Rapid Communication: Subclinical bovine respiratory disease – loci and pathogens associated with lung lesions in feedlot cattle1

Abstract

Bovine respiratory disease (BRD) is an economically important disease of feedlot cattle that is caused by viral and bacterial pathogen members of the BRD complex. Many cases of subclinical BRD go untreated and are not detected until slaughter, when lung lesions are identified. The objectives of this study were to identify which BRD pathogens were associated with the presence of lung lesions at harvest and to identify genomic loci that were associated with susceptibility to lung lesions as defined by consolidation of the lung and/or the presence of fibrin tissue. Steers from a Colorado feedlot ( = 920) were tested for the presence of viral and bacterial pathogens using deep pharyngeal and mid-nasal swabs collected on entry into the study. Pathogen profiles were compared between cattle with or without lung consolidation (LC), fibrin tissue in the lung (FT), a combination of LC and FT in the same lung (lung lesions [LL]), and hyperinflated lungs (HIF) at harvest. Genotyping was conducted using the Illumina BovineHD BeadChip. Genomewide association analyses (GWAA) were conducted using EMMAX (efficient mixed-model association eXpedited), and pseudoheritabilities were estimated. The pathogen profile comparisons revealed that LC ( = 0.01, odds ratio [OR] = 3.37) and LL cattle ( = 0.04, OR = 4.58) were more likely to be infected with bovine herpes virus-1 and that HIF cattle were more likely to be infected with spp. ( = 0.04, OR = 4.33). Pseudoheritability estimates were 0.25 for LC, 0.00 for FT, 0.28 for LL, and 0.13 for HIF. Because pseudoheritability for FT was estimated to be 0, GWAA results for FT were not reported. There were 4 QTL that were moderately associated ( < 1 × 10) with only LC, 2 that were associated with only LL, and 1 that was associated with LC and LL. Loci associated with HIF included 12 that were moderately associated and 3 that were strongly associated (uncorrected P < 5 × 10-7). A 24-kb region surrounding significant lead SNP was investigated to identify positional candidate genes. Many positional candidate genes underlying or flanking the detected QTL have been associated with signal transduction, cell adhesion, or gap junctions, which have functional relevance to the maintenance of lung health. The identification of pathogens and QTL associated with the presence of lung abnormalities in cattle exhibiting subclinical BRD allows the identification of loci that may not be detected through manifestation of clinical disease alone.

Non-specific protection from respiratory tract infections in cattle generated by intranasal administration of an innate immune stimulant

“…Another intriguing finding was the stimulatory effect of local activation of innate immune responses in the upper respiratory tract on systemic humoral immune responses to several key bacterial pathogens often harbored sub-clinically in the upper respiratory tract of cattle [69]. Thus, in animals treated with a single intranasal LTC administration, we observed significant increases in IgG responses to Mannheimia, Histophilus, and Pasteurella, consistent with activation of specific T cell and B cell responses to these pathogens.…”

Genome-wide detection of signatures of selection in indicine and Brazilian locally adapted taurine cattle breeds using whole-genome re-sequencing data

“…Five genomic regions overlapped between the candidate sweep regions of the within-population and cross-population DCMS statistics (BTA4:101600000–101,650,000, BTA5:3700000–3,750,000, BTA9:98650000–98,700,000, BTA11:22300000–22,350,000, and BTA11:53900000–53,950,000). When inspecting in detail, the region on BTA4:101600000–101,650,000 harbored two quantitative trait locus (QTL) with functions related to the bovine respiratory disease [ 22 ] and body condition score [ 23 ]. The remaining four regions have not been associated with any QTL in cattle so far, however, they were found to be in close vicinity (~ 15 to 237 kb) with specific QTLs for beef cattle production traits.…”

Experimental challenge with bovine respiratory syncytial virus in dairy calves: bronchial lymph node transcriptome response

“…Therefore, measuring host gene expression levels may prove to be a more accurate way of diagnosing BRD than by the observation of clinical signs of the disease. This would be hugely beneficial to the global agricultural industry as sub-clinical BRD which remains undiagnosed is almost as prevalent in healthy cattle as BRD is among cattle which are diagnosed with respiratory disease and treated for BRD 39 . Although it would clearly not be possible to measure host gene expression in bronchial lymph node tissue in live calves if a small set of diagnostic genes are also perturbed in expression in white blood cells or nasal fluid, these more accessible media could be used as “liquid biopsies” for the future diagnosis of subclinical respiratory infections.…”