Lack of association of the KIR and HLA class I ligands with ZIKV infection in south and southeast of Brazil

BACKGROUND Zika virus (ZIKV) is an emerging arbovirus associated with foetal malformations and neurological complications. The infection is usually associated with mild symptoms. The comparison between the allelic frequency of polymorphic genes in symptomatic infected individuals in the population can clarify the pathogenic mechanisms of ZIKV. During ZIKV infection, cytokines are produced and natural killer (NK) cells are recruited, whose activation depends on signaling pathways activated by specific receptors, such as killer cell immunoglobulin-like receptors (KIR). These molecules interact with human leukocyte antigen (HLA) class I ligands and are encoded by polymorphic genes. OBJECTIVES This study aimed to evaluate the frequency of allelic variants of the genes encoding the KIR receptors and their HLA class I ligands in 139 symptomatic ZIKV-patients and 170 controls negative for the virus, and to evaluate the role of these variants for ZIKV susceptibility. METHODS KIR and HLA class I genes were genotyped using the polymerase chain reaction-sequence specific oligonucleotide (PCR-SSO) technique. FINDINGS No significant differences in the frequency distribution of KIRs and KIR-HLA in patients compared to controls were observed. MAIN CONCLUSIONS KIR and its HLA ligands might play a minor role in ZIKV infection in the south and southeast Brazilian individuals.

Investigation of the A1555G mutation in mitochondrial DNA (MT-RNR1) in groups of Brazilian individuals with nonsyndromic deafness and normal-hearing.

BACKGROUND: Mutations of mitochondrial DNA were described into two genes: The mitochondrially encoded 12S RNA (MT-RNR1) and the mitochondrially encoded tRNA serineucn (MT-TS1). The A1555G mutation in MT-RNR1 gene is a frequent cause of deafness in different countries. AIM: The aim of this work was to investigate the frequency of the A1555G mutation in the MT-RNR1 gene in the mitochondrial DNA in Brazilians individuals with nonsyndromic deafness, and listeners. MATERIALS AND METHODS: DNA samples were submitted to polymerase chain reaction and to posterior digestion with the Hae III enzyme. RESULTS: Seventy eight (78) DNA samples of deaf individuals were analyzed; 75 showed normality in the region investigated, two samples (2.5%) showed the T1291C substitution, which is not related to the cause of deafness, and one sample (1.3%) showed the A1555G mutation. Among the 70 non-impaired individuals no A1555G mutation or T1291C substitution was found. CONCLUSION: We can affirm that A1555G mutation is not prevalent, or it must be very rare in normal-hearing subjects in the State of Paraná, the south region of Brazil. The A1555G mutation frequency (1.3%) found in individual with nonsyndromic deafness is similar to those found in other populations, with nonsyndromic deafness. Consequently, it should be examined in deafness diagnosis. The investigation of the A1555G mutation can contribute towards the determination of the nonsyndromic deafness etiology, hence, contributing to the correct genetic counseling process.