Dengue Virus Type 4 Phylogenetics in Brazil 2011: Looking beyond the Veil

Dengue Fever and Dengue Hemorrhagic Fever are diseases affecting approximately 100 million people/year and are a major concern in developing countries. In the present study, the phylogenetic relationship of six strains of the first autochthonous cases of DENV-4 infection occurred in Sao Paulo State, Parana State and Rio Grande do Sul State, Brazil, 2011 were studied. Nucleotide sequences of the envelope gene were determined and compared with sequences representative of the genotypes I, II, III and Sylvatic for DEN4 retrieved from GenBank. We employed a Bayesian phylogenetic approach to reconstruct the phylogenetic relationships of Brazilian DENV-4 and we estimated evolutionary rates and dates of divergence for DENV-4 found in Brazil in 2011. All samples sequenced in this study were located in Genotype II. The studied strains are monophyletic and our data suggest that they have been evolving separately for at least 4 to 6 years. Our data suggest that the virus might have been present in the region for some time, without being noticed by Health Surveillance Services due to a low level of circulation and a higher prevalence of DENV-1 and DENV- 2

Febre amarela silvestre: estudo clínico e laboratorial, enfatizando a viremia, de um caso humano

The authors report the clinical, laboratorial and epidemiological aspects of a human case of jungle yellow fever. The patient suffered from fever, chills, sweating, headaches, backaches, myalgia, epigastric pains, nausea, vomiting, diarrhea and prostration. He was unvaccinated and had been working in areas where cases of jungle yellow fever had been confirmed. Investigations concerning the yellow fever virus were performed. Blood samples were collected on several days in the course of the illness. Three of these samples (those obtained on days 5,7 and 10) were inoculated into suckling mice in attempt to isolate virus and to titrate the viremia level. Serological surveys were carried out by using the IgM Antibodies Capture Enzyme Linked Immunosorbent Assay (MAC-ELISA), Complement Fixation (CF), Hemagglulinalion Inhibition (HI) and Neutralization (N) tests. The yellow fever virus, recovered from the two first samples and the virus titration, showed high level of viremia. After that, specific antibodies appeared in all samples. The interval between the end of the viremia and the appearance of the antibodies was associated with the worsening of clinical symptoms, including bleeding of the mucous membrane. One must be aware of the risk of having a urban epidemics in areas where Aedes aegypti is found in high infestation indexes.Os autores estudaram