Molecular cloning and sequencing of porcine C5 gene and its association with immunological traits

The Relationship between Complement Components C1R and C5 Gene Polymorphism and the Values of Blood Indices in Suckling Piglets

The main mechanism of innate immunity is the complement system. Its components include the protein products of the C1R and C5 genes, which are involved in the classical activation pathway as well as the inflammatory and cytolytic immune responses, respectively. The aim of this study was to determine the relationship between PCR-restriction fragment length polymorphism in C1R (726T > C) and C5 (1044A > C) genes, and the values of hematological and biochemical blood indices in suckling crossbred (Polish Large White × Polish Landrace × Duroc × Pietrain) piglets (n = 473), considering their age (younger, 21 ± 3 days, n = 274; older, 35 ± 3 days, n = 199) and health status. The frequencies of the C5 genotypes deviated from the Hardy-Weinberg expectations. Younger piglets, healthy piglets, piglets that deviated from physiological norms and older piglets with the C1R TT genotype all had lower white and red blood cell indices. In piglets with the C5 CC genotype, younger piglets, piglets that deviated from physiological norms and older piglets, a greater number and/or percentage of monocytes were recorded in the blood. Older piglets also showed an increase in the number of leukocytes and granulocytes, along with a tendency for a decrease in the percentage of lymphocytes in their blood. We concluded that a polymorphism in the C1R gene may exhibit a functional association or genetic linkage with other genes involved in the process of erythropoiesis. Furthermore the relationship between the C5 gene polymorphism and the number and/or percentage of monocytes in the blood may modify the body's defense abilities. Piglets with the CC genotype, having an increased number/proportion of these cells in their blood, probably display a weakened immune response to pathogens or a chronic stimulation of the immune system.

Molecular Identification and Sequencing of <I>Mycoplasma gallisepticum</I> Recovered from Broilers in Egypt

BACKGROUND AND OBJECTIVES

Avian mycoplasmosis, particularly Mycoplasma gallisepticum (MG) is one of the infectious diseases associated with economic losses in Egyptian poultry industry. Thus, this study was aimed to determine the prevalence, serological identification, molecular characterization, sequencing and minimum inhibitory concentration of M. gallisepticum isolated from diseased broilers in Egypt.

MATERIALS AND METHODS

A total of 351 samples (227 tissue samples "tracheas and air sacs" and 124 tracheal swabs) and 71 sera were collected from diseased broilers. The conventional (isolation and biochemical) and molecular methods (PCR) were performed for detection of M. gallisepticum and virulence-associated gene (mgc2). The serum plate agglutination (SPA) test and enzyme-linked immunosorbent assay (ELISA) were applied on sera for determination of the presence of antibodies against M. gallisepticum. The minimal inhibitory concentration test (MIC) was used to determine the sensitivity of two sequenced M. gallisepticum strains to anti-mycoplasma agents.

RESULTS

The total recovery rate of Mycoplasma from 351 samples from broilers was 45.29% (159) in which M. gallisepticum showed a prevalence of 62.89% (100/159). Serological identification of M. gallisepticum in 71 collected sera using SPA and ELISA were 54.9 and 40.8% with the highest geometric mean titer of ELISA for M. gallisepticum (699.08 and 495.92). Molecular characterization of Mycoplasma using PCR showed that 50% (3/6) of tested isolates were identified as M. gallisepticum based on 16SrRNA. Also, the mgc2 gene was detected in 50% (3/6) M. gallisepticum isolates. Two positive PCR mgc2 specific genes of M. gallisepticum isolates were subjected to gene target sequencing (GTS) to verify that these two isolates were M. gallisepticum. The minimal inhibitory concentration test (MIC) was applied to determine the sensitivity of these two sequenced M. gallisepticum strains to anti-mycoplasma agents. The first M. gallisepticum isolate was sensitive to tilmicosin, tiamulin and spiramycin. The second M. gallisepticum isolate showed sensitivity to tiamulin, spiramycin and tilmicosin.

CONCLUSION

These results summarized the necessity of monitoring the Egyptian poultry farms for avian mycoplasmosis. Also, further studies are required for controlling of mycoplasma in all stages of the poultry industry production chain to avoid different losses in Egypt.

