Atrophic rhinitis (AR) is the one of important respiratory diseases and causes severe economic losses in pig industry. Severe attempts have been made to reduce the economic losses by preventing the disease. One of the methods is the spraying of antibiotics into nasal cavity of piglets. Recently, the efficacy of the spraying with kanamycin and gentamicin was reduced in the Korean swine industry. Therefore, the preventive methods have been required to be changed based on the antimicrobial susceptibility profiles of causative agents of swine AR. Based on the current situations of this disease, Bordetella (B.) bronchiseptica and Pasteurella (P.) multocida 4D were isolated from pigs with clinical signs of AR. The isolation rates of B. bronchiseptica and P. multocida 4D were 58.5% and 32.9%, respectively. In the antimicrobial susceptibility test, the bacteria were resistant to kanamycin and gentamicin which have been used as the spraying agents, but they were susceptible to amikacin. A new spraying agent was developed using amikacin using β-glucan and yakbaltag as supplementary agents. Field efficacy of the agent was carried out with different schedule. The results from this study suggested that the newly developed spraying agents might be helpful to prevent AR in swine.

We have investigated efficiency of a recombinant subunit Pasteurella multocida toxin (PMT) that was mixed with a vaccine consisted of inactivated whole cells of Bordetella bronchiseptica, P. multocida (type A and D). For verification of the efficacy of the vaccine, all experimental pigs (suckling piglets, sow and gilts) in the three farms were vaccinated. Antibody titers against B. bronchiseptica and P. multocida type A of the vaccinated pigs by microplate agglutination were significantly higher than those of the control pigs (p less than 0.05). Similar patterns were observed in the analysis of anti- PMT neutralizing antibody by serum neutralizing method using Vero cell (p less than 0.05). Anti- P. multocida type D antibody titer of the vaccinated sows and gilts by ELISA showed significant differences with those of the non-vaccinated pigs (p less than 0.05). Although antibody titers increased, it was unable to fine out the differences in the clinical signs between the vaccinated and non-vaccinated pigs. However, the increase in body weight of the vaccinated piglets was observed in comparison with the non-vaccinated piglets on a farm. At slaughtering of the pigs, pathological lesions in the turbinate bones of the vaccinated pigs were significantly lower than those of the non-vaccinated pigs (p less than 0.001). These results suggested that efficacy of the vaccine in pigs demonstrated to protect against atrophic rhinitis in Korea.

Pasteurella multocida D:4 producing Pasteurella multocida toxin (PMT) is a causal pathogen in atrophic rhinitis in pigs. To investigate the protective immunity and vaccination effect of recombinant PMT, the gene for PMT was isolated from the infective P. multocida D:4. The 2.3 kb XhoI/PstI fragment (PMT2.3) of PMT gene was expressed in E. coli BL21 (DE3) using the induced expression vector system. The recombinant protein of PMT2.3 having molecular weight of 84 kDa was purified by Ni-affinity column chromatography.

This paper describes the slaughter check results of breeding pigs from the Korean Swine Testing Station for the control of endemic diseases. Gross lesions monitored in the present study included those conditions commonly associated with economically significant subclinical herd infections enzootic pneumonia, pleuropnemonia, pleuritis, atrophic rhinitis, liver white spots, papular dermatitis and ileitis. A total of 128 slaughter pigs were investigated at 4 subsequent tests according to the slaughter check procedures established.