An overview of Zika virus genotypes and their infectivity

ABSTRACT Zika virus (ZIKV) is an enveloped, single-stranded RNA arbovirus belonging to the genus Flavivirus. It was first isolated from a sentinel monkey in Uganda in 1947. More recently, ZIKV has undergone rapid geographic expansion and has been responsible for outbreaks in Southeast Asia, the Pacific Islands, and America. In this review, we have highlighted the influence of viral genetic variants on ZIKV pathogenesis. Two major ZIKV genotypes (African and Asian) have been identified. The Asian genotype is subdivided into Southwest Asia, Pacific Island, and American strains, and is responsible for most outbreaks. Non-synonymous mutations in ZIKV proteins C, prM, E, NS1, NS2A, NS2B, NS3, and NS4B were found to have a higher prevalence and association with virulent strains of the Asian genotype. Consequently, the Asian genotype appears to have acquired higher cellular permissiveness, tissue persistence, and viral tropism in human neural cells. Therefore, mutations in specific coding regions of the Asian genotype may enhance ZIKV infectivity. Considering that mutations in the genomes of emerging viruses may lead to new virulent variants in humans, there is a potential for the re-emergence of new ZIKV cases in the future.

DEFB1 gene polymorphisms and tuberculosis in a Northeastern Brazilian population

Abstract β-Defensin-1, an antimicrobial peptide encoded by the DEFB1 gene, is known to play an important role in lung mucosal immunity. In our association study we analyzed three DEFB1 functional polymorphisms -52G>A (rs1799946), -44C>G (rs1800972) and -20G>A (rs11362) in 92 tuberculosis patients and 286 healthy controls, both from Northeast Brazil: no association was found between the studied DEFB1 polymorphisms and the disease. However we cannot exclude that this lack of association could be due to the low number of subjects analyzed, as suggested by the low statistical power achieved for the three analyzed SNPs (values between 0.16 and 0.50).

NLRP3 polymorphism is associated with protection against human T-lymphotropic virus 1 infection

Inter-individual heterogeneity in the response to human T-lymphotropic virus 1 (HTLV-1) infection has been partially attributed to host genetic background. The antiviral activity of the inflammasome cytoplasmic complex recognises viral molecular patterns and regulates immune responses via the activation of interleukin (IL)-1 family (IL-1, IL-18 and IL-33) members. The association between polymorphisms in the inflammasome receptors NLRP1 and NLRP3 and HTLV-1 infection was evaluated in a northeastern Brazilian population (84 HTLV-1 carriers and 155 healthy controls). NLRP3 rs10754558 G/G was associated with protection against HTLV-1 infection (p = 0.012; odds ratio = 0.37). rs10754558 affects NLRP3 mRNA stability; therefore, our results suggest that higher NLRP3 expression may augment first-line defences, leading to the effective protection against HTLV-1 infection.

Fequency distribution of HLA DQ2 and DQ8 in celiac patients and first-degree relatives in Recife, northeastern Brazil

AIMS: The aim of this study was to evaluate the frequencies of the HLA genotypes DQ2 and DQ8 and the alleles A1*05, A1*0201, B1*0201 and B1*0302 in individuals with celiac disease in Recife, northeastern Brazil. METHODS: HLA DQ2 and DQ8 genotyping was performed for 73 individuals with celiac disease and 126 first-degree relatives with negative transglutaminase serology. The alleles DQA1*05, DQA1*0201, DQB1*02 and DQB1*0302 were identified by sequencing using specific primers and the EU-DQ kit from the Eurospital Laboratory, Trieste, Italy and double-checked by the All Set SPP kit (Dynal). RESULTS: Among the 73 cases, 50 (68.5 percent) had the genotype DQ2, 13 (17.8 percent) had DQ8, 5 (6.8 percent) had DQ2 and DQ8, and 5 did not have any of these genotypes. Among the 5 negative individuals, four had the B1*02 allele and one did not have any of the alleles studied. B1*02 was the most frequent allele in both groups (94 percent in the patients and 89 percent in the control relatives). CONCLUSIONS: In this study, celiac disease was associated with the genotypes DQ2 and DQ8. DQ2 predominated, but the distribution of the frequencies was different from what has been found in European populations and was closer to what has been found in the Americas. The high frequencies of the HLA genotypes DQ2 and DQ8 that were found in first-degree relatives would make it difficult to use these HLA genotypes for routine diagnosis of celiac disease in this group.

