Newcastle disease (ND) is a global threat to domestic poultry, especially in rural areas of Africa and Asia, where the loss of entire backyard local chicken flocks often threatens household food security and income. To investigate the genetics of Ghanaian local chicken ecotypes to Newcastle disease virus (NDV), in this study, three popular Ghanaian chicken ecotypes (regional populations) were challenged with a lentogenic NDV strain at 28 days of age. This study was conducted in parallel with a similar study that used three popular Tanzanian local chicken ecotypes and after two companion studies in the United States, using Hy-line Brown commercial laying birds. In addition to growth rate, NDV response traits were measured following infection, including anti-NDV antibody levels [pre-infection and 10 days post-infection (dpi)], and viral load (2 and 6 dpi). Genetic parameters were estimated, and two genome-wide association study analysis methods were used on data from 1,440 Ghanaian chickens that were genotyped on a chicken 600K Single Nucleotide Polymorphism (SNP) chip. Both Ghana and Tanzania NDV challenge studies revealed moderate to high (0.18 – 0.55) estimates of heritability for all traits, except viral clearance where the heritability estimate was not different from zero for the Tanzanian ecotypes. For the Ghana study, 12 quantitative trait loci (QTL) for growth and/or response to NDV from single-SNP analyses and 20 genomic regions that explained more than 1% of genetic variance using the Bayes B method were identified. Seven of these windows were also identified as having at least one significant SNP in the single SNP analyses for growth rate, anti-NDV antibody levels, and viral load at 2 and 6 dpi. An important gene for growth during stress, CHORDC1 associated with post-infection growth rate was identified as a positional candidate gene, as well as other immune related genes, including VAV2, IL12B, DUSP1, and IL17B. The QTL identified in the Ghana study did not overlap with those identified in the Tanzania study. However, both studies revealed QTL with genes vital for growth and immune response during NDV challenge. The Tanzania parallel study revealed an overlapping QTL on chromosome 24 for viral load at 6 dpi with the US NDV study in which birds were challenged with NDV under heat stress. This QTL region includes genes related to immune response, including TIRAP, ETS1, and KIRREL3. The moderate to high estimates of heritability and the identified QTL suggest that host response to NDV of local African chicken ecotypes can be improved through selective breeding to enhance increased NDV resistance and vaccine efficacy.

新城疫（ND）是对家禽的全球威胁，特别是在非洲和亚洲的农村地区，那里整个后院当地鸡群的流失经常威胁到家庭粮食安全和收入。为了研究加纳当地鸡生态型对新城疫病毒（NDV）的遗传，在这项研究中，对28天大的加纳鸡生态型（区域种群）进行了抗性NDV菌株的攻击。该研究与一项相似的研究同时进行，该研究使用了三种流行的坦桑尼亚当地鸡生态型，并在美国进行了两次同伴研究后，使用海兰布朗商业产蛋鸡。除生长速度外，还测量了感染后的NDV反应性状，包括抗NDV抗体水平[感染前和感染后10天（dpi）]，和病毒载量（2和6 dpi）。估计了遗传参数，并使用两种全基因组关联研究分析方法对来自1,440只加纳鸡的数据进行了基因分析，这些鸡在鸡600K单核苷酸多态性（SNP）芯片上进行了基因分型。加纳和坦桑尼亚NDV挑战研究均显示，所有性状的遗传力估计均中等至较高（0.18 – 0.55），但病毒清除率除外，因为坦桑尼亚遗传型的遗传力估计与零没有差异。对于加纳研究，从单SNP分析和20个基因组区域（使用贝叶斯B方法解释了超过1％的遗传变异）中确定了12个用于NDV生长和/或对NDV响应的定量性状位点（QTL）。在单个SNP分析中，这些窗口中有七个还被确定具有至少一个重要的SNP，抗NDV抗体水平以及2和6 dpi时的病毒载量。与应激后生长速率相关的CHORDC1是应激过程中生长的重要基因，被确定为位置候选基因，以及其他免疫相关基因，包括VAV2，IL12B，DUSP1和IL17B。加纳研究确定的QTL与坦桑尼亚研究确定的QTL不重叠。然而，两项研究均揭示了QTL具有在NDV攻击过程中对生长和免疫应答至关重要的基因。坦桑尼亚的平行研究显示，在6 dpi时，病毒载量在24号染色体上有一个重叠的QTL。这个QTL区域包括与免疫反应相关的基因，包括TIRAP，ETS1和KIRREL3。