ORIGINAL ARTICLE The possible role of bovine herpesvirus type-4 infection in cow infertility Sibel GÜR 1 and Nurhan DOG ˘ AN 2 1 Department of Virology, Faculty of Veterinary Medicine, and 2 Department of Biostatistics, Faculty of Medicine, Afyon Kocatepe University, Afyonkarahisar, Turkey ABSTRACT Experimental and field studies have proven that the bovine herpesvirus type-4 (BHV-4) infection leads to various reproductive system problems. In this study, the role of BHV-4 infection in repeat breeding was investigated serologically. Eighty-four samples were obtained from repeat-breeding diagnosed cows in two organized dairy herds; an equal number of healthy cows were sampled from the same farms. The rest of the samples (105) were obtained from reproductively normal cows that were breeding in 18 small enterprises as a control group. The seropositivity proportion in repeat-breeding diagnosed cows was found to be significantly higher (69% (58/84)) than other cows (44% (37/84)) on the same farms. The lowest antibody positivity value for BHV-4 was detected as 24.7% (26/105) in the samples from family-type small farms. The odds ratio (OR) value was calculated as 2.834 in repeat-breeding diagnosed and healthy cows on the same farms, while 6.778 was determined in cows with and without reproductive problems on organized farms compared to small farms. As a result, the BHV-4 infection can be considered one of the reasons for repeat breeding besides other reproductive disorders. Key words: bovine herpesvirus type 4, cattle, infertility, repeat breeding. INTRODUCTION Bovine herpesvirus type-4 (BHV-4) was classified in a Gamaherpesvirus subfamily (Bublot et al. 1990, 1992; Roizman et al. 1992). The agent was isolated (Bartha et al. 1966) for the first time in 1963 from sick animals with respiratory and ocular symptoms in Europe. The agent was divided into two groups by means of restric- tion endonuclease analysis (Bublot et al. 1992; Thiry et al. 1992); Movar 33/63-like viruses were isolated from Europe, and DN 599-like viruses were isolated from North America (Bartha et al. 1966; Mohanty et al. 1971; Storz et al. 1984; Henry et al. 1986; Dubuisson et al. 1988; Thiry et al. 1992). The natural host of the virus is primarily cattle, but several ruminant (Dewals et al. 2006) and non-ruminant species are susceptible to BHV-4 (Egyed et al. 1997). The BHV-4 virus was isolated from both clinically healthy (Luther et al. 1971) and ill cattle that have respiratory disorders (Bartha et al. 1966), metritis (Wellemans et al. 1984; Frazier et al. 2001), abortion (Czaplicki & Thiry 1998), mastitis (Wellenberg et al. 2000; Kalman et al. 2004; Izumi et al. 2006), encepha- litis, diarrhea, vulvovaginitis and skin lesions in both natural and experimental infection (Osorio & Reed 1983; Thiry et al. 1990; Goyal & Naeem 1992; Miyano et al. 2004). The latent character of the BHV-4-like other herp- esviruses can be a hindrance for clinical diagnosis, but virus reactivation is possible with dexametasone treat- ment (Osorio & Reed 1983; Castrucci et al. 1987) and stress factors. BHV-4 infection leads to production of a low anti- body avidity (Thiry et al. 1990), by way of sensitive tests required for antibody detection, such as enzyme- linked immunosorbent assay (ELISA) (Edwards & Newman 1985), in cases of complement fixation (Guo et al. 1988), and the indirect fluorescent antibody test (IFAT) (Sass et al. 1974). After an experimental infection, the virus accumu- lates in the internal organs, such as the trachea, the spleen, the lung, the kidney, the liver, the tonsils, and the intestines (Egyed et al. 1996). Herpesviruses affect Correspondence: Sibel Gür, Afyon Kocatepe University, Faculty of Veterinary Medicine, Department of Virology, ANS Campus, 03200, Afyonkarahisar, Turkey. (Email: sibelgur@aku.edu.tr) Received 28 May 2009; accepted for publication 15 Septem- ber 2009. Animal Science Journal (2010) 81, 304–308 doi: 10.1111/j.1740-0929.2010.00743.x © 2010 The Authors Journal compilation © 2010 Japanese Society of Animal Science