Abstract
During the 2015-2016 epidemic, Brazil was the country with the highest rate of Zika virus (ZIKV) infection in the Americas. Twenty-nine percent of pregnant women positive for ZIKV exhibited ultrasound scans with fetus anomalies. Human leukocyte antigen-G (HLA-G) exerts immunoregulatory effects by binding to inhibitory receptors, namely LILRB1 and LILRB2, thus preventing mother-fetus rejection and vertical pathogen transmission. The binding of HLA-G to one of its receptors modulates both innate and adaptive immunity. However, in a viral infection, these molecules may behave as pathogenic mediators shifting the pregnancy environment from an anti-inflammatory profile to a pro-inflammatory phenotype. Genetic mutations might be associated with the change in phenotype. This study aimed to explore the possible role of polymorphic sites in HLA-G, LILRB1 and LILRB2 in mother-fetus ZIKV transmission. Polymorphisms were detected by direct sequencing. Differences in allele and/or genotype frequencies for each SNP analyzed among ZIKV non-transmitting and transmitting mother-child pairs, among ZIKV-transmitting and non-transmitting mothers and between ZIKV-infected and non-infected children were compared by Mid-P exact test or Yates' correction. Significant susceptibility of ZIKV vertical transmission is suggested in ZIKV-transmitting and non-transmitting mothers and ZIKV-infected and non-infected children for LILRB1_rs1061684 T/T (p = 0.03, Pc = 0.06, OR = 12.4; p = 0.008, Pc = 0.016, OR = 16.4) and LILRB1_rs16985478 A/A (p = 0.01, Pc = 0.02, OR = 19.2; p = 0.008, Pc = 0.016, OR = 16.4). HLA-G_rs1710 (p = 0.04, Pc = 0.52, OR = 4.30) was also a susceptibility factor. LILRB2_rs386056 G/A (p = 0.02, Pc = 0.08, OR = 0.07), LILRB2_rs7247451 G/G (p = 0.01, Pc = 0.04, OR = 0.04) and HLAG_rs9380142 T/T (p = 0.04, Pc = 0.52, OR = 0.14) were suggested as protective factors against vertical transmission. The current study suggests that polymorphic sites in the LILRB1 and HLA-G genes might be associated with mother-to-child ZIKV transmission while LILRB2 might be associated with protection against ZIKV transmission in the womb in a population from the south and southeast of Brazil.