Distribution of Japanese Encephalitis Virus, Japan and Southeast Asia, 2016-2018.

During 2016-2018, we conducted surveillance for Japanese encephalitis virus (JEV) in mosquitoes and pigs in Japan, Thailand, the Philippines, and Indonesia. Phylogenetic analyses demonstrated that our isolates (genotypes Ia, Ib, III, IV) were related to JEV isolates obtained from the same regions many years ago. Indigenous JEV strains persist in Asia.

Getah virus epizootic among wild boars in Japan around 2012.

In 2014, an outbreak of Getah virus (GETV) infection occurred in Japan in a horse population that was inoculated with a vaccine against GETV. In this study, we investigated the seroprevalence of GETV infection among wild boars in Japan. Interestingly, the highest rate of anti-GETV-positive wild boars was observed in 2013, which gradually decreased during 2014-2016. The results suggested that GETV spread among wild boars around 2012, resulting in the 2014 outbreak.

Effects of Colonization of the Roots of Domestic Rice (Oryza sativa L. cv. Amaroo) by Burkholderia pseudomallei.

Burkholderia pseudomallei is a saprophytic bacterium that causes melioidosis and is often isolated from rice fields in Southeast Asia, where the infection incidence is high among rice field workers. The aim of this study was to investigate the relationship between this bacterium and rice through growth experiments where the effect of colonization of domestic rice (Oryza sativa L. cv Amaroo) roots by B. pseudomallei could be observed. When B. pseudomallei was exposed to surface-sterilized seeds, the growth of both the root and the aerosphere was retarded compared to that in controls. The organism was found to localize in the root hairs and endodermis of the plant. A biofilm formed around the root and root structures that were colonized. Growth experiments with a wild rice species (Oryza meridionalis) produced similar retardation of growth, while another domestic cultivar (O. sativa L. cv Koshihikari) did not show retarded growth. Here we report B. pseudomallei infection and inhibition of O. sativa L. cv Amaroo, which might provide insights into plant interactions with this important human pathogen.

High Seroprevalence of Severe Fever with Thrombocytopenia Syndrome Virus Infection among the Dog Population in Thailand.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne zoonotic disease caused by the SFTS virus (SFTSV). In Thailand, three human cases of SFTS were reported in 2019 and 2020, but there was no report of SFTSV infection in animals. Our study revealed that at least 16.6% of dogs in Thailand were seropositive for SFTSV infection, and the SFTSV-positive dogs were found in several districts in Thailand. Additionally, more than 70% of the serum samples collected at one shelter possessed virus-neutralization antibodies against SFTSV and the near-complete genome sequences of the SFTSV were determined from one dog in the shelter. The dog SFTSV was genetically close to those from Thailand and Chinese patients and belonged to genotype J3. These results indicated that SFTSV has already spread among animals in Thailand.

Porcine pancreas: a superior source of cholesterol esterase for total serum cholesterol assay by the enzymatic kinetic method.

BACKGROUND: Accurate determination of cholesterol requires complete hydrolysis of cholesteryl esters and must be very fast for the kinetic cholesterol assay. We investigated the properties of cholesterol esterase derived from Pseudomonas fluorescens, Candida cylindracea, bovine pancreas, and porcine pancreas for cholesterol determination in human serum. METHODS: Optimization of four enzymes and effect of sodium cholate concentration were performed. We evaluated and compared their performances in enzymatic kinetic cholesterol determination. RESULTS: The optimal sodium cholate concentration was 3, 5, 15, and 12 mmol/l with the enzyme activities at 200, 100, 100, and 100 U/l for P. fluorescens, C. cylindracea, bovine pancreas, and porcine pancreas, respectively. Linearity obtained from all enzymes was up to 16.3 mmol/l. All assays were compared favorably with standardized endpoint method. Only the cholesterol esterase derived from porcine pancreas demonstrated acceptable precision within the acceptable criteria (%CV < 3.0). Also, this esterase was least affected by interfering substances and showed longer stability than that of C. cylindracea and bovine pancreas. CONCLUSION: Porcine pancreas cholesterol esterase is superior to that obtained from P. fluorescens, C. cylindracea, and bovine pancreas for total serum cholesterol determination by the kinetic method because of its lower cost, better accuracy and precision, less interference, and longer stability.

A serological survey and characterization of Getah virus in domestic pigs in Thailand, 2017-2018.

Getah virus (GETV) is a mosquito-borne RNA virus belonging to the family Togaviridae, genus Alphavirus. GETV infection causes diarrhoea and death in piglets, and reproductive failure and abortion in sows. This study conducted a serological survey of GETV infection among domestic pig populations in Thailand. ELISA was used to analyse 1,188 pig serum samples collected from 11 provinces of Thailand during 2017-2018, with 23.1% of the samples being positive for anti-GETV antibodies. The positive ratio of anti-GETV antibodies was significantly higher in nursery (67.9%) and older stages (84.5%) of pigs than in finishing stage (14.2%). Furthermore, we successfully isolated GETV from one pig serum, designated as GETV strain GETV/SW/Thailand/2017, and determined the complete genome sequence (11,689 nt). Phylogenetic analysis demonstrated that our isolate was different from the recent GETV group spreading among pig populations in East Asia and formed a cluster with two GETV strains, namely YN12031 (China, 2015) and LEIV16275Mar (Far-East Russia, 2007). We concluded that two different GETV groups are currently spreading among pig populations in Asian countries.