Rabbit listeriosis is one of the major diseases problems that facing rabbit breeding and industry in Egypt. Listeria monocytogenes is the main responsible food borne pathogen for listeriosis in humans, rabbits and many animal species. The scope of the present study was to discuss the phenotypic and genotypic characterization of some virulence genes (16s rRNA, hlyA and iap) of L. monocytogenes isolates in rabbits and to show the correlation between the intensity of the experimental infection and hematological, biochemical changes and their effects on the immune status of the animal. Conventional bacteriological examination for isolation of L. monocytogenes was applied for all collected samples including culturing on specific media and biochemical identification test. Samples were collected from suspected cases of rabbit farms in Ismailia Governorate. Moreover, an oral experimental trial for induction of listeriosis in two groups of rabbits (1st was the infected group and 2nd was the control) was also, done. L. monocytogenes was isolated from rabbit farms in a percentage of 21.8% (12/55) however; experimentally it was reisolated from all rabbits of the 1st group. Microcytic hypochromic anaemia, leukocytosis associated with neutrophilla, lymphopenia and monocytosis were observed in experimentally infected rabbits at 7 days p.i. and leukocytosis with neutrophilia and monocytosis in 15 days p.i. A highly significant elevation in the activities of ALT and AST, hypocalcemia associated with significant increase in uric acid, creatinine and inorganic phosphorus were observed in infected group. Meanwhile, highly significant decrease in total proteins associated with decrease of total globulins especially alpha and beta-globulin and hypoalbuminemia but increased gamma globulin in 15 days p.i. were recorded. PCR analysis of 16S rRNA gene was applied for the molecular identification and differentiation of L. monocytogenes from other Listeria species. 16S rRNA gene was found in all the recovered isolates (100%).
Also, the genotypic detection of some virulent genes with PCR revealed that hly A gene was detected in (11/12) of L. monocytogenes isolates (91.7%) meanwhile, iap gene gave clear bands at 193 bp in all isolates (100%) confirming more virulence and pathogencity of these isolates. Recommendation of successful preventive, good sanitation programs and control measures in rabbit farms should be implemented.
Also, further in vitro and in vivo studies for the role and mechanism of other virulence factors of L. monocytogenes in rabbit in Egypt should be discussed and explained to prevent the spreading of listeriosis disease in rabbit and for the improvement of the rabbit industry in Egypt.