Reverse Genetics of Dengue Virus.

Dengue virus (DENV) is one of the most important and widespread arthropod-borne viruses, causing millions of infections over the years. Considering its epidemiological importance, efforts have been directed towards understanding various aspects of DENV biology, which have been facilitated by the development of different molecular strategies for engineering viral genomes, such as reverse genetics approaches. Reverse genetic systems are a powerful tool for investigating virus-host interaction, for vaccine development, and for high-throughput screening of antiviral compounds. However, stable manipulation of DENV genomes is a major molecular challenge, especially when using conventional cloning systems. To circumvent this issue, we describe a simple and efficient yeast-based reverse genetics system to recover infectious DENV clones.

Antibody Response to the SARS-CoV-2 Spike and Nucleocapsid Proteins in Patients with Different COVID-19 Clinical Profiles.

The first case of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), in Brazil was diagnosed on February 26, 2020. Due to the important epidemiological impact of COVID-19, the present study aimed to analyze the specificity of IgG antibody responses to the S1, S2 and N proteins of SARS-CoV-2 in different COVID-19 clinical profiles. This study enrolled 136 individuals who were diagnosed with or without COVID-19 based on clinical findings and laboratory results and classified as asymptomatic or as having mild, moderate or severe disease. Data collection was performed through a semistructured questionnaire to obtain demographic information and main clinical manifestations. IgG antibody responses to the S1 and S2 subunits of the spike (S) protein and the nucleocapsid (N) protein were evaluated using an enzyme-linked immunosorbent assay (ELISA) according to the manufacturer's instructions. The results showed that among the participants, 87.5% (119/136) exhibited IgG responses to the S1 subunit and 88.25% (120/136) to N. Conversely, only 14.44% of the subjects (21/136) displayed S2 subunit responses. When analyzing the IgG antibody response while considering the different proteins of the virus, patients with severe disease had significantly higher antibody responses to N and S1 than asymptomatic individuals (p ≤ 0.0001), whereas most of the participants had low antibody titers against the S2 subunit. In addition, individuals with long COVID-19 showed a greater IgG response profile than those with symptomatology of a short duration. Based on the results of this study, it is concluded that levels of IgG antibodies may be related to the clinical evolution of COVID-19, with high levels of IgG antibodies against S1 and N in severe cases and in individuals with long COVID-19.

Bioprospection and Selection of Peptides by Phage Display as Novel Epitope-Based Diagnostic Probes for Serological Detection of HTLV-1 and Use in Future Vaccines.

Human T-lymphotropic virus 1 (HTLV-1) is endemic worldwide and the infection results in severe diseases, including Adult T-cell Leukemia (ATL) and HTLV-1 associated myelopathy (HAM). There are some limitations of employing the present commercial serological assays for both diagnostic and epidemiological purposes in different geographical areas of the Brazil, such as the Amazon Region. Currently, methods for diagnosis are usually expensive to adapt for routine use. The aim of this work was to identify and characterize specific ligands to IgG that mimic HTLV-1 epitopes through the Phage Display technique, which could be used for diagnosis and as future vaccine candidates. Initially, IgG from 10 patients with HTLV-1 and 20 negative controls were covalently coupled to protein G-magnetic beads. After biopanning, genetic sequencing, bioinformatics analysis and Phage-ELISA were performed. The technique allowed the identification of 4 clones with HTLV-1 mimetic peptides, three aligned with gp46, A6 (SPYW), B6 (SQLP) and D7 (PLIL), and one with the protease and Tax, A8 (SPPR). Clones A6 and B6 showed higher values of accessibility, antigenicity and hydrophilicity. The reactivity of the clones evaluated by the Receiver Operating Characteristic (ROC) curve showed that the B6 clone had the highest Area Under Curve (0.83) and sensitivity and specificity values (both were 77.27 %; p < 0.001). The study showed that the Phage Display technique is effective for the identification of HTLV-1-related peptides. Clone B6 indicated to be a good marker for bioprospecting diagnostic test for HTLV-1 infection and could be used as a possible vaccine candidate for future studies.

Prevalence of High Risk HPV in HIV-Infected Women From Belém, Pará, Amazon Region of Brazil: A Cross-Sectional Study.

