The impact of micro RNA gene polymorphisms on immune response to diphtheria vaccine in Iraqi children and adolescents

Abstract EN

Background: Since itsinvention in the first quarter ofthe last century, diphtheria toxoid was successfully used for vaccination against diphtheria.

However, sporadic case and even an epidemic have been recorded in many parts of the world, suggesting the presence of genetic factors influencing the immune response to this vaccine.

Aim: To assess the role of three single nucleotide polymorphisms(miRNA-146a G> C, miRNA- 49 T> G and miRNA-196a2 C> T) in miRNA genes in immune response to diph- theria vaccine.

Subjects and Methods: This study recruited 68 children and adolescents who received threedoses ofdiphtheria toxoid.

DNAwasisolated fromthebloodlymphocytes andmiRNA- 146a,miRNA-149 and miRNA-196a2 genes were amplified, and then directly sequenced.

Serum levels of anti-diphtheria toxoids IgG antibodies were determined by enzyme linked immunosorbent assay, and accordingly the immune response was categorized into good, moderate and low immunity .The association of different genotypes and alleles with immune statuswasillustrated statistically.

Results: Good immune response to diphtheria vaccine wassignificantly associated with the C allele of the polymorphism miRNA-146a G> C.

Out of 14 carriers of GG geno- type,11(78.57%)showed good immunity compared to only 48.15% of GG carriers who had such immunity (P=0.039).The mutant allele of miR-149 T> G was more prevalent than wild type allele G among subjects with good immunity.However,thedifferencewasinsignificant .Genotypes and allele frequencies of the SNP miR-196a2 C> T were very close in different immunologicalstatuses.

Conclusion: The results ofthe currentstudy suggest the significantrole of miRNA-146a G> C gene polymorphism and the insignificant role of both miRNA-149 T>G and miRNA- 196a2 C>T gene polymorphisms in response to diphtheria toxoids vaccine.

More studies are required to find out the associations of different polymorphisms in miRNA genes with immune response for differentvaccines.-