R. Govindarajan

Detection of Leptospira and Brucella genomes in bovine semen using polymerase chain reaction

Animal breeders have used artificial insemination (AI) extensively since the 1930s and 1940s, mainly in cattle and to some extent in pigs and sheep. By using the techniques available, semen can be collected from male animals at an artificial insemination centre and stored for varying periods at low temperatures. The semen can then be distributed to the surrounding area and throughout the country, and can also be exported to other countries. Thus, as well as providing desired genetic characteristics, the semen could act as a vehicle for the wide distribution of undesirable pathogens. Increasing international trade in germplasm emphasizes the need for rapid, sensitive and specific diagnostic tests for certification of semen free from an increasing list of pathogenic agents (Afshar and Eaglesome, 1990; Eaglesome and Garcia, 1992; Eaglesome et al., 1992). Bacterial isolation and co culture methods are presently used to detect pathogens in the semen. However, low levels of microbes, and the presence of antibiotics and inhibitors in the semen, diluted as in the artificial insemination centres with extenders, limit the sensitivity of these assays. The polymerase chain reaction (PCR) is advantageous over other techniques because of its ability to amplify within a few hours, a specific sequence of pathogen present at low concentration in semen. Since PCR detects nucleic acid of microbes irrespective of their capacity to cause infection, this technique has the advantage to screen potential pathogens or persistent viral and bacterial infections. Detection of infectious agents in the semen with a sensitive assay like PCR would eliminate the use of infected animals as semen donors, thereby ensuring the reproductive health of inseminated cows. Endometritis, early embryonic death, repeat breeding and the consequence of which protracts the inter calving period, retained placenta, and above all the most obvious manifestation namely abortion can be thwarted. Similarly, a latently infected pedigreed bull need not be condemned for the fear of shedding the infectious agents, as a very sensitive method is now available for screening. Hence, this research was undertaken with the objective of optimizing a PCR assay in relation to the method of DNA extraction to Trop Anim Health Prod (2008) 40:323–329 DOI 10.1007/s11250-007-9110-5