Human papillomavirus (HPV) is the most common sexually transmitted infection in the world. Several studies have shown a higher prevalence of HPV infection in HIV-infected women. The aim of this study was to determine the prevalence and the genotype diversity of HPV infection in HIV-infected women. From April 2010 to December 2012 cervical specimens were collected from 169 HIV-infected women who screening for cervical cancer at Reference Unit in Belém. The detection of HPV infection was performed by nested PCR and HPV type was performed using a commercial system. The prevalence of HPV infection was 63.3%. Of the 47 genotyped samples, 40.4% was found positive for high risk-HPV 16 and 12.8% for high risk-HPV 52. HPV infection was predominant in the group of women with no incidence of cytological abnormalities and more prevalent in women of reproductive age, unmarried, low education level, and who reported use condoms during sexual intercourse. It was observed an association between HPV infection and independent variables, such as condom use, multiple sexual partners, and history of sexually transmitted diseases. High-risk types of HPV infection were prevalent in our study. Infection with multiple high-risk HPV genotypes may potentiate the development of cervical cancer in HIV-infected women.

STING and cGAS gene expressions were downregulated among HIV-1-infected persons after antiretroviral therapy.

BACKGROUND: The HIV-1 epidemic is still considered a global public health problem, but great advances have been made in fighting it by antiretroviral therapy (ART). ART has a considerable impact on viral replication and host immunity. The production of type I interferon (IFN) is key to the innate immune response to viral infections. The STING and cGAS proteins have proven roles in the antiviral cascade. The present study aimed to evaluate the impact of ART on innate immunity, which was represented by STING and cGAS gene expression and plasma IFN-α level. METHODS: This cohort study evaluated a group of 33 individuals who were initially naïve to therapy and who were treated at a reference center and reassessed 12 months after starting ART. Gene expression levels and viral load were evaluated by real-time PCR, CD4+ and CD8+ T lymphocyte counts by flow cytometry, and IFN-α level by enzyme-linked immunosorbent assay. RESULTS: From before to after ART, the CD4+ T cell count and the CD4+/CD8+ ratio significantly increased (p < 0.0001), the CD8+ T cell count slightly decreased, and viral load decreased to undetectable levels in most of the group (84.85%). The expression of STING and cGAS significantly decreased (p = 0.0034 and p = 0.0001, respectively) after the use of ART, but IFN-α did not (p = 0.1558). Among the markers evaluated, the only markers that showed a correlation with each other were STING and CD4+ T at the time of the first collection. CONCLUSIONS: ART provided immune recovery and viral suppression to the studied group and indirectly downregulated the STING and cGAS genes. In contrast, ART did not influence IFN-α. The expression of STING and cGAS was not correlated with the plasma level of IFN-α, which suggests that there is another pathway regulating this cytokine in addition to the STING-cGAS pathway.

Detection of Human polyomavirus 2 (HPyV2) in oyster samples in northern Brazil.

BACKGROUND: Human polyomavirus 2 (HPyV2 or JCPyV) is persistent in the environment due to its excretion in urine and feces; it is detected in samples of wastewater, surface water and drinking water. A lack of basic sanitation and sewage collection results in the presence of this virus in food, especially in oysters, since they are bioaccumulators and are consumed in their natural form, thus posing a risk to human health. METHODS: This study investigated the frequency of HPyV2 in samples of oysters marketed in northeastern Pará State, Brazil, and optimized a real-time PCR (qPCR) protocol for the detection of an endogenous oyster control. A total of 217 oysters in 22 pools from five municipalities in the state of Pará were analyzed. Samples underwent dissection and total maceration of oyster tissue using a viral concentration technique, followed by DNA extraction with phenol-chloroform and amplification of the VP1 region for molecular detection via qPCR. RESULTS: HPyV2 was detected in 18.2% (4/22) of the pooled samples, with frequencies of 25, 20, 20 and 16% in the municipalities of Salinópolis, Augusto Corrêa, São Caetano de Odivelas and Curuçá, respectively. Notably, the sample pool from the municipality of Bragança did not have detectable HPyV2 and this was the only sampled location with a water treatment station. In this study, Crassostrea genus-specific primers (AFL52 ribosomal RNA gene) of oyster were developed for use as an endogenous control in the qPCR analysis, which will be useful for future studies. CONCLUSIONS: The detection of HPyV2 in oyster samples commercialized in the state of Pará shows the circulation of this virus in the studied municipalities. Thus, it is necessary to implement measures for improving sewage collection and basic sanitation to avoid contamination of water and food with HPyV2.