Effect of complement component 5 polymorphisms on mastitis resistance in Egyptian buffalo and cattle

Mastitis is one of the costliest diseases affecting the world's dairy industry. The important contribution of complement Component 5 (C5) to phagocytosis, which plays a major role in the defence of the bovine mammary gland against infection, makes this component of innate immunity a potential contributor in defending udder against mastitis. The objectives of this study were to sequence and analyse the whole coding region of the C5 gene in Egyptian buffalo and cattle, to detect any nucleotide variations (polymorphisms) and to investigate their associations with milk somatic cell score (SCS) as an indicator of mastitis in dairy animals. We sequenced a buffalo C5 cDNA fragment of 5336 bp (KP221293) and a cattle C5 cDNA fragment of 5303 bp (KP221294), which included the whole coding region and 3-UTR. Buffalo and cattle C5 cDNA shared sequence identity of 99%. The predicted complement C5 proteins consist of 1677 amino acid residues in both animals, one amino acid less than in humans and three amino acids more than in mouse C5 protein. Comparing cDNA sequences of different animals revealed nine novel SNPs in buffalo and seven SNPs in cattle, with two of them being novel. The association analysis revealed that five SNPs in buffalo are highly associated with SCS; indicating the contribution of complement C5 variants in buffalo mastitis resistance. No significant associations were detected between C5 variants and SCS in cattle. This is the first report about C5 variants in buffalo and its association with SCS.

Genetic Association of the Porcine C9 Complement Component with Hemolytic Complement Activity

The complement system is a part of the natural immune regulation mechanism against invading pathogens. Complement activation from three different pathways (classical, lectin, and alternative) leads to the formation of C5-convertase, an enzyme for cleavage of C5 into C5a and C5b, followed by C6, C7, C8, and C9 in membrane attack complex. The C9 is the last complement component of the terminal lytic pathway, which plays an important role in lysis of the target cells depending on its self-polymerization to form transmembrane channels. To address the association of C9 with traits related to disease resistance, the complete porcine C9 cDNA was comparatively sequenced to detect single nucleotide polymorphisms (SNPs) in pigs of the breeds Hampshire (HS), Duroc (DU), Berlin miniature pig (BMP), German Landrace (LR), Pietrain (PIE), and Muong Khuong (Vietnamese potbelly pig). Genotyping was performed in 417 F2 animals of a resource population (DUMI: DU×BMP) that were vaccinated with Mycoplasma hyopneumoniae, Aujeszky diseases virus and porcine respiratory and reproductive syndrome virus at 6, 14 and 16 weeks of age, respectively. Two SNPs were detected within the third exon. One of them has an amino acid substitution. The European porcine breeds (LR and PIE) show higher allele frequency of these SNPs than Vietnamese porcine breed (MK). Association of the substitution SNP with hemolytic complement activity indicated statistically significant differences between genotypes in the classical pathway but not in the alternative pathway. The interactions between eight time points of measurement of complement activity before and after vaccinations and genotypes were significantly different. The difference in hemolytic complement activity in the both pathways depends on genotype, kind of vaccine, age and the interaction to the other complement components. These results promote the porcine C9 (pC9) as a candidate gene to improve general animal health in the future.

The porcine innate immune system: an update

Over the last few years, we have seen an increasing interest and demand for pigs in biomedical research. Domestic pigs (Sus scrofa domesticus) are closely related to humans in terms of their anatomy, genetics, and physiology, and often are the model of choice for the assessment of novel vaccines and therapeutics in a preclinical stage. However, the pig as a model has much more to offer, and can serve as a model for many biomedical applications including aging research, medical imaging, and pharmaceutical studies to name a few. In this review, we will provide an overview of the innate immune system in pigs, describe its anatomical and physiological key features, and discuss the key players involved. In particular, we compare the porcine innate immune system to that of humans, and emphasize on the importance of the pig as model for human disease.

