Major Histocompatibility Complex IIB Research Articles

Disentangling the role of MHC‐dependent ‘good genes' and ‘compatible genes' in mate‐choice decisions of three‐spined sticklebacks Gasterosteus aculeatus under semi‐natural conditions

To investigate and disentangle the role of major histocompatibility complex (MHC)-based 'good genes' and 'compatible genes' in mate choice, three-spined sticklebacks Gasterosteus aculeatus with specific MHC IIB genotypes were allowed to reproduce in an outdoor enclosure system. Here, fish were protected from predators but encountered their natural parasites. Mate choice for an intermediate genetic distance between parental MHC genotypes was observed, which would result in intermediate diversity in the offspring, but no mate choice based on good genes was found under the current semi-natural conditions. Investigation of immunological variables revealed that the less-specific innate immune system was more active in individuals with a genetically more divergent MHC allele repertoire. This suggests the need to compensate for an MHC-diminished T-cell repertoire and potentially explains the observed mate choice for intermediate MHC genetic distance. The present findings support a general pattern of mate choice for intermediate MHC diversity (i.e. compatible genes). In addition, the potentially dynamic role of MHC good genes in mate choice under different parasite pressures is discussed in the light of present and previous results.

Molecular cloning, genomic structure, polymorphism and expression analysis of major histocompatibility complex class IIA and IIB genes of half-smooth tongue sole ( Cynoglossus semilaevis)

Major histocompatibility complex (MHC) genes play an important role in the immune response of vertebrates. Its function is to present foreign peptide to the T-cell. In order to study the function and molecular polymorphism of class II genes in teleost, the full lengths of MHC class IIA and IIB cDNA were cloned from half-smooth tongue sole by homology cloning and rapid amplification of cDNA ends polymerase chain reaction (RACE-PCR). Genomic organizations, molecular polymorphism, and expression profiles of class IIA and IIB were examined to study the function in fish. As in other teleost, four exons and three introns were identified in half-smooth tongue sole class IIA gene, five exons and four introns were identified in class IIB gene. The deduced amino acid sequence of class IIA had 27.3–69.8% identity with those of mammal and teleost. Nine class IIA alleles were identified from four individuals. Four different alleles observed in a single individual may infer the existence of two loci at least. The deduced amino acid sequence of class IIB had 7.9–71.9% identity with those of other species. Fifteen class IIB alleles were identified. Six different alleles observed in a single individual may suggest that there are at least three loci in class IIB genes. Real-time quantitative RT-PCR demonstrated that the MHC class IIA and IIB were ubiquitously expressed in twelve normal tissues. Challenge of half-smooth tongue sole with the pathogenic bacteria, Vibrio anguillarum, resulted in significant changes in the expression of MHC IIA and IIB mRNA in three tissues.

MHC polymorphism and disease resistance to Vibrio anguillarum in 12 selective Japanese flounder ( Paralichthys olivaceus) families

Genetic variation in the major histocompatibility complex (MHC) class IIB was tested in Japanese flounder ( Paralichthys olivaceus) for survival after challenge with bacterial infection. The material consisted of 6000 Japanese flounder from 60 families challenged with Vibrio anguillarum, which causes significantly different mortality in flounder families. Five individuals from each of six high-resistance (HR) and six low-resistance (LR) families were screened for their MHC class IIB genotypes using sequence analysis. High polymorphism of MHC IIB gene and at least three loci were discovered in Japanese flounder and the rate of d N occurred at a significantly higher frequency than that of d S in PBR. Among 60 individuals, 76 alleles were discovered and 15 alleles were used to study associations between alleles and resistance to disease. We found highly significant associations between resistance towards infectious disease caused by V. anguillarum and MHC class IIB polymorphism in Japanese flounder. Some alleles appeared in both HR and LR families, while some alleles were only discovered in HR or LR families. One allele, Paol-DAB*4301, was significantly more prevalent in HR families than in LR families ( P = 0.023). Paol-DAB*0601, Paol-DAB*0801, Paol-DAB*2001, Paol-DAB*3803 were discovered in two HR families with high frequency. One allele, Paol-DAB*1601, was discovered in three LR families. The steady heredity of MHC class IIB alleles was observed, and the family having Paol-DAB*4301 alleles was confirmed with higher resistance to V. anguillarum. This study confirmed the association between alleles of MHC class IIB gene and disease resistance, and also detected some alleles which might be correlated with high bacterial infection resistance. The disease resistance-related MHC markers could be used for molecular marker-assisted selective breeding in the flounder.

Major Histocompatibility Complex Class IIB Allele Polymorphism and Its Association with Resistance/Susceptibility to Vibrio anguillarum in Japanese Flounder (Paralichthys olivaceus)

The full length of major histocompatibility complex (MHC) class IIB cDNA was cloned from a Chinese population of Paralichthys olivaceus by homology cloning and rapid amplification of cDNA ends-polymerase chain reaction (RACE-PCR). The MHC IIB genomic sequence is 1,864 bp long and consists of 34-bp 5'UTR, 741-bp open reading frame, 407-bp 3'UTR, 96-bp intron1, 392-bp intron2, 85-bp intron3, and 109-bp intron4. Phylogenetic analysis showed that the putative MHC class IIB amino acid of the Chinese P. olivaceus shared 28.3% to 85.4% identity with that of the reported MHC class IIB in other species. A significant association between MHC IIB polymorphism and disease resistance/susceptibility was found in Chinese P. olivaceus. Thirteen different MHC IIB alleles were identified among 411 clones from 84 individuals. Among the 280 (268) nucleotides, 32 (11.4%) nucleotide positions were variable. Most alleles such as alleles a, b, c, d, e, f, j, k, i, m were commonly found in both resistant and susceptible stock. Via chi2 test, allele d was significantly more prevalent in individuals from susceptible stock than from resistant stock, and their percentages were 23.80% and 7.14%, respectively. In addition, allele g occurred in 9 and allele h in 4 of 42 resistant individuals that were not present in the susceptible stock; their percentages were 21.4% and 9.52%, respectively. Although allele l was found only in 8 individuals from the susceptible stock, its percentage is 19.05%.

Cloning, characterization and expression of cDNA containing major histocompatibility complex class I, IIalpha and IIbeta genes of Japanese flounder Paralichthys olivaceus

: The nucleotide sequences of Japanese flounder Paralichthys olivaceus, major histocompatibility complex (MHC) cDNA, classical MHC class Iα, non-classical MHC class Iβ, MHC class IIα and IIβ, were determined. The domain structures and antigen binding motifs of vertebrate MHC are conserved in the Japanese flounder MHC. A phylogenetic analysis supports the classification of these genes into class I and class II MHC. Classical MHC class Iα was ubiquitously expressed, whereas the non-classical MHC class Iβ was expressed mainly in lymphoid organs, gills, intestine and stomach. The MHC classes IIα and IIβ were also ubiquitously expressed.