Association of major histocompatibility complex antigens (BOLA-A) with AI bull progeny test results for mastitis, ketosis and fertility in Norwegian Cattle

Short Communication: New alleles at the BoLA-DQA1 locus in Holstein–Fresian cattle

Kułajaj, D., Pokorska, J., Ormian, M. and Dusza, M. 2015. Short Communication: New alleles at the BoLA-DQA1 locus in Holstein Fresian cattle. Can. J. Anim. Sci. 95: 161–164. The aim of the study was to analyze genetic polymorphism at locus BoLA-DQA1 in Polish Holstein-Friesian cattle, using next generation sequencing technology (Miseq sequencer – Illumina). In the studied cattle population we identified 14 alleles, of which three were determined for the first time (BoLA-DQA1*0106, BoLA-DQA1*3201, BoLA-DQA1*3301). The frequencies of these alleles were respectively: 0.0423, 0.0282, 0.0282. At locus BoLA-DQA1 the highest frequency was found for the BoLA-DQA1*10011 and BoLA-DQA1*0101 alleles and their frequencies were respectively: 0.3592 and 0.2606. The frequencies of other alleles identified in the studied population ranged from 0.0070 to 0.0704. The results obtained in this study indicate that the BoLA-DQA1 locus is highly polymorphic and new alleles are still identifiable.

Analysis of relationship between bovine lymphocyte antigen DRB3.2 alleles, somatic cell count and milk traits in Iranian Holstein population

The major histocompatibility complex (MHC) is a gene complex closely linked to the vertebrate immune system due to its importance in antigen recognition and immune response to pathogens. To improve our understanding of the MHC and disease resistance in dairy cattle, we gathered 5119 test day records of somatic cell count (SCC) and performance traits of 262 Holstein dairy cows to determine whether the DRB region of the MHC contains alleles that are associated with elevated SCC, milk yield, protein and fat percent of milk. To this purpose, genotyping of animals for DRB3 gene was investigated by polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP) assay. A two-step PCR was carried out so as to amplify a 284 base-pair fragment of exon 2 of the target gene. Second PCR products were treated with three restriction endonuclease enzymes RsaI, BstYI and HaeIII. Twenty-eight BoLA-DRB3 alleles were identified including one novel allele (*40). The results in general are in good accordance with allele frequencies of Holstein cattle populations reported by previous studies. Analyses of associations were modeled based on repeated measurement anova and generalized logistic linear methods for production traits and SCC data, respectively. The results of this study showed a significant relationship between the elevated SCC reflecting an increased probability of occurrence to subclinical mastitis and DRB3.2 allele *8 (p < 0.03). The results also revealed significant positive relationships of alleles*22 (p < 0.01) and allele*11 (p < 0.05) with milk fat percent as well as of alleles*24 (p < 0.03) and *22 (p < 0.05) with protein percent. The present study failed to find any association between milk yield and tested alleles. Because of the lack of consistency among results of similar studies, we suggest further investigations to determine the precise nature of these associations with the high polymorphic bovine MHC region to be performed based on haplotypes.

A critical analysis of disease-associated DNA polymorphisms in the genes of cattle, goat, sheep, and pig

Genetic variations through their effects on gene expression and protein function underlie disease susceptibility in farm animal species. The variations are in the form of single nucleotide polymorphisms, deletions/insertions of nucleotides or whole genes, gene or whole chromosomal rearrangements, gene duplications, and copy number polymorphisms or variants. They exert varying degrees of effects on gene action, such as substitution of an amino acid for another, shift in reading frame and premature termination of translation, and complete deletion of entire exon(s) or gene(s) in diseased individuals. These factors influence gene function by affecting mRNA splicing pattern or by altering/eliminating protein function. Elucidating the genetic bases of diseases under the control of many genes is very challenging, and it is compounded by several factors, including host x pathogen x environment interactions. In this review, the genetic variations that underlie several diseases of livestock (under monogenic and polygenic control) are analyzed. Also, factors hampering research efforts toward identification of genetic influences on animal disease identification and control are highlighted. A better understanding of the factors analyzed could be better harnessed to effectively identify and control, genetically, livestock diseases. Finally, genetic control of animal diseases can reduce the costs associated with diseases, improve animal welfare, and provide healthy animal products to consumers, and should be given more attention.

