Polymerase chain reaction for the differentiation of Marek's disease virus strains

The aim of this study was an attempt to apply PCR for diagnosis of Marek's disease. Eighteen field Marek's disease virus strains and 4 standard strains: virulent HPRS16 strain and attenuated CVI 988 strain (serotype 1 - MDV-1), apathogenic SE 1 strain (serotype 2 - MDV-2) and non - pathogenic turkeys HVT FC 126 strain (serotype 3 MDV-3) were used. Chicken anaemia virus (CAV) and infectious laryngotracheitis virus (ILTV) were used as control of PCR. The virus strains were cultured in CEF and total DNA was isolated by A@A Biotechnology kit. Three pairs of primers were used: for gene A of serotype 1, for 132 bp sequence of serotype 1 and for gene A of serotype 3. PCR was carried out under the following conditions: 94 degreesC - 1 min (denaturation). 55 degreesC - 30 s (annealing), 72 degreesC - 30 s (elongation). PCR products were analysed by electrophoresis in 2% agarose gel at 100 V/h. The PCR product of 314 bp was obtained from all field strains and HPRS16 standard after the primers for gene A of serotype 1 were used, After the primers for 132 bp sequence of serotype 1 were used, 434 bp fragment for 19 DNA samples derivied from field strains and standard HPRS16 strain and 1033 bp fragment from attenuated CVI 988 strain were obtained. Application of primers for gene A serotype 3 allowed the detection of 436 bp product only from non-pathogenic HVT FC 126 strain (serotype 3). These results indicated that the PCR technique can be used for the differentiation of MDV strains.