Characterization and thermostabilization of avibacterium paragallinarum candidate strains with potential use as candidate vaccine strains in Tanzania

This study was conducted to isolate, characterize, thermostabilize and develop an easier and cheap technique for preparation of inactivated and live vaccines against Infectious coryza (IC). Fifty six (56) samples were collected from chicken. Fourty eight percent (27) isolates had phenotypic characteristics suggestive of both pathogenic and non-pathogenic Avibacterium species. Fifty nine percent (16) of 27 isolates were catalase negative, oxidase positive and NAD dependent. Moreover, they were positive to fructose, maltose, and sucrose, but negative to lactose and urease suggesting that they were Avibacterium paragallinarum. Identification and serotyping by polymerase chain reaction (PCR) confirmed that they were Av. paragallinarum serovar B. Chocolate broth (CB), a novel medium was used to propagate Av. paragallinarum. The broth’s ability to support growth of Av. paragallinarum was compared to other three routine media and analysed using t- test. Results showed that null hypothesis was accepted between allantoic fluid (AF) and CB and between CB and modified brain heart infusion (MBHI) and was rejected between CB and brain heart infusion (BHI). The cost of production of 1 mL of CB was twenty six (26) times lower than the cost of producing AF and four (4) times lower than MBHI and BHI, therefore, CB is preferred as it is an easy to prepare and cheap medium. Av. paragallinarum isolates were thermostable at room temperature (RT) at the temperature range of 27-290C. The bacteria were recovered after storage for three months at RT in 2.5% gelatin. The findings from the present study have shown that Av. paragallinarum serotype B and other members of the genus Avibacterium exist in Tanzania. Propagation of Av. paragallinarum CB will possibly result in production of vaccines that are cheap and affordable to farmers. Furthermore, preservation of Av. paragallinarum in 2.5% gelatin for 3 months is a significant finding for development of live vaccines against IC