Genetic Polymorphisms of Chicken Antiviral Mx1 and TVB Genes in Indigenous and Giriraja Chicken

Background: Recent developments in molecular genetics lead to addressing certain poultry diseases via breeding for disease resistance. The present study was carried to identify and compare the genetic polymorphism in Chicken Mx1 and TVB genes among the indigenous and Giriraja chicken using PCR-RFLP technique. Methods: Blood samples were collected from 50 indigenous and 50 Giriraja birds and DNA isolation was done by Phenol: Chloroform: Isoamyl alcohol method. PCR amplification of Chicken Mx1 (exon 14) and Chicken TVB (exon 3) genes was carried out followed by RFLP analysis. Result: PCR product sizes of 301 bp and 303 bp of Mx1 and TVB genes, respectively were successfully amplified. RFLP analysis of Mx1 gene with Hyp8I restriction enzyme revealed three genotypes AA, AB and BB. In indigenous birds genotypic frequencies of AA, AB and BB were 0.314, 0.493 and 0.194, respectively and gene frequencies were 0.56 and 0.44 for alleles A and B, respectively. In Giriraja birds, genotypic frequencies for AA, AB and BB were 0.27, 0.499 and 0.23, respectively and gene frequencies were 0.52 and 0.48 for alleles A and B, respectively. RFLP analysis of TVB gene with NlaIII restriction enzyme revealed two genotypes viz., AA and AB. In indigenous birds genotypic frequencies of AA and AB were 0.81 and 0.18, respectively and gene frequencies were 0.9 and 0.1 for alleles A and B, respectively. In Giriraja birds genotypic frequencies for AA and AB were 0.774 and 0.211, respectively and gene frequencies were 0.88 and 0.12 for alleles A and B, respectively.

Genetic Markers Associated with Field PRRSV-Induced Abortion Rates

In gilts and sows, the more severe clinical manifestation of porcine reproductive and respiratory syndrome virus (PRRSV) occurs in late gestation and can result in up to a 40% abortion incidence. Despite the known genetic component in resilience to PRRSV, there is scarce information regarding the abortive outcome of this disease. We tested the relationship between eight molecular markers (six from published studies and two identified in the present study in the HDAC6 gene) and the probability of abortion during a PRRSV outbreak, using data from two commercial Landrace x Large White sow farms with an incidence of abortion of 35% and 17%. From the markers tested, USP18_-1533G>A did not segregate in these populations, and CD163_c.3534C>T and HDAC6_g.2360C>T did not affect the abortion rate. In contrast, the minor allele of two markers in SSC4 (WUR1000125 in GBP1 and rs340943904 in GBP5), which lower viremia in growing pigs, and the major alleles of CD163_rs1107556229 and HDAC6_rs325981825 were associated with a lower probability of abortion during PRRSV outbreaks. The more striking result was for the MX1 gene, where the odds ratio of aborting versus not aborting was nine times lower in the sows homozygous for a 275-bp insertion than in the other genotypes. Interactions between markers were not relevant. All together, we bring here the first evidence that mutations in the host genome can predispose or protect from complete reproductive failure in sows infected with PRRSV.

Genetic variations of the bovine MX1 and their association with mastitis

The primary agent of mastitis is a wide spectrum of bacterial strains; however, viral-related mastitis has also been reported. The MX dynamin-like GTPase 1 (MX1) gene has been demonstrated to confer positive antiviral responses to many viruses, and may be a suitable candidate gene for the study of disease resistance in dairy cattle. The present study was conducted to investigate the genetic diversity of the MX1 gene in Chinese cattle breeds and its effects on mastitis in Holstein cows. First, polymorphisms were identified in the complete coding region of the bovine MX1 gene in 14 Chinese cattle breeds. An association study was then carried out, utilizing polymorphisms detected in Holstein cows to determine the associations of these single nucleotide polymorphisms (SNPs) with mastitis. We identified 13 previously reported SNPs in Chinese domestic cattle and four of them in Holstein cattle. A novel 12 bp indel was also discovered in Holstein cattle. In addition, haplotype frequencies and linkage disequilibrium of four SNPs detected in Holstein cows were investigated. Analysis of these four SNPs in Chinese Holstein cows revealed two SNPs (g.143181370 T&gt;C and g.143182088 C&gt;T)<br /> significantly (P &lt; 0.05) associated with somatic cell score (SCS). The results indicated that SNPs in the MX1 gene might contribute to the variations observed in the SCS of dairy cattle. Therefore, implementation of these two mutations in selection indexes of the dairy industry might be beneficial by favouring the selection individuals with lower SCS.

Nucleotide sequence analysis of Mx1 gene in Japanese quail

During the process of increasing production potential of poultry, other economically important traits like disease resistance are neglected and ultimately leading to decrease in quality food production. The poultry health management is important due to emergence of highly pathogenic diseases like Avian Influenza. Mx1 gene has been reported to provide resistance against avian influenza virus in chicken. Therefore, present research work was focused to identify the genetic variation of Mx1 gene in Japanese quail. Total three fragments viz. Frag-I of 185 bp (Exon 3 region), Frag-II of 161 bp (Exon 7 region) and Frag-III of 176 bp (Exon 13 region) of Mx1 gene in 170 Japanese quail birds were amplified and screened for polymorphism by PCR-SSCP technique. All the three fragments were found to be monomorphic which was confirmed by dideoxy nucleotide sequencing. Comparative analysis of Mx1 sequence of Japanese quail by MegAlign programme of DNASTAR showed 100% homology with common quail and more than 80% homology with Rhode Island Red and Silki chicken breeds.