Study on the association of BoLA-DRB3.2 alleles with clinical mastitis in Norwegian Red cows

Genotyping of bovine leucocyte antigen DRB3.2 (BoLA-DRB3.2) in a total of 523 Norwegian Red (NR) cows from two groups selected for high protein yield and low clinical mastitis, respectively, identified 27 previously reported BoLA-DRB3.2 alleles across the groups. Significant differences in BoLA-DRB3.2 allele frequencies were found between the selection groups. Alleles *13, *18, *22 and *27 had a significantly higher frequency in cows selected for low clinical mastitis, while alleles *3, *9, *11 and *26 had a higher frequency in cows selected for high protein yield. Associations between BoLA-DRB3.2 alleles and clinical mastitis were analysed based on mastitis data from 741,072 first-lactation NR cows, of which 452 were genotyped. Alleles *22 and *26 were found to be associated with increased clinical mastitis, while alleles *7, *11, *18 and *24 had a favourable effect on mastitis resistance. Contradictory results from different studies investigating associations between BoLA-DRB3.2 alleles and mastitis indicate that future studies should focus on associations of mastitis with BoLA haplotypes rather than with single BoLA genes.

Association of Bovine Leukocyte Antigen (BoLA) DRB3.2 with Immune Response, Mastitis, and Production and Type Traits in Canadian Holsteins

Data collected from 328 Canadian Holsteins in a research herd at the University of Guelph were used to study associations among expression of bovine leukocyte antigen (BoLA) DRB3.2 alleles, immune response, mastitis resistance via somatic cell counts (SCC), and clinical mastitis, as well as to extend these results to production and type traits. Accordingly, groups of cows were evaluated in vivo for both the antibody-mediated immune response (AMIR) and the cell-mediated immune response (CMIR), which generally predominate in responses to extracellular and intracellular pathogens, respectively. Of note was that associations between BoLA DRB3.2 alleles and immune responses tended to be in the opposite sign for the 2 AMIR and CMIR traits examined. For example, alleles DRB3.2*3 and *24 were associated with higher AMIR but lower CMIR, whereas allele *22 was associated with lower AMIR but higher CMIR. This finding is in agreement with the hypothesis that both traits are genetically independent and represent opposing type 1 and type 2 immune responses. Additionally, BoLA DRB3.2*3 and *11 were associated with lower SCC, whereas alleles *22 and *23 were associated with higher SCC. Finally, allele DRB3.2*3 was also associated with less clinical mastitis, whereas allele *8 was associated with higher mastitis risk. Allele *3 was of particular relevance because it was associated with increased antibodies, as well as reduced mastitis and SCC. This could be due to an indirect relationship between the ability to produce a high antibody response and enhanced defense against intrammamary infections caused by extracellular pathogens. Consequently, the BoLA DRB3.2*3 allele should be investigated further as a candidate for resistance to some types of intramammary infections, the important caveat being its association with lower CMIR, particularly with one of the test antigens used to evaluate delayed-type hypersensitivity. The results of associations between BoLA DRB3.2 and production traits were, in some cases, antagonistic in that BoLA DRB3.2 alleles *11 and *23, which are associated with increased production traits, were associated with lower and higher SCC, respectively. Collectively, these findings advocate the use of alleles *3, *23, and *22 as reference points for more detailed mechanistic studies. This does not imply that genetic selection for mastitis resistance should be based on BoLA alleles, but that information on a variety of genes may aid in identification and selection for improved health.

In Vitro Peripheral Blood Mononuclear Cell Proliferation in a Crossbred Cattle Population

Immune function measured by Staphylococcus aureus- and phytohemagglutinin- (PHA-) induced cell proliferation was assessed in a population of 445 genetically defined, F2 and backcross Charolais-Holstein crossbred cattle when the animals were approximately 5 mo of age. Variation in Staph. aureus-induced, PHA-induced, and control proliferation [peripheral blood mononuclear cell (PBMC) and media only] was observed at d 2, 3, 4, 5, 9, and 10 of in vitro culture. The levels of Staph. aureus-induced, PHA-induced, and control proliferation were strongly positively correlated between days of culture within-assay (e.g., between d 2 and d 3 or between d 4 and d 5). Responses were also positively correlated when the same individuals were resampled and the assay repeated within 3 mo. Analyses fitting linear mixed models using REML showed that Staph. aureus-induced and PHA-induced proliferation was significantly associated with control proliferation and the year of birth. The age of the animal at sampling influenced only Staph. aureus-induced proliferation, with Staph. aureus-induced proliferation increasing with the age of the animal. Control proliferation was influenced by a sex x cross interaction, although in this study, sex was confounded by management, as female cattle were housed and reared differently from male cattle. All 3 measures of immune function were influenced by sire, demonstrating that these traits are partially under genetic control, and indicating that it may ultimately be possible to identify quantitative trait loci for these measures of immunity.

