Detection of the Marek Virus in Cockfight Roosters by the Polymerase Chain Reaction (PCR) Technique

Marek Disease (MD) is a lymphoproliferative disorder with polyneuritis in birds of the Gallus domesticus sp. The direct presence of the virus has remained unknown in Mexico. In order to determine its presence, a Polymerase Chain Reaction (PCR) was established, from the ICP4 conserved gene of the Gallid Herpesvirus-2, CVI988 attenuated strain (serotype 1) and the turkey Gallid Herpesvirus-2, FC126 strain (serotype 3). The PCR assay was done on the brain, nerve, lung, spleen, liver and feather calamus tissues from 24 cockfight roosters that showed signs suggestive to MD, such as: paralysis, ataxia, torticollis, fallen wings, neck and wings laxity. Tissues were also collected from 19 roosters without clinical neurological signs. Results showed that 6/25 roosters (25%) with clinical signs were positive by PCR to the ICP4 gene, from which 6/19 (31%) were positive by histopathology to MD and 4/24 (16%) were negative to the ICP4 gene, but positive by histopathology. A group of 5/24 roosters (21%), with signs suggestive to MD, were negative by PCR and histopathology to MD. One hundred percent of the roosters positive by PCR corresponded to the serotype 1, while one rooster was positive to serotype 3. Regarding roosters without MD signs, only 1/19 (5.2%) was positive by PCR corresponding to serotype 3. This study points out the presence of the Marek virus genome in cockfight roosters for the first time, detecting the highest frequency for the serotype 1.