Complete nucleotide sequence analysis of the oncogene “Meq” from serotype 1 Marek’s disease virus isolates from India

ABSTRACT

1. A study was undertaken to characterise the oncogene Meq at the molecular level for three serotype 1 Marek’s disease virus (MDV) field isolates from vaccinated poultry flocks which had encountered a Marek’s disease outbreak in the southern part of India. The isolates were named Ind/TN/11/01, Ind/KA/12/02 and Ind/TN/12/03. The oncogene Meq was amplified by PCR and sequenced.

2. The isolates were shown to have a homology for the Meq gene of 99.1–99.8% with various isolates from China and 98.5–99.2% with isolates from Europe and the USA. Alignment analysis of the nucleotide sequences showed that nucleotide mutations at 5 different positions in the Meq gene displayed perfect regularity in MDVs circulating in the southern part of India, which could be considered as features of field MDVs recently prevalent in this area.

3. In addition, the mutation in the Meq gene at positions 251, 260 and 437 was unique and coincides with very virulent strains from China GX0101, GXY2 and a Hungarian strain ATE. The mutation at positions 283 and 300 was unique and coincides with the very virulent strain ATE of Hungary. There were also single nucleotide mutations at positions 155 (A–T), 369 (A–C), 462 (C–A) and 548 (C–T) observed in the isolate Ind/TN/12/03.

4. Phylogenetic analysis of Meq sequences revealed that field MDVs in this area evolved independently but have similarities with very virulent strains from China, and that Meq has more similarities with the very virulent Hungarian strain.

KEYWORDS:

• MDV
• very virulent
• highly virulent
• phylogeny

Acknowledgements

None of the authors has any financial or personal relationships that could inappropriately influence or bias the content of the paper. The authors are highly thankful to Tamil Nadu Veterinary and Animal Sciences University (TANUVAS), Chennai, for necessary funding and The Dean, Veterinary College and Research Institute, Namakkal, for providing facilities.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Tamil Nadu Veterinary and Animal Sciences University (TANUVAS) and Veterinary College and Research Institute.