Development and characterization of a packaging cell line for pseudo-infectious yellow fever virus particle generation.

INTRODUCTION: Pseudo-infectious yellow fever viral particles (YFV-PIVs) have been used to study vaccines and viral packaging. Here, we report the development of a packaging cell line, which expresses the YFV prM/E proteins. METHODS: HEK293 cells were transfected with YFV prM/E and C (84 nt) genes to generate HEK293-YFV-PrM/E-opt. The cells were evaluated for their ability to express the heterologous proteins and to package the replicon repYFV-17D-LucIRES, generating YFV-PIVs. RESULTS: The expression of prM/E proteins was confirmed, and the cell line trans-packaged the replicon for recovery of a reporter for the YFV-PIVs. CONCLUSIONS: HEK293-YFV-prM/E-opt trans-packaging capacity demonstrates its possible biotechnology application.

Development and characterization of a packaging cell line for pseudo-infectious yellow fever virus particle generation

Abstract INTRODUCTION: Pseudo-infectious yellow fever viral particles (YFV-PIVs) have been used to study vaccines and viral packaging. Here, we report the development of a packaging cell line, which expresses the YFV prM/E proteins. METHODS: HEK293 cells were transfected with YFV prM/E and C (84 nt) genes to generate HEK293-YFV-PrM/E-opt. The cells were evaluated for their ability to express the heterologous proteins and to package the replicon repYFV-17D-LucIRES, generating YFV-PIVs. RESULTS: The expression of prM/E proteins was confirmed, and the cell line trans-packaged the replicon for recovery of a reporter for the YFV-PIVs. CONCLUSIONS: HEK293-YFV-prM/E-opt trans-packaging capacity demonstrates its possible biotechnology application.

Full-length infectious clone of a low passage dengue virus serotype 2 from Brazil

Full-length dengue virus (DENV) cDNA clones are an invaluable tool for many studies, including those on the development of attenuated or chimeric vaccines and on host-virus interactions. Furthermore, the importance of low passage DENV infectious clones should be highlighted, as these may harbour critical and unique strain-specific viral components from field-circulating isolates. The successful construction of a functional Brazilian low passage DENV serotype 2 full-length clone through homologous recombination reported here supports the use of a strategy that has been shown to be highly useful by our group for the development of flavivirus infectious clones and replicons.

Full-length infectious clone of a low passage dengue virus serotype 2 from Brazil.

Full-length dengue virus (DENV) cDNA clones are an invaluable tool for many studies, including those on the development of attenuated or chimeric vaccines and on host-virus interactions. Furthermore, the importance of low passage DENV infectious clones should be highlighted, as these may harbour critical and unique strain-specific viral components from field-circulating isolates. The successful construction of a functional Brazilian low passage DENV serotype 2 full-length clone through homologous recombination reported here supports the use of a strategy that has been shown to be highly useful by our group for the development of flavivirus infectious clones and replicons.

Identificação de epítopos de célula B na glicoproteína-E do envelope do vírus dengue sorotipo 3 / Identification of B-cell epitopes in the envelope glycoprotein of dengue virus type 3

