Enhancement of avian influenza virus infectivity by proteolytic bacteria

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" Enhancement of avian influenza virus infectivity by proteolytic bacteria "
B. R. Byrum R. D. Slemons

Document Type	:	Latin Dissertation
Language of Document	:	English
Record Number	:	1112951
Doc. No	:	TLpq304100575
Main Entry	:	B. R. Byrum
	:	R. D. Slemons
Title & Author	:	Enhancement of avian influenza virus infectivity by proteolytic bacteria\ B. R. ByrumR. D. Slemons
College	:	The Ohio State University
Date	:	1994
student score	:	1994
Degree	:	Ph.D.
Page No	:	155
Abstract	:	The objective of this study was to evaluate the potential role of proteolytic bacteria in the exacerbation of avian influenza (AI) infections in poultry. Initially, numerous proteolytic bacteria were recovered from tracheal swabs of chickens and turkeys. Six proteolytic bacteria selected for further in vitro studies included Staphylococcus aureus, S. epidermis, S. hyicus, S. gallinarum, Flavobacterium sp. and Vibrio alginolyticus. Avian influenza viral isolates included in the in vitro studies were A/turkey/Wisconsin/68 (H5N9), A/turkey/Ohio/88 (H1N1), A/chicken/Alabama/75 (H4N8), A/mallard/Ohio/338/86 (H4N8) and A/mallard/Ohio/184/86 (H5N1). When purified protease secreted by Vibrio alginolyticus was added to cell culture medium there was a significant increase (Wilcoxon Rank Sum p = 0.02) in the mean tissue culture infective dose (TCID{50}) of both A/turkey/Wisconsin/68 and A/mallard/Ohio/184/86. However, this protease did not enhance the infectivity of the other three AI isolates and purified proteases from the other bacteria did not increase the infectivity of any of the five AI isolates. Subsequent in vivo experiments demonstrated significantly higher AI virus titers in lung tissues of seven-day-old specific-pathogen-free turkeys challenged with A/turkey/WI/68 and Vibrio alginolyticus compared to turkeys challenged with A/turkey/WI/68 alone (Wilcoxon Rank Sum p = 0.002). Also, histopathological analysis demonstrated significantly higher tracheal lesion scores in turkeys challenged with A/turkey/WI/68 and Vibrio alginolyticus compared to birds challenged with the bacteria or virus alone (Wilcoxon Rank Sum p = 0.01) on day 3 post inoculation. Data presented in this study provides preliminary evidence supporting the theory that co-infecting proteolytic bacteria can enhance the pathogenicity of low and nonpathogenic avian influenza isolates in turkeys.
Subject	:	Biological sciences
	:	influenza
	:	Microbiology
	:	Veterinary services