Detection and genetic analysis of zoonotic hepatitis E virus, rotavirus, and sapovirus in pigs

The zoonotic transmission of viral diseases to humans is a serious public health concern. Pigs are frequently a major reservoir for several zoonotic viral diseases. Therefore, periodic surveillance is needed to determine the infection rates of zoonotic diseases in domestic pigs. Hepatitis E virus (HEV), rotavirus, sapovirus (SaV), and norovirus (NoV) are potential zoonotic viruses. In this study, 296 fecal samples were collected from weaned piglets and growing pigs in 13 swine farms, and the viral RNA was extracted. Partial viral genomes were amplified by reverse transcription-polymerase chain reaction (PCR) or nested-PCR using virusspecific primer sets under different PCR conditions. HEV-3, rotavirus A, and SaV genogoup 3 were detected from 11.5, 2.7, and 3.0% of the samples, respectively. On the other hand, NoV was not detected in any of the samples. Genetic analysis indicated that the nucleotide sequences of swine HEV-3 and rotavirus A detected in this study were closely related to those of human isolates. However, swine SaV was distant from the human strains. These results suggest that HEV-3 and rotavirus A can be transmitted from pigs to humans. Therefore, strict preventive measures should be implemented by workers in the swine industry to prevent infections with HEV-3 and rotavirus A excreted from pigs.

Detection of hepatitis E virus genotypes 3 and 4 in pig farms in Korea

Zoonotic transmission of hepatitis E virus (HEV) is mostly mediated by HEV-3 and HEV-4 genotypes, and domestic pigs are an important reservoir of these genotypes. A survey of 14 pig farms in Korea revealed HEV RNA in 30 of 148 (20.3%) fecal samples. HEV-3a and HEV-4c subtypes were identified in five pig farms (35.7%) and two pig farms (14.3%), respectively. Phylogenetic analysis indicated that the isolated HEV strains were closely related to previously reported zoonotic strains in Korea. The results of the genetic analysis partially explain the possible source of the zoonotic transmission of HEV to humans in Korea.

Evaluation of immunocontraceptive vaccine composed of gonadotropin-releasing hormone conjugated with granulocyte-macrophage colony-stimulating factor in male rats

Surgical castration performed to reduce male-associated problems results in pain and microbial infections in male animals. Therefore, immunocontraception, which is mediated by the animal's own antibodies against reproductive hormones, has been recommended as an alternative to surgical castration when considering the animal's welfare. In this study, a new immunocontraceptive vaccine composed of six tandem copies of gonadotropin-releasing hormone (GnRH) fused to rat granulocyte-macrophage colony-stimulating factor (GM-CSF) was developed, and its efficacy was evaluated in male rats. Three different doses (10, 50, and 100 µg) of recombinant GM-CSF–GnRH protein were injected three times at intervals of two weeks into male rats. The rats vaccinated with three doses of GM-CSF–GnRH produced a significantly higher level of antibodies against GnRH than that in the negative control rats. Severe atrophy of gonads was observed in rats vaccinated with three doses of GM-CSF–GnRH but not in the negative control rats. The results reveal that the new GnRH vaccine conjugated with rat GM-CSF induces efficient immunocontraception in male rats. This formulation of the immunocontraceptive vaccine would be applicable to both domestic and pet male animals.