Multi-primer target PCR for rapid identification of bovine DRB3 alleles

Multi-primer target polymerase chain reaction (MPT-PCR) is a rapid method for the identification of specific BoLA-DRB3 alleles. In a single PCR reaction, the presence of two alleles associated with increased risk, DRB3.2*23 (DRB3*2701-2703, 2705-2707) and decreased risk, DRB3.2*16 (DRB3*1501, 1502), of mastitis in Canadian Holstein can be detected. Two outer primers amplify exon 2 of DRB3. Simultaneously, two inner, allele-specific primers amplify individual alleles. Initially, 40 cows previously typed by PCR-restriction fragment length polymorphism (PCR-RFLP) were genotyped using the multi-primer approach. An additional 30 cows were first genotyped by multi-primer target PCR, then by PCR-RFLP. All animals were correctly identified and there were no false positives. This technique can readily be modified to identify other BoLA alleles of interest.

Mammary gland immunology around parturition. Influence of stress, nutrition and genetics

Adequate immune functions are essential for the defence against udder infections. Detailed knowledge about the immune response and important defence factors is essential in order to find new ways for the prevention and treatment of udder infections leading to mastitis. Work should be concentrated on ways of minimising the negative influence on immune functions and/or ways of stimulating these functions, especially during periods of immune suppression. A depression of important immune functions has been reported around parturition and there is a higher prevalence of clinical mastitis and other diseases during this period. Immunosuppression is often associated with high levels of glucocorticoids in blood, a common finding around parturition and during stressful conditions. A number of stressors are present around calving, e.g. parturition, onset of lactation and changes in feeding and management regimes. Adequate management including feeding strategies and routines are important for the immune functions. Metabolic stress as well as deficiencies in vitamins and minerals around parturition and during the first month of lactation can have a negative influence on the immune functions and thereby increase the risks for udder infections and mastitis. There seem to be a genetic variability in certain immune functions among periparturient cows. This might indicate a possibility to find markers for genetic selection of individuals with a well-developed immune system without negative effects on milk productivity.

Rainbow trout offspring with different resistance to viral haemorrhagic septicaemia

To study immunological and immunogenetical parameters related to resistance against viral haemorrhagic septicaemia (VHS), attempts to make gynogenetic strains of rainbow trout selected for high and low resistance to VHS were initiated in 1988. The first gynogenetic generation of inbreeding resulted in the more resistant offspring E8 and the low resistance offspring K3; the K3 offspring having the same high mortality as the susceptible reference strain of outbred trout in infection trials. A second gynogenetic generation derived from the E8 strain resulted in some low resistance offspring, and two gynogenetic families in which all, or nearly all, fish survived challenge with VHS virus. In this study, an attempt to associate the distribution of different MHC class II genotypes with low and high resistance gynogenetic offspring was performed. Two different MHC haplotypes could be distinguished, and in both low and high resistance families all three genotypes were found, which could be explained by the fact that the mother fish carried the heterozygous genotype. Although no significant differences in MHC II genotypes were found between the high and low resistance offspring, a significantly different distribution of haplotypes in the low resistance offspring was observed, that could not be explained by a one- or two-locus model.

Alteration in immune responsiveness during the peripartum period and its ramification on dairy cow and calf health

Substantial evidence indicates that innate and acquired defense mechanisms are lowest from 3 wk precalving to 3 wk postcalving. This lowered responsiveness includes aspects of systemic and mammary gland immunity that may account, at least in part, for the increased incidence of peripartum disease. The physical and metabolic stresses of pregnancy, calving, and lactation may contribute to this decrease in host resistance and the subsequent increase in disease incidence. However, variation among cows in their host resistance mechanisms suggests that genotype and phenotype may possibly be used to identify cows that are able to mount beneficial immune responses over the periparturient period. Our own studies suggest that cows may be categorized as high or low responders based on the peripartum antibody responses to ovalbumin and Escherichia coli J5. Low responders were hyporesponsive to these test antigens and had a higher incidence of peripartum diseases, particularly mastitis. In many species, a functional link exists between the immune and endocrine systems, and, during periods of stress or physical injury, neuropeptides and neuroendocrine hormones function as immunomodulators. Initial investigations of peripartum cows reveal positive relationships between growth hormone kinetics and profiles of antibody response. Whether hormone fluctuations during the periparturient period are responsible for the alterations observed in immune responsiveness remains uncertain.

Analysis of associations between major histocompatibility complex (BoLA) class I haplotypes and subclinical mastitis of dairy cows

The associations between BoLA class I haplotypes and subclinical mastitis were investigated using information on 333 cows from three different breeds and crossbreeds from 14 dairy herds in Denmark. Somatic cell count and bacteriological status were used as markers for subclinical mastitis. Associations between BoLA class I haplotypes and IMI status were also determined. The association between BoLA class I haplotypes and subclinical mastitis was weak. The A10(W50), A11, A12(A30), A16, A19(A6), A21, A26, and A31(A30) alleles were associated with different markers of subclinical mastitis. Susceptibility or resistance to the two bacteria categories was associated with different alleles. This study indicated that BoLA antigens may be involved in resistance to mastitis and that resistance may be specific for a particular pathogen.