Identification, cloning and characterization of an extracellular signal-regulated kinase (ERK) from Chinese shrimp, Fenneropenaeus chinensis

Extracellular signal-regulated kinase (ERK) is a serine/threonine-specific protein kinase, which participates in signaling transduction pathways that control intracellular events, including resumption of meiosis, embryogenesis, cell differentiation, cell proliferation, cell death and response to radiation. Some virus species evolved the ability to hijack the host cell ERK signaling transduction pathway for viral replications and gene expressions. To obtain a better understanding of ERK, we cloned a cDNA encoding ERK from the muscle of Fenneropenaeus chinensis (FcERK). The FcERK contained a 1098 bp open reading frame (ORF) encoding a protein of 365 amino acid residues with a conserved phosphorylation motif TEY in the kinase activation loop. Pair-wise and multiple sequence alignment revealed that ERK is highly conserved across taxa. The FcERK gene expressions in the hepatopancreas and gill were noticeably higher than the expression observed in the muscle. A challenge test was performed to reveal the responses of FcERK in different tissues to white spot syndrome virus (WSSV) infection. Post WSSV challenge, the FcERK expression in the gill significantly increased during the early stage of the viral infection, the FcERK expression in the muscle increased later than that in the gill, and the FcERK expression in the hepatopancreas significantly decreased. The FcERK gene expression profile accorded with the results that the virus primarily infects tissues originating from the ectoderm, with less infection of the tissues originating from the mesoderm, and hardly any infection in the tissues originating from the entoderm. Two single nucleotide polymorphisms (SNPs) were identified in the FcERK gene, involving C/T transition. The SNP genotypes of two groups of shrimps, respectively comprising 96 WSSV-resistant shrimps and 96 WSSV-susceptible shrimps were obtained using a high-resolution melting (HRM) method. In the two groups, the MAFs of both sites were greater than 0.05, and no site departed significantly (P < 0.05) from HWE. The genotype distributions of both mutation sites between the two groups were not significantly different. These results lead to a better understanding of the molecular mechanisms of the host-virus interaction and provide useful information for disease control.

The three-way relationship of polymorphisms of porcine genes encoding terminal complement components, their differential expression, and health-related phenotypes

Background

The complement system is an evolutionary ancient mechanism that plays an essential role in innate immunity and contributes to the acquired immune response. Three modes of activation, known as classical, alternative and lectin pathway, lead to the initiation of a common terminal lytic pathway. The terminal complement components (TCCs: C6, C7, C8A, C8B, and C9) are encoded by the genes C6, C7, C8A, C8B, C8G, and C9. We aimed at experimentally testing the porcine genes encoding TCCs as candidate genes for immune competence and disease resistance by addressing the three-way relationship of genotype, health related phenotype, and mRNA expression.

Results

Comparative sequencing of cDNAs of animals of the breeds German Landrace, Piétrain, Hampshire, Duroc, Vietnamese Potbelly Pig, and Berlin Miniature Pig (BMP) revealed 30 SNPs (21 in protein domains, 12 with AA exchange). The promoter regions (each ~1.5 kb upstream the transcription start sites) of C6, C7, C8A, C8G, and C9 exhibited 29 SNPs. Significant effects of the TCC encoding genes on hemolytic complement activity were shown in a cross of Duroc and BMP after vaccination against Mycoplasma hyopneumoniae, Aujeszky disease virus and PRRSV by analysis of variance using repeated measures mixed models. Family based association tests (FBAT) confirmed the associations. The promoter SNPs were associated with the relative abundance of TCC transcripts obtained by real time RT-PCR of 311 liver samples of commercial slaughter pigs. Complement gene expression showed significant relationship with the prevalence of acute and chronic lung lesions.

Conclusions

The analyses point to considerable variation of the porcine TCC genes and promote the genes as candidate genes for disease resistance.

Molecular and expression analysis of complement component C5 in the nurse shark (Ginglymostoma cirratum) and its predicted functional role

