Genetic Parameter Estimation and Genome Wide Association Study for NDV Response in Chickens

Exotic Newcastle disease causes up to 80% mortality in chickens in developing countries where the virus is endemic, limiting the production of eggs and meat.  Genetic resistance, complementary to vaccination in a disease prevention program, has the potential to be an important tool to reduce the impact of NDV.

The experiment was replicated across three hatches of a commercial egg-laying line, Hy-Line Brown.  Inoculation with NDV, La Sota strain, occurred on day 21 by an ocular-nasal route.  Body weights, blood, and tears were collected throughout the study.  Virus load was estimated from viral mRNA level in tears by qRT-PCR; systemic antibody response to NDV in serum was measured by ELISA. Genomic DNA was isolated for genotyping via Affymetrix 600K chicken SNP array.

We hypothesize that many genes regulate NDV resistance in chickens and aim to identify genetic markers associated with NDV resistance (reduced viral load, high antibody titer) so these markers can be applied in genetic selection.

Analyses of viral RNA and antibody levels have confirmed response of challenge groups to the virus and lack of response in control groups.

ASREML estimated heritabilities of 0.38, 0.29, 0.04, and 0.07 for hatch weight, day 31 weight, 0dpi and 10dpi antibody levels, respectively.  GWAS will be performed using GenSel to determine associations between genotype and phenotype data.  This study will address important issues including correlations between NDV resistance and production traits such as growth.

Support: USAID Feed the Future Innovation Lab for Genomics to Improve Poultry, Hy-Line International, and Hatch project #5357