Pathogenesis ofGallibacterium anatisin a natural infection model fulfils Koch’s postulates: 2. Epididymitis and decreased semen quality are the predominant effects in specific pathogen free cockerels

Abstract

Pathogenesis of Gallibacterium anatis was investigated in specific pathogen free cockerels. Birds aged 35 weeks were infected intranasally with G. anatis whereas negative controls were left uninfected. Following infection, necropsy, bacteriological and histopathological investigations were performed in birds killed at 3, 7, 10, 28 and 38 days post infection (d.p.i.). Additionally, semen samples were collected twice a week until 5 weeks post infection for quality assessment. No clinical signs and gross pathological lesions were seen throughout the experiment. Bacteriological investigation revealed that G. anatis colonized the upper respiratory tract at 3 d.p.i. and could be isolated from testis and epididymis at 7 d.p.i. onwards. Bacterial persistence was found in the respiratory tract, gut and testis until the termination of the study at 38 d.p.i. Furthermore, G. anatis was isolated from semen arguing for the possibility of vertical transmission. Histopathological examination showed infiltration of mononuclear cells in epididymal tissue, indicating an inflammation. Density, total motility, progressive motility and membrane integrity of sperms were significantly decreased in infected birds as compared with control chickens. Along with these findings, an increase in spermatozoa with morphological defects was observed at different time points. In conclusion, the present study provides novel data on the impact of a G. anatis infection in cockerels in a natural infection model, thus helping to elucidate bacterial distribution, pathological lesions as well as influences on semen quality.

Etiology, epidemiology, pathology, and advances in diagnosis, vaccine development, and treatment ofGallibacterium anatisinfection in poultry: a review

“…anatis has been noted in four-day-old poultry birds by quantitative PCR (qPCR) (Huangfu et al 2012) and also been isolated from the egg yolks and ovarian follicles of adult hens ten days after intranasal inoculation, supporting the vertical transmission hypothesis (Kohlert 1968;Janetschke & Risk 1970;Shapiro et al 2013;. G. anatis causes epididymitis and affects semen quality, consistent with the presumed venereal transmission (Paudel, Liebhart, Aurich, et al 2014). In natural cases, reproductive tract organs are affected mostly through ascending infections Neubauer et al 2009).…”

“…Gallibacterium have been reported across the world, such as European countries including Switzerland, Denmark, Germany, Norway, England, Sweden, Czech Republic and Austria (Mr az et al 1976;Bisgaard 1977;Mirle et al 1991;Neubauer et al 2009;Jones et al 2013); African countries like Nigeria, Egypt, Morocco (Addo & Mohan 1985;Elbestawy et al 2018;Nassik et al 2019); Asian countries including China, Taiwan, Iran, Syria, India and Japan (Suzuki et al 1996;Guo 2011;Huangfu et al 2012;Ataei et al 2017;Zhang et al 2017;Singh et al 2018); American countries such as the USA, Canada, Colombia, Peru and Mexico (Hacking & Pettit 1974;Shaw et al 1990;Bojesen et al 2008;Mendoza et al 2014;Paudel, Liebhart, Aurich, et al 2014;Ch avez et al 2017); and Australia (Jordan et al 2005). G. anatis, particularly biovar hemolytica, has recently gained importance due to its ability to cause both respiratory and reproductive infections, and its occurrence in countries on various continents including Europe, Asia, America, and Africa (Neubauer et al 2009).…”

“…are involved in causing septicemia (Fisher et al 1998;Ewers et al 2004;Abdul-Aziz et al 2016). In recent past, several reports of clinical cases in avian and experimental studies in chickens revealed Gallibacterium anatis to be an important bacterial pathogen associated with septicemia (Bojesen et al 2004;Neubauer et al 2009;Jones et al 2013;Paudel et al 2013;Elbestawy 2014;Paudel, Liebhart, Aurich, et al 2014;Paudel et al 2015;Persson & Bojesen 2015).…”

“…G. anatis has been considered as a primary organism associated with lowered egg production, leading to 8-10% yield reduction and found to cause mortality up to 73% in experimentally immunosuppressed layer chickens (Mirle et al 1991;Jordan et al 2005;Neubauer et al 2009;Shapiro et al 2013). In cockerels, this bacterium causes epididymitis and leads to decreased semen quality (Paudel, Liebhart, Aurich, et al 2014). In young chickens the lesions are systemic in nature (Zepeda et al 2010;Paudel et al 2013;Zhang et al 2019).…”

Commensal or pathogen – a challenge to fulfil Koch’s Postulates

“…This research indicated that the intranasal route of infection was very suitable to mimic the clinical situation. Based on this study, two further separate experimental trials in mature SPF chickens, hens and cockerels, were performed (Paudel et al ., 2014 a , 2014 b ). Macroscopic and microscopic lesions in the reproductive tract were successfully induced and the infection resulted in a drop in egg production due to severe folliculitis in addition to egg peritonitis.…”