Association between polymorphisms in OAS2 and CD209 genes and predisposition to chronic hepatitis C in Russian population

Genetic Ethnic Differences in Human 2'-5'-Oligoadenylate Synthetase and Disease Associations: A Systematic Review

Recently, several studies have highlighted a skewed prevalence of infectious diseases within the African continent. Furthermore, a growing number of studies have demonstrated unique genetic variants found within the African genome are one of the contributing factors to the disease severity of infectious diseases within Africa. Understanding the host genetic mechanisms that offer protection against infectious diseases provides an opportunity to develop unique therapeutic interventions. Over the past two decades, several studies have linked the 2'-5'-oligoadenylate synthetase (OAS) family with a range of infectious diseases. More recently, the OAS-1 gene has also been associated with disease severity caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which led to a global pandemic. The OAS family serves as an antiviral factor through the interaction with Ribonuclease-Latent (RNase-L). This review explores the genetic variants observed within the OAS genes and the associations with various viral infections and how previously reported ethnic-specific polymorphisms drive clinical significance. This review provides an overview of OAS genetic association studies with a particular focus on viral diseases affecting individuals of African descent.

Identification, expression patterns, evolutionary characteristics and recombinant protein activities analysis of CD209 gene from Megalobrama amblycephala

CD209 is a type II transmembrane protein in the C-type lectin family, which is involved in the regulation of innate and adaptive immune system. Although it has been widely studied in mammals, but little has been reported about fish CD209 genes. In the present study, Megalobrama amblycephala CD209 (MaCD209) gene was cloned and characterized, its expression patterns, evolutionary characteristics, agglutinative and bacteriostatic activities were analyzed. These results showed that the open reading frame (ORF) of MaCD209 gene was 795 bp, encoding 264 aa, and the calculated molecular weight of the encoded protein was 29.7 kDa. MaCD209 was predicted to contain 2 N-glycosylation sites, 1 functional domain (C-LECT-DC-SIGN-like) and 1 transmembrane domain. Multiple sequence alignment showed that the amino acid sequence of MaCD209 was highly homologous with that of partial fishes, especially the highly conserved C-LECT-DC-SIGN-like domain and functional sites of CD209. Phylogenetic analysis showed that the CD209 genes from M. amblycephala and other cypriniformes fishes were clustered into one group, which was reliable and could be used for evolutionary analysis. Then, adaptive evolutionary analysis of teleost CD209 was conducted, and several positively selected sites were identified using site and branch-site models. Quantitative real-time PCR analysis showed that MaCD209 gene was highly expressed in the liver and heart. Moreover, the expression of MaCD209 was significantly induced upon Aeromonas hydrophila infection, with the peak levels at 4 h or 12 h post infection. The immunohistochemical analysis also revealed increased distribution of MaCD209 protein post bacterial infection. In addition, recombinant MaCD209 (rMaCD209) protein was prepared using a pET32a expression system, which showed excellent bacterial binding and agglutinative activities in a Ca²⁺-independent manner. However, rMaCD209 could only inhibit the proliferation of Escherichia coli rather than A. hydrophila. In conclusion, this study identified the MaCD209 gene, detected its expression and evolutionary characteristics, and evaluated the biological activities of rMaCD209 protein, which would provide a theoretical basis for understanding the evolution and functions of fish CD209 genes.

Association of CD209 (DC-SIGN) rs735240 SNV with paucibacillary leprosy in the Brazilian population and its functional effects

BACKGROUND

Leprosy, caused by Mycobacterium leprae, is a public health problem in Brazil that affects peripheral nerves, resulting in physical disabilities. During host-pathogen interactions, the immune response determines leprosy outcomes from a localised (paucibacillary) form to a disseminated (multibacillary) form. The recognition of M. leprae involves the DC-SIGN receptor, which is present on the dendritic cells (DCs) and participates in immune activation.