We present the complete cDNA sequence of shark (Ginglymostoma cirratum) pro-C5 and its molecular characterization with a descriptive analysis of the structural elements necessary for its potential functional role as a potent mediator of inflammation (fragment C5a) and initiator molecule (fragment C5b) for the assembly of the membrane attack complex (MAC) upon activation by C5 convertase. In mammals the three complement activation cascades, the classical, alternative and lectin pathways, converge at the activation of C3, a pivotal complement protein. It is, however, the subsequent activation of the next complement component, C5, which is the focal point at which the initiation of the terminal lytic pathway takes place and involves the stepwise assembly of the MAC. The effector cytolytic function of complement occurs with the insertion of MAC into target membranes causing dough-nut like holes and cell leakage. The lytic activity of shark complement results in structurally similar holes in target membranes suggesting the assembly of a shark MAC that likely involves a functional analogue of C5. The composition of shark MAC remains unresolved and to date conclusive evidence has been lacking for shark C5. The gene has not been cloned nor has the serum protein been characterized for any elasmobranch species. This report is the first to confirm the presence of C5 homologue in the shark. GcC5 is remarkably similar to human C5 in overall structure and domain arrangement. The GcC5 cDNA measured 5160-bp with 5' and 3' UTRs of 35 bp and 79 bp, respectively. Structural analysis of the derived protein sequence predicts a molecule that is a two-chain structure which lacks a thiolester bond and contains a C5 convertase cleavage site indicating that activation will generate two peptides, akin to C5b and C5a. The putative GcC5 molecule also contains the C-terminal C345C/Netrin module that characterizes C3, C4 and C5. Multiple alignment of deduced amino acid sequences shows that GcC5 shares more amino acid identities/similarities with mammals than that with bony fish. We conclude that at the time of emergence of sharks the elaborate mosaic structure of C5 had already evolved.

Quantitative trait loci for white blood cell numbers in swine

Differential white blood cell counts are essential diagnostic parameters in veterinary practice but knowledge on the genetic architecture controlling variability of leucocyte numbers and relationships is sparse, especially in swine. Total leucocyte numbers (Leu) and the differential leucocyte counts, i.e. the fractions of lymphocytes (Lym), polymorphonuclear leucocytes [neutrophils (Neu), eosinophils (Eos) and basophils (Bas)] and monocytes (Mon) were measured in 139 F(2) pigs from a Meishan/Pietrain family, before and after challenge with the protozoan pathogen Sarcocystis miescheriana for genome-wide quantitative trait loci (QTL) analysis. After infection, the pigs passed through three stages representing acute disease, reconvalescence and chronic disease. Nine genome-wide significant and 29 putative, single QTL controlling leucocyte traits were identified on 15 chromosomes. Because leucocyte traits varied with health and disease status, QTL influencing the leucocyte phenotypes showed specific health/disease patterns. Regions on SSC1, 8 and 12 contained QTL for baseline leucocyte traits. Other QTL regions reached control on leucocyte traits only at distinct stages of the disease model. Two-thirds of the QTL have not been described before. Single QTL explained up to 19% of the phenotypic variance in the F(2) animals. Related traits were partly under common genetic influence. Our analysis confirms that leucocyte trait variation is associated with multiple chromosomal regions.

Confirmation of QTL on porcine chromosomes 1 and 8 influencing leukocyte numbers, haematological parameters and leukocyte function

A genome wide search in European Wild Boar x Swedish Yorkshire (W x Y) inter-cross pigs has earlier identified quantitative trait loci (QTL) for leucocyte number and function on porcine chromosomes 1 and 8 (SSC 1 and 8). To verify the involvement of these chromosomal regions in the regulation of haematocrit (Hem) and haemoglobin (Hb) levels, leucocyte numbers and in vitro leukocyte functions (mitogen induced proliferation and IL-2 production, virus induced interferon-alpha production and neutrophil phagocytosis), animals of different genetic backgrounds were analysed. The animals comprised a back-cross sire family (n=47) of W x Y pigs and six crossbred [Y x Landrace (L)] sire families (n=191). They were genotyped for 16 genetic markers and an interval analysis was performed. On SSC1, a QTL close to S0082 on the q-arm that influenced numbers of white blood cells in L x Y pigs and numbers of band neutrophils and CD8(+) cells in W x Y pigs was identified (P<or=0.01). An additional SSC1 QTL was identified on the p-arm close to S0008 with influence on numbers of CD2(+) cells in W x Y pigs (P<or=0.05). On SSC8, a QTL influencing Hb (P<or=0.01) and Hem (P<or=0.05) levels was identified close to KIT in the W x Y pigs. For L x Y pigs, a second QTL, distal to KIT and close to S0069, on SSC8 influenced the numbers of MHCII(+) cells and mitogen induced proliferation (P<or=0.05), whilst the QTL close to KIT influenced the number of IgM(+) cells in these pigs (P<or=0.05). The results confirm the involvement of earlier identified regions of SSC1 and SSC8 on porcine immune parameters and some candidate genes were suggested.