Complete nucleotide sequence analysis of the oncogene "Meq" from serotype 1 Marek's disease virus isolates from India.

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.

Pathotyping of recent Indian field isolates of Marek's disease virus serotype 1.

A study was undertaken to assess the virulence of Marek's disease virus (MDV) serotype 1 field isolates obtained from poultry flocks of southern part of India. Five representative MDV serotype 1 strains were isolated from eighty-six blood samples collected from fifteen farms. Three out of five isolates which were free from avian leukosis virus (ALV) and reticuloendotheliosis virus (REV) were adapted in chicken embryo fibroblast (CEF) culture and designated as Ind/TN/11/01, Ind/KA/12/02 and Ind/TN/12/03. Pathotyping assay was conducted in two trials. In the first trial, non-vaccinated chickens were challenged (trial I), while in second trial, two types of vaccinated chickens along with non-vaccinated controls were challenged (trial II). Birds inoculated with field isolate Ind/TN/12/03 had very low body (75.34 ± 3.04 g 15 days post infection (dpi)) and bursa Fabricii weight (1.64 ± 0.06 at 15 dpi) when compared to those inoculated with the other two isolates (Ind/TN/11/01 and Ind/KA/12/02) and uninoculated controls (body weight 111.33 ± 1.30 g and bursa Fabricii weight 4.33 ± 0.11 15 dpi). Incidence of early mortality syndrome (53%) and lymphoma (86%) induced by Ind/TN/12/03 was comparable with very virulent strains published elsewhere. In protection test, the percentage of Marek's disease (MD) incidence induced by Ind/TN/12/03 was 57.5% and 25% in monovalent and bivalent vaccine inoculated birds respectively compared to uninoculated control (100%). Based on the above findings in pathotyping experimental trials with a supportive evidence of histopathological observations, isolate Ind/TN/12/03 was considered as very virulent MDV and other two isolates were considered as virulent MDVs.

Ground beetle, Opatroides frater (Coleoptera) as natural intermediate host for the poultry tapeworm, Raillietina cesticillus.

Poultry farms in and around Namakkal with a history of tapeworm infection were surveyed for the presence of beetles which could act as intermediate host for the tapeworms. Beetles collected from different poultry farms with suspected tapeworm infection were examined for the presence of metacestode stage of the parasite. A total of 1,880 beetles were collected from 12 poultry farms with suspected tapeworm infection to study the vector potentiality. Out of these, 205 beetles (10.9 %) from nine farms were found to harbour cysticercoids. The percentage of cysticercoid infection in beetles was 8.24, 10.34 and 16.66 % respectively in three different surveys. The beetles harbouring the cysticercoids were identified as Opatroides frater, which may be a natural intermediate host for Raillietina cesticillus. Infection free young chicks (4 weeks old) were experimentally infected with specific number of cysticercoids and prepatent period of tapeworms was found to be between 12 and 13 days. Gravid segments were expelled between 3 and 4 p.m. consistently. The results of this study would help to formulate suitable control measures against the above tapeworm infection.