Identification of polymorphisms in the bovine collagenous lectins and their association with infectious diseases in cattle.

Infectious diseases are a significant issue in animal production systems, including both the dairy and beef cattle industries. Understanding and defining the genetics of infectious disease susceptibility in cattle is an important step in the mitigation of their impact. Collagenous lectins are soluble pattern recognition receptors that form an important part of the innate immune system, which serves as the first line of host defense against pathogens. Polymorphisms in the collagenous lectin genes have been shown in previous studies to contribute to infectious disease susceptibility, and in cattle, mutations in two collagenous lectin genes (MBL1 and MBL2) are associated with mastitis. To further characterize the contribution of variation in the bovine collagenous lectins to infectious disease susceptibility, we used a pooled NGS approach to identify short nucleotide variants (SNVs) in the collagenous lectins (and regulatory DNA) of cattle with (n = 80) and without (n = 40) infectious disease. Allele frequency analysis identified 74 variants that were significantly (p < 5 × 10-6) associated with infectious disease, the majority of which were clustered in a 29-kb segment upstream of the collectin locus on chromosome 28. In silico analysis of the functional effects of all the variants predicted 11 SNVs with a deleterious effect on protein structure and/or function, 148 SNVs that occurred within potential transcription factor binding sites, and 31 SNVs occurring within potential miRNA binding elements. This study provides a detailed look at the genetic variation of the bovine collagenous lectins and identifies potential genetic markers for infectious disease susceptibility.

Duodenitis-Proximal Jejunitis in Horses After Experimental Administration of Clostridium difficile Toxins.

BACKGROUND: Duodenitis-proximal jejunitis (DPJ) is an acute sporadic gastrointestinal disorder of horses of unknown cause. HYPOTHESIS/OBJECTIVES: We hypothesize that Clostridium difficile toxins are involved in the pathogenesis of DPJ in horses. The objective of this study was to determine whether experimentally delivered C. difficile toxins cause clinical signs and histologic lesions similar to those of naturally occurring DPJ. ANIMALS: Six healthy mature mixed breed horses. METHODS: Experimental study: animal model of animal disease. Fasted horses were administered crude C. difficile toxins via gastroscopy and monitored for up to 48 hour. Blood was collected for complete blood cell count, biochemistry profile, and plasma fibrinogen assay, and abdominal fluid was collected for cytologic analysis and total solids before and after toxin administration. Physical examination and abdominal ultrasonography were performed throughout the study period. Tissues were collected from the gastrointestinal tract and processed for routine histologic analysis, and lesions were scored. RESULTS: Clinical signs were observed in 2 of 6 horses that are typical although not specific for horses with naturally occurring DPJ. Histopathologic lesions were observed in 6 of 6 horses and were similar to those reported in horses with naturally occurring DPJ. Two horses were severely affected. CONCLUSIONS AND CLINICAL IMPORTANCE: Duodenitis-proximal jejunitis is likely a syndrome with multiple causes that result in the same clinical and pathologic findings, and our data suggest that the toxins of C. difficile represent one cause of this syndrome. Toxin dose and variation in individual animal susceptibility might affect the clinical signs and lesions after administration of C. difficile toxins.

Epitheliocystis in lake trout Salvelinus namaycush (Walbaum) is associated with a ß-proteobacteria.

Lake trout Salvelinus namaycush (Walbaum) raised for stocking experienced yearly (2011-13) winter epizootics of epitheliocystis. Affected fish were dispersed on the bottom of the tank, had decreased feed and fright response, and mortality often reached 40%. Peak mortality occurred within 3 weeks of the appearance of clinical signs, and outbreaks typically lasted 6 weeks. Affected fish had no gross lesions but histologically had branchial epithelial necrosis and lamellar hyperplasia, with small to large numbers of scattered epithelial cells containing 10- to 20-µm inclusions. A longitudinal study was undertaken of one annual outbreak, and lamellar hyperplasia was most closely associated with mortality. The number of inclusions was statistically greater (P < 0.05) before and during peak mortality, but inclusions were present in low numbers before clinical signs occurred. Results of histochemical staining, immunohistochemistry and transmission electron microscopy supported the presence of a ß-proteobacteria rather than a Chlamydiales bacterium within inclusions. PCR primers to identify Chlamydiales did not give consistent results. However, the use of universal 16S rDNA bacterial primers in conjunction with laser capture microdissection of inclusions demonstrated that a ß-proteobacteria was consistently associated with affected gills and is more likely the cause of the disease in lake trout.

