and an easy way to test samples from immigrants who come to the non-endemic areas.