Host Genetics and Vaccine Efficacy: Global Gene Expression Differences Induced by Vaccine and MDV in MD Resistant and Susceptible Chickens Based on Next-Gen RNA-Seq Reads

Marek’s disease (MD), a herpesvirus-induced disease of poultry, has been controlled primarily by vaccination. This study aimed to compare the protective efficacy of two commonly used MD vaccines, Herpesvirus of Turkey (HVT) and CVI988/Rispens, in a MD resistant and a susceptible line of chickens. The experiment consisted of five treatment groups per line, HVT, Rispens, MDV, HVT+MDV, and Rispens+MDV. No birds in the HVT or Rispens groups developed MD in either line. Almost all of the birds in the MDV groups of both lines developed MD (94% and 100%, respectively). The MDV group of the resistant line, however, survived significantly more days than the susceptible line (35±4 vs. 18±2, respectively). HVT and Rispens conveyed comparable protection in the resistant chickens (PI = 91% vs. 87%, respectively) but significantly different protection in the susceptible chickens (PI = 25% vs. 80%, respectively). The spleen RNA samples at 5, 10, and 21 days post infection (DPI) from each treatment group were deeply sequenced. On average, there were more than 207 million reads that passed quality control filter per sample, more than 94% of the reads with Phred quality scores ≥30. Preliminary analysis of the RNA reads of all treatment groups suggests that global gene expression differed between the MD resistant and susceptible lines of chickens, and HVT as well as CVI988/Rispens induced differential gene expression with or without MDV challenge at 5, 10, and 21 DPI in both lines. It is anticipated that these data will provide insight on host genes and pathways that modulate vaccine immunity and protective efficacy.