Principles and applications of polymerase chain reaction in medical diagnostic fields: a review: [revision] / Princípios e aplicações da reação em cadeia de Polimerase em áreas médicas diagnósticas: uma revisão: [revisão]

Recent developments in molecular methods have revolutionized the detection and characterization of microorganisms in a broad range of medical diagnostic fields, including virology, mycology, parasitology, microbiology and dentistry. Among these methods, Polymerase Chain Reaction (PCR) has generated great benefits and allowed scientific advancements. PCR is an excellent technique for the rapid detection of pathogens, including those difficult to culture. Along with conventional PCR techniques, Real-Time PCR has emerged as a technological innovation and is playing an ever-increasing role in clinical diagnostics and research laboratories. Due to its capacity to generate both qualitative and quantitative results, Real-Time PCR is considered a fast and accurate platform. The aim of the present literature review is to explore the clinical usefulness and potential of both conventional PCR and Real-Time PCR assays in diverse medical fields, addressing its main uses and advances.

O advento dos métodos moleculares tem, nos últimos anos, revolucionado a detecção e caracterização dos microorganismos em diversas áreas médicas diagnósticas, tais como virologia, micologia, parasitologia, microbiologia e odontologia. Dentre as técnicas baseadas em biologia molecular, a PCR (Polymerase Chain Reaction) trouxe enormes benefícios e desenvolvimentos científicos, se mostrando como um excelente caminho para a rápida detecção de patógenos, até mesmo aqueles de difícil cultivo. Derivada da PCR convencional, a PCR em Tempo Real se mostra como uma inovação tecnológica e vem conquistando espaço nos diagnósticos clínicos e nos laboratórios de pesquisa por apresentar a capacidade de gerar, além de resultados qualitativos, resultados quantitativos, se mostrando de forma mais rápida e precisa. Este trabalho de revisão tem por objetivo explorar a utilidade clínica da técnica de PCR convencional e em Tempo real nas diversas áreas médicas supracitadas, abrangendo seus principais usos e avanços, direcionando para o cotidiano profissional.

Chlamydia infection in patients with and without cervical intra-epithelial lesions tested by real-time PCR vs. direct immunofluorescence

This study compares the detection rates of Chlamydia trachomatis by two techniques, direct immunofluorescence (IMF) and real time polymerase chain reaction (PCR), in patients with and without intra-epithelial cervical lesions (SIL) in Recife. We conducted a transversal study involving 35 women with SIL and 35 without SIL attended at Ambulatório Especializado da Mulher, Recife, Brazil. They were tested for Chlamydia trachomatis using two techniques, direct IMF or real time PCR. The rates of Chlamydia trachomatis detection were compared and the association with intra-epithelial cervical lesions was determined using the chi-square test at a 5 percent level of significance. Concordance between the tests was evaluated using kappa. The global prevalence of Chlamydia infection was 47.1 percent by direct IMF and 58.6 percent by real time PCR. A significant association was observed between Chlamydia diagnosis and presence of intra-epithelial cervical lesions, with about 80 percent positive results by direct IMF and 77.1 percent by real time PCR. However, the detected rate of infection with Chlamydia trachomatis was significantly greater in patients without intra-epithelial cervical lesions tested by real time PCR (40 percent) when compared to direct IMF (14.3 percent). The concordance between the tests was weak, with a kappa coefficient of 0.4. Both real time PCR and direct IMF detected elevated rates of Chlamydia infection in patients with intra-epithelial cervical lesions (80 percent) but the tests were discordant when patients without cervical lesions were tested, possibly because sensitivity of real time PCR is greater.