| Summary: | 碩士 === 國立中興大學 === 獸醫微生物學研究所 === 87 === Abstract
Infectious coryza (IC), caused by Haemophilus paragallinarum (HP), is an acute upper respiratory disease in chicken. Although the inactivated vaccines were commonly used, many cases of vaccine failure were still found in Taiwan. The purposes of this study are to conduct the investigation of epidemiology and HP isolates, and comparison of protection of various HP vaccines with aluminum hydroxide gel adjuvant. From 1995 to 1997, fourteen strains of HP were isolated from IC infected chickens submitted from the central area of Taiwan. All of the fourteen isolates belonged to serotype C identified by using 5 monoclonal antibodies. The drug sensitivity was also carried for the isolates of this study. Among the sensitive drugs, Ampicillin and Cefazoline were found most sensitive to HP isolates. The next sensitive drugs were Tetracycline, Sulfamethoxazole-Trimethoprim, and Chloramphenical. One of the isolates, TS-1 isolate, was used for the preparation of HP inactivated vaccine with aluminum hydroxide gel in the concentration of 1X109 colony forming unites (CFU) per milliliter. In the protectively experiment, specific pathogen-free (SPF) chicks were grouped and vaccinated by two doses of 0.25 ml and 0.5 ml at 5 week-old, followed by another two doses of 0.5 ml and 1.0 ml at 15 week-old in the route of intra-muscle. The vaccinated experimental chickens were challenged at 20 week-old with TS-1 strain by eye-nostril route. Examination of clinical signs, haemagglutination inhibition (HI) titers, and bacterial recovery was carried at ninth day of post-challenge. The results showed that the protective rates were 87.5% and 100% in vaccinated chicken groups of 0.25 ml + 0.5 ml and 0.5 + 1 ml, respectively, and were effective until 25 weeks of age. Antibodies of aluminum hydroxide gel vaccines of TS-1 strains were also measured and compared with those of market available vaccines. In the results of serotype C antibody, they showed that antibody titers measured by the HI test at 8 week-old were 3.91 in both groups of B (that was imported bivalent vaccines for infectious coryza) and E-1 (that was produced with TS-1 wild strain isolated in Taiwan by our laboratory), which were significantly highest among the vaccinated groups. After boosting of each vaccine, the group of C-2 (that was imported mixed vaccine for both ND and IC) revealed the highest HI titer of 6.32 at the age of 18 weeks. However, among the tested vaccines, the serotype C HI titers of D (that was mixed vaccine for ND and IC produced by the manufacture in Taiwan) could not be measured. In the results of serotype A antibody, they showed that antibody titers measured by the HI test at 8 week-old were 4.38 in the groups of B, which were significantly highest among the vaccinated groups. After boosting of each vaccine, the group of C-2 revealed the highest HI titer of 4.27 at the age of 18 weeks. By the results of HI titration of Newcastle disease virus (NDV), the immune response of NDV was independent against that of HP by inoculating the bivalent vaccines of NDV and HP in the experimental
chickens.
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