As infecções pelo vírus dengue têm se tornado um problema crescente de Saúde Pública em regiões tropicais e subtropicais do mundo. O vírus pertence à família Flaviviridae com quatro sorotipos antigenicamente distintos (DENV-1 a DENV-4). Uma possível estratégia para evitar a patogenia associada com uma vacina para o dengue (que deve ser tetravalente), seria a construção de uma vacina quimérica composta de epítopos críticos selecionados dos quatro sorotipos. A maioria dos epítopos envolvidos na neutralização do vírus está presente na glicoproteína E do envelope, que é a maior proteína de superfície da partícula viral. O objetivo deste trabalho foi identificar epítopos de célula B na glicoproteína E do vírus dengue sorotipo 3. Para o mapeamento de epítopos imunodominantes, noventa e cinco peptídeos (15-mers cada, sobreposição de 10) foram sintetizados (Synpep, California-USA), a partir da sequência de 490 aminoácidos da glicoproteína E do envelope do DENV-3, de cepa circulante no Brasil. Estes peptídeos foram testados por ELISA contra um pool de soros de pacientes positivos e negativos para dengue, coletados durante a fase de convalescença da infecção por DENV-3. Os resultados mostraram que os soros de humanos reagiram com onze, dos noventa e cinco peptídeos testados, distribuídos em 5 regiões com aminoácidos na posições 51-65 (peptídeo 11), 71-90 (peptídeos 15 e 16), 131-170 (peptídeos 27, 28, 29, 30, 31 e 32), 196-210 (peptídeo 40) e 246-260 (peptídeo 50). A análise da curva ROC mostrou que, dentre os peptídeos identificados, nove seriam capazes de diferenciar entre pacientes com DENV-3 de pacientes não-dengue e três capazes de diferenciar a infecção por DENV-3 daquelas por outros sorotipos virais (DENV-1 e DENV-2). Os epítopos imunodominantes aqui descritos, junto com outros epítopos bem documentados, são potencialmente relevantes para o desenho de uma vacina para o vírus dengue e para o desenvolvimento de kits de diagnóstico específicos.

Prevalência do anti-HCV em pacientes soropositivos para o HIV / Prevalence anti-HCV among HIV seropositive patients

Objetivo: determinar a prevalência do anti-HCV em pacientes portadores do HIV. Método: a pesquisa do anti-HCV foi realizada pelo método ELISA de 3ª geração (Hepatitis C anti-HCV da Wiener lab.). Resultados: a co-infecção encontrada foi de 4,1% (14/343). Dos co-infectados, 64,2%(9/14) eram do sexo masculino e a faixa etária variou de 30 a 39 anos, 64,2%(9/14). Conclusão: a prevalência da co-infecção HCV/HIV, neste estudo, foi baixa se comparada com outras regiões do Brasil e do mundo.

Objective: To determine the prevalence of anti-HCV among HIV seropositive patients. Methods: HCV antibodies were detected by ELlSA (Hepatitis C anti-HCV, Wiener Lab.). Results: The co-infection found was 4,1%(14/343). Among co-infected, 64,2%(9/14) were male sex and age varied from 30 a 39 years with 64,2% (9/14). Conclusion: The prevalence of HCV/H1V co-infection in that study was low in compared with others regions of Brazil and the world.

Prevalência de anticorpos da classe IgG para citomegalovírus em portadores de vitiligo / Prevalence of IgG antibodies for cytomegalovirus among patients with vitiligo

Introdução: o vitiligo é uma doença cuja etiologia não se encontra bem estabelecida, embora fatores de ordem genética, neural, autocitotóxica e autoimune tenham sido propostos. Pesquisas recentes sugerem que o vitiligo é provavelmente uma doença heterogênea com múltiplas causas. Evidências indiretas de que infecções virais podem contribuir para a patogogênese do vitiligo incluem: síndromes semelhantes à influenza precedendo o início do vitiligo; a doença ocorrendo em pacientes com a síndrome da imunodeficiência adquirida (SIDA) e o DNA do citomegalovírus (CMV) identificado pela reação em cadeia da polimerase (PCR) em pacientes portadores de vitiligo. Objetivo: Determinar a prevalência de anticorpos para o CMV, entre os pacientes portadores do vitiligo, comparando com uma população controle.Método: Anticorpos para o CMV foram pesquisados pelo método imunoenzimático (ELISA) em 70 portadores de vitiligo e em 256 pacientes-controle, provenientes do Setor de Dermatologia do Hospital das Clínicas da UFPE, no período de novembro de 1999 a junho de 2000.Resultados: Os resultados mostraram que 70 por cento dos pacientes com vitiligo foram positivos para o CMV, enquanto que nos pacientes controle, a presença de IgG anti-CMV foi de 77,7 por cento. Não houve diferença estatisticamente significante mesmo após ajustes para os possíveis fatores de confusão.Conclusão: Os autores concluem que a sorologia parece não ser bom marcador para estabelecer a possível relação entre CMV e o vitiligo. Novo estudos deverão ser realizados utilizando técnicas de biologia molecular (PCR) procurando identificar o DNA viral em lesões vitiliginosas