Various viral and bacterial pathogens interact with environmental factors to cause diarrhea in piglets. Enterococcus spp. are Gram-positive anaerobic bacteria that are commonly found in the gastrointestinal tract of several animal species, including pigs. Enterococcus spp. have been reported to infect several animal species as a pathogen. However, gastrointestinal infection by Enterococcus hirae is rare in pigs; only a few cases have been reported worldwide. Four piglets with diarrhea were examined in the diagnostic laboratory of Optipharm Inc. (Cheongju, Korea). During the initial post-mortem examination, no disease lesions were observed. Upon microscopic examination, we found numerous Gram-positive cocci that were adhered to epithelial villi in the jejunum and ileum. However, the villi did not exhibit significant structural damage. Cultured bacteria were identified as E. hirae using the VITEK 2 system and polymerase chain reaction (PCR). Using PCR, we also confirmed that viruses and protozoa that can potentially infect piglet intestines were absent. In antibiotic susceptibility test, the bacteria were resistant to most types of antibiotics. This study presents rare cases of E. hirae infection of the piglet small intestine, which can occur in association with diarrhea possibly by the continuous use of antibiotics.

Antigen production in plant is a safe and effective strategy for vaccine development. In this study, rice transformants were developed for oral vaccine against pigs diarrhea disease. DNA cassette composed with the cholera toxin subunit B (CTB) connected to the 987P-fasG, for stimulating a strong oral immune response, was introduced to rice through Agrobacterium mediated genetic transformation. Copy number analysis by TaqMan real-time PCR for transgenes revealed that transgene of 1 to 8 copies have been introduced into T1 and T2 rice seeds. The expression level of mRNA in the transformants T1 and T2 generations were up to 35 times higher than the reference value in the result of analysis by Quantitative real time-PCR. In addition, the callus cultured from rice transformants was confirmed that the introduced gene has been maintained till 9-month subculture duration. The amount of mRNA expression value was also confirmed in callus, which was maintained above 2.6 times compared with that of the standard control for a long time. These results provide that the introduced antigen for plant-based vaccine against bacterial diarrhea disease can be maintained in the callus as well as in the transgenic plant and suggest that the callus culture of plant transformant will be an effective way to obtain a plant-derived edible vaccine.