Seroprevalence of bovine arboviruses belonging to genus Orthobunyavirus in South Korea.

Arboviruses, belonging to the Simbu serogroup of the genus Orthobunyavirus, often cause congenital malformations and reproductive loss in cattle. The recent occurrences of such reproductive problems suggest that new arboviruses have emerged in Japan. However, there is no information on the presence of these viruses in South Korea. The aim of this study was to determine the presence of antibodies for Akabane, Aino, Peaton, Sathuperi, and Shamonda viruses in four regions, namely Gyeonggi, Jeollabuk, Jeollanam provinces, and Jeju Island of South Korea by a serum neutralization test. Antibody positivity against Akabane, Aino, Peaton, Sathuperi, and Shamonda viruses was detected in the country, with average seropositive rates of 10.4, 4.5, 1.1, 4.9, and 5.6%, respectively.

Simple method for Shiga toxin 2e purification by affinity chromatography via binding to the divinyl sulfone group.

Here we describe a simple affinity purification method for Shiga toxin 2e (Stx2e), a major causative factor of edema disease in swine. Escherichia coli strain MV1184 transformed with the expression plasmid pBSK-Stx2e produced Stx2e when cultivated in CAYE broth containing lincomycin. Stx2e bound to commercial D-galactose gel, containing α-D-galactose immobilized on agarose resin via a divinyl sulfone linker, and was eluted with phosphate-buffered saline containing 4.5 M MgCl2. A small amount of Stx2e bound to another commercial α-galactose-immobilized agarose resin, but not to ß-galactose-immobilized resin. In addition, Stx2e bound to thiophilic adsorbent resin containing ß-mercaptoethanol immobilized on agarose resin via a divinyl sulfone, and was purified in the same manner as from D-galactose gel, but the Stx2e sample contained some contamination. These results indicate that Stx2e bound to D-galactose gel mainly through the divinyl sulfone group on the resin and to a lesser extent through α-D-galactose. With these methods, the yields of Stx2e and attenuated mutant Stx2e (mStx2e) from 1 L of culture were approximately 36 mg and 27.7 mg, respectively, and the binding capacity of the D-galactose gel and thiophilic adsorbent resin for Stx2e was at least 20 mg per 1 ml of resin. In addition, using chimeric toxins with prototype Stx2 which did not bind to thiophilic adsorbent resin and some types of mutant Stx2e and Stx2 which contained inserted mutations in the B subunits, we found that, at the least, asparagine (amino acid 17 of the B subunits) was associated with Stx2e binding to the divinyl sulfone group. The mStx2e that was isolated exhibited vaccine effects in ICR mice, indicating that these methods are beneficial for large-scale preparation of Stx2e toxoid, which protects swine from edema disease.

A specific induction of interleukin-10 by the Map41 recombinant PPE antigen of Mycobacterium avium subsp. paratuberculosis.

Interleukin-10 (IL-10) is not only an essential immunoregulator in host immunity, but also it accounts for the intracellular survival of mycobacteria because of its inhibitory activity against anti-mycobacterial functions of macrophage. It has been also indicated that blood cells from calves infected with Mycobacterium avium subsp. paratuberculosis (Map) produce a large amount of IL-10 after stimulation with Map antigen, and it leads to suppression of Interferon-gamma (IFN-gamma) production in T-cells. This characteristic expression of IL-10 in Map-infected cattle seems to be playing important roles in the pathogenesis of Johne's disease caused by Map, and could be an important diagnostic indicator. The aim of this study was to investigate the diagnostic significance of IL-10 production from blood cells stimulated by a PPE (Proline-Proline-Glutamic acid) protein family of Map. The recombinant PPE protein, Map41, which has been reported as one of the IFN-gamma inducing antigens of Map, also strongly induced IL-10 from macrophages obtained from infected calves. The elicited IL-10 production in response to Map41 from experimentally infected calves was as early as 2 weeks after the inoculation of Map, and the IL-10 production was detected earlier than that of IFN-gamma. The blood cells from calves immunized with Map produced higher amounts of IL-10 against Map41 stimulation than those of calves immunized with various Mycobacterium species. Furthermore, this IL-10 induction also showed high specificity to Map in guinea pigs experimentally infected with various Mycobacterium species. These observations suggest that IL-10 assay is a useful diagnostic method in the early stage of Johne's disease.