Single nucleotide polymorphisms in collagenous lectins and other innate immune genes in pigs with common infectious diseases.

Innate immune recognition of pathogens involves various surface receptors and soluble proteins that precede agglutination, complement activation, phagocytosis, and the adaptive immune response. Mannan-binding lectins (MBLs), ficolins (FCNs) and surfactant protein A (SP-A) are soluble collagenous lectins that bind surface structures of various bacteria, viruses and fungi. Some single nucleotide polymorphisms (SNPs) in collagenous lectin genes of humans and other species, including pigs, have been implicated in variation in susceptibility to infectious and inflammatory diseases. In this study we determined the frequencies of 13 SNP alleles of MBL-A, MBL-C, ficolin-α, ficolin-ß, and SP-A in 1324 healthy pigs and 461 pigs diagnosed with common infectious diseases at necropsy. For comparison, we also analyzed 12 other SNP alleles in several other innate immune genes, including galectins and TLRs. Several SNPs within genes encoding porcine MBL-A, MBL-C and SP-A were more frequent in pigs diagnosed at necropsy with various diseases or pathogens. These findings suggest that several collagenous lectin SNPs are associated with disease susceptibility and therefore might be genetic markers of impaired innate immune function.

Single nucleotide polymorphisms in mannan-binding lectins and ficolins in various strains of mice.

Mannan-binding lectin (MBL) and ficolin are collagenous lectins produced primarily by the liver and are involved in innate resistance to microbial pathogens. Mice have two MBL genes (Mbl1 and Mbl2) that encode MBL-A and MBL-C, respectively. Similarly, the murine Fcna and Fcnb genes encode ficolin-A and ficolin-B. Several single nucleotide polymorphisms (SNP) in the human MBL2 gene are responsible for various innate immune dysfunctions due to abnormal structure or expression of human MBL-C. In these studies, we identified SNPs in the expressed collagenous lectin genes Mbl1, Mbl2, Fcna, and Fcnb in 10 strains of mice designated high priority Group A strains by the Mouse Phenome Project (129S1/SvImJ, A/J, BALB/cByJ, C3H/HeJ, C57BL/6 J, DBA/2 J, FVB/NJ, SJL/J, CAST/EiJ and SPRET/EiJ) by sequencing gene exons by reverse transcription-polymerase chain reaction (RT-PCR). Sequence comparisons identified a total of 15 structural SNPs in Mbl1 in two strains, 27 SNPs in Mbl2 in five strains, and 19 and 15 SNPs in Fcna and Fcnb, respectively, in two strains. Two non-synonymous SNPs were identified in the collagen-like domain of mouse Fcnb that are similar to the coding polymorphisms in the collagen-like domain of human MBL2. Most of the non-synonymous SNPs identified in Mbl1 and Mbl2 occurred in the carbohydrate-recognition domains (CRDs), and some resulted in altered residues close to known ligand binding sites. Similarly, most non-synonymous SNPs of Fcna and Fcnb were identified in the fibrinogen-like CRD. The miscoding SNPs found in the CRD regions of mouse Mbl1, Mbl2, Fcna and Fcnb may be associated with strain differences in glycan binding avidity and disposition of microbial or host ligands. Furthermore, the non-synonymous mutations in the collagen-like domain of Fcnb may alter the structure of the mature ficolin-B protein leading to functional deficiencies. These differences may be important in the pathogenesis of susceptibility differences between inbred strains to various infectious microorganisms.