OBJECTIVES

To evaluate the association of polymorphisms in the promoter region of the gene encoding DC-SIGN (CD209) and the clinical form of leprosy, and to investigate its functional effects.

METHODS

The study population included 406 leprosy patients from an endemic area in Brazil [310 multibacillary (MB); 96 paucibacillary (PB)]. A functional evaluation based on the effects of the single nucleotide variant (SNV) associated with PB leprosy on the specific immune response was also performed.

RESULTS

The GA genotype and the presence of the A allele of rs735240 (-939G>A) were associated with PB leprosy [OR: 2.09 (1.18-3.69) and 1.84 (1.07-3.14), respectively]. Carriers of the A allele showed reduced expression of CD209 and TGF-β1 in leprosy lesions in comparison with individuals with GG genotype, in addition to a higher response to the Mitsuda test.

CONCLUSION

These data suggest that rs735240 influences the immune response against M. leprae and clinical presentation of leprosy.

Upregulation of the type I interferon pathway in feedlot cattle persistently infected with bovine viral diarrhea virus

Bovine viral diarrhea virus (BVDV) has a profound economic impact on the cattle industry. Calves infected in utero and born persistently infected (PI) with BVDV have increased morbidity, mortality, and reduced productivity. Further, they serve as a continual source of viral exposure to herd mates and thereby pose a significant risk to animal wellbeing and production efficiency. Understanding the mechanisms through which PI is established and maintained is therefore important in working toward finding means to prevent or mitigate losses due to infection. Early studies of acute infection suggested BVDV infection alters the host's ability to mount a type I interferon (IFN) response, thereby allowing for the establishment of PI. More recently, however, animals experimentally challenged with the virus demonstrated a chronic yet modest upregulation of the IFN pathway. To identify if the IFN or other pathways are altered due to PI by BVDV in a natural infection, the circulating blood transcriptome was analyzed from PI feedlot cattle (N = 10 BVDV1a, 8 BVDV1b, 8 BVDV2), cattle co-mingling with PI cattle but not themselves infected (N = 9), and a group of unrelated, unexposed controls (N=10). Differential expression analyses included contrasts among BVDV subtypes, and all pair-wise comparisons of PI, co-mingled non-PI, and unexposed animals. Analyses in limma-voom revealed no difference in the transcriptome based upon the BVDV genotype with which the animal was infected. However, gene expression did differ (adj P < 0.05 and |logFC|> 1) at 175 loci between the PI and co-housed, non-PI contemporaries and when compared to the unexposed controls, 489 loci were differentially expressed. Pathway analyses predict that alterations in the transcriptome of the PI cattle indicate significant upregulation of innate immune function including IFN signaling. These data support prior work suggesting IFN signaling is not completely suppressed in cattle naturally PI with BVDV.

Impact of double-stranded RNA characteristics on the activation of human 2'-5'-oligoadenylate synthetase 2 (OAS2)

Human 2'-5' oligoadenylate synthetases (OAS) are a family of interferon-inducible proteins that, upon activation by double-stranded RNA, polymerize ATP into 2'-5' linked oligoadenylates. In this study, we probed the RNA cofactor specificity of the two smallest isozymes, OAS1 and OAS2. First, we developed a strategy for the expression and purification of recombinant human OAS2 from eukaryotic cells and quantified the activity of the enzyme relative to OAS1 in vitro. We then confirmed that both OAS2 domains, as opposed to only the domain containing the canonical catalytic aspartic acid triad, are required for enzymatic activity. Enzyme kinetics of both OAS1 and OAS2 in the presence of a variety of RNA binding partners enabled characterization of the maximum reaction velocity and apparent RNA-protein affinity of activating RNAs. While in this study OAS1 can be catalytically activated by dsRNA of any length greater than 19 bp, OAS2 showed a marked increase in activity with increasing dsRNA length with a minimum requirement of 35 bp. Interestingly, activation of OAS2 was also more efficient when the dsRNA contained 3'-overhangs, despite no significant impact on binding affinity. Highly structured viral RNAs that are established OAS1 activators were not able to activate OAS2 enzymatic activity based on the lack of extended stretches of dsRNA of greater than 35 bp. Together these results may highlight distinct subsets of biological RNAs to which different human OAS isozymes respond.

Single nucleotide polymorphism rs1800872 in the promoter region of the IL10 gene is associated with predisposition to chronic hepatitis C in Russian population

Previously, we studied an association of two IL28B gene single nucleotide polymorphisms (SNPs) and three IL10 gene SNPs with predisposition to tick-borne encephalitis in a Russian population. In this study, a possible involvement of these SNPs in the development of predisposition to chronic hepatitis C (caused by structurally similar, related virus from the Flaviviridae family) was investigated in the same population. Only the IL10 promoter rs1800872 SNP was associated with predisposition to chronic hepatitis C. This SNP seems to be a common genetic marker of predisposition to two diseases caused by hepatitis C and tick-borne encephalitis viruses in Russian population.

Mx1, OAS1 and OAS2 polymorphisms are associated with the severity of liver disease in HIV/HCV-coinfected patients: A cross-sectional study

The mechanisms involved in the chronic hepatitis C progression are incompletely understood. The aim was to analyze the association between 2'5'oligoadenylate synthetase 1,2 and 3 (OAS1-3) and myxovirus resistance proteins 1 (Mx1) polymorphisms and severity of liver disease in human immunodeficiency virus (HIV)/hepatitis C virus (HCV) coinfected patients. We performed a cross-sectional study in 219 patients that underwent a liver biopsy. DNA genotyping for Mx1 (rs469390), OAS1 (rs2285934), OAS2 (rs1293762) and OAS3 (rs2010604) was performed by using GoldenGate assay. The outcome variables ion liver biopsy were: (i) significant fibrosis (F ≥ 2); (ii) moderate activity grade (A ≥ 2). Additive model of inheritance for genetic association test was used. The likelihood of having significant fibrosis (F ≥ 2) was lower in patients carrying OAS2 rs1293762 A allele [adjusted odds ratio (aOR) = 0.51; p = 0.040]. Besides, the likelihood of having moderate activity grade (A ≥ 2) was higher in patients carrying Mx1 rs464397 C allele (aOR = 1.63; p = 0.028) and Mx1 rs469390 G allele (aOR = 1.97; p = 0.005), while it was lower in patients carrying OAS1 rs2285934 A allele (aOR = 0.64; p = 0.039) and OAS2 rs1293762 A allele (aOR = 0.41; p = 0.009). In conclusion, Mx1 and OAS1-2 polymorphisms were associated with the severity of liver disease in HIV/HCV-coinfected patients, suggesting a significant role in the progression of hepatic fibrosis.

CD209 promoter polymorphisms associate with HCV infection and pegylated-interferon plus ribavirin treatment response

Hepatitis C is a severe liver disease caused by hepatitis C virus that could persist in the host causing progression towards chronic disease in about 80% of the cases. Pegylated-interferon plus ribavirin was the gold standard therapy, however treatment's response was quite variable among individuals and different host/viral factors may play a role in disease outcome. The cluster of differentiation 209 (CD209 antigen) is a component of the innate immune system able to recognize HCV and consequently activating the immune response. We enrolled 203 Italian HCV infected patients and 220 healthy controls investigating if five promoter polymorphisms within CD209 gene (encoding for CD209 antigen) correlated with HCV infection susceptibility, spontaneous viral clearance and interferon treatment response. CD209 -939G>A and -871A>G polymorphisms associated with HCV infection susceptibility, while, CD209 -871A>G and -336A>G polymorphisms associated with response to treatment. In conclusion, CD209 polymorphisms could play a role in the susceptibility to HCV infection as well as interferon treatment response in our study population from North-East of Italy.