Role of chicken astrovirus as a causative agent of gout in commercial broilers in India.

Several outbreaks of gout were reported in commercial broilers in India during 2011 and 2012, causing up to 40% mortality in the birds. Gross and histopathological observations confirmed gout. Quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) analysis from kidney samples of gout-affected birds indicated the presence of chicken astrovirus (CAstV) in 41.7% of cases and a mixed infection of CAstV and avian nephritis virus (ANV) in 36.4% of cases. CAstV isolated from gout-affected kidneys by inoculating embryonated specific pathogen free (SPF) eggs showed dwarfing in embryos and a cytopathic effect in chicken embryo kidney cells. Inoculation of 1-day-old SPF and broiler chicks with CAstVs caused gout and mortality between 4 and 10 days post inoculation. Virus isolation and qRT-PCR analysis showed the presence of only CAstV in inoculated chicks. Sequence analysis of capsid genes indicated a major group of Indian CAstVs that displayed 92.0 to 99.2% intergroup amino acid identity and 83.9 to 90.4% identity with subgroup Bi CAstVs of UK origin. We designated this group Indian Bi. Analysis of the partial polymerase amino acid sequences of our isolates indicated two groups of CAstVs (Indian 1 and 2) that displayed 90.2 to 95.5% amino acid identity between them. We thus report for the first time that, in addition to infectious bronchitis virus and ANV, CAstVs are a causative agent of gout.

Molecular characterization of velogenic viscerotropic Ranikhet (Newcastle) disease virus from different outbreaks in desi chickens.

AIM: Diagnosis of velogenic viscerotropic Ranikhet disease from six different flocks of desi chicken in and around Mumbai by gross and histopathological examination, isolation of virus and molecular methods. MATERIALS AND METHODS: A total of 25 carcasses (varying between 2 and 6 carcasses from each flock) of six different flocks of adult desi chicken were subjected to necropsy examination for diagnosis of the disease during the span of a year (2014-2015). After thorough gross examination, the tissue samples were collected and processed for virus isolation and histopathological examination. The 20% tissue homogenate was inoculated into 9-day-old specific pathogen free (SPF) embryonated eggs. Mean death time (MDT) of embryos after inoculation and intracerebral pathogenicity index (ICPI) were used to judge velogenic nature of the virus. Newcastle disease virus (NDV) was isolated from six cases and confirmed by reverse transcriptase-polymerase chain reaction (RT-PCR) targeting the partial fusion protein gene of the viral genome. RESULTS: A total of 25 carcasses (varying between 2 and 6 carcasses from each flock) of six different flocks of desi chicken were presented for postmortem examination to Department of Veterinary Pathology, Bombay Veterinary College, Parel, Mumbai during 2014-2015. The gross and histopathological examination revealed lesions suggestive of viscerotropic velogenic form of the Newcastle disease (ND). The 20% tissue homogenate was inoculated into 9-day-old embryonated eggs from SPF chicken. NDV was isolated from six cases and confirmed by RT-PCR targeting the partial fusion protein gene. MDT of all the isolates was <60 h which indicated velogenic nature of the virus. ICPI of the isolates ranged between the 1.63 and 1.78. In four out of six outbreaks concurrent moderate to heavy infection of Ascardii galli in one flock and Railetina spp. in three flocks was also noted. In this study, viscerotropic velogenic form of ND was confirmed in all six outbreaks by gross and microscopic examination, virus isolation and RT-PCR. CONCLUSIONS: In this study, viscerotropic velogenic form of ND was confirmed in all six outbreaks by gross and microscopic examination, virus isolation and RT-PCR. Nowadays, vaccine strains Lasota, B1 and F strains are used widely in India to control the infection of NDV. However, virulent NDV strains are still isolated frequently in the birds under backyard and also in commercial venture which demonstrates that NDV remains an on-going threat to commercial as well as backyard poultry flocks.

Prevalence of chicken infectious anaemia virus (CIAV) in commercial poultry flocks of northern India: a serological survey.

Globally, the chicken infectious anaemia virus (CIAV) has gained much importance as an immunosuppressive and economically important emerging pathogen of poultry. In recent years, the virus has been detected and isolated from poultry flocks of India. The present study reports the first sero-epidemiological investigation of the presence of CIAV infection in poultry flocks of the country. A total of 404 serum samples were collected from chicken flocks of eleven poultry farms, which contain a total of 0.34 million birds from four Northern states, suspected of having chicken infectious anaemia (CIA). Screening of the sera samples using a commercially available enzyme-linked immunosorbent assay (ELISA) kit revealed 351 serum samples (86.88%) to be positive for CIAV antibodies. A high CIAV prevalence rate recorded in the present investigation, along with earlier virus detection reports, indicates the widespread distribution of the virus and that CIAV should be considered an economically important poultry pathogen affecting poultry industry of India. Extensive nationwide epidemiological studies are suggested for revealing the economic impact of CIA and to initiate further research along with devising and adapting suitable prevention and control strategies especially the use of suitable vaccines for safeguarding poultry health and production in the country.

Response of naked neck (Nana) and normal (nana) broiler chickens to dietary energy levels in a subtropical climate.

1. The comparative response of naked neck (Nana) broiler chickens and their normally feathered (nana) full sibs to varied dietary energy levels was assessed under natural ambient conditions in a subtropical climate in two separate trials, one in winter (19.0 to 26.0 degrees C) and the other in summer (28.1 to 37.4 degrees C). 2. The chickens were fed on diets with 10.9, 11.5 or 12.1 MJ ME/kg and with a constant protein content of 200 g/kg from 1 to 42 d of age. 3. Both genotypes showed similar body weight, food intake and food conversion efficiency at 42 d of age. Body weight and food conversion efficiency improved on the diet with the highest energy content. 4. Apparent retention (AR) of crude protein (CP) was higher in nana chickens than in their Nana sibs in the winter trial, while no differences were observed for AR of dry matter (DM), crude fibre (CF), ether extract (EE) or calcium. In the summer trial, no difference in nutrient retention was seen between the genotypes. Increasing dietary energy had a positive influence on AR of DM, CP and EE. 5. The relative weights of feathers and skin were lower in Nana chickens than in their normal counterparts. Ready-to-cook yields were greater at the high dietary energy content, while abdominal fat increased with increasing energy content. Nana chickens had more skin protein and less fat in breast muscle and skin than their normal sibs in the summer trial. 6. It was concluded that the Nana broiler chickens showed similar performance and did not differ in dietary energy requirements in comparison to their nana sibs under natural ambient conditions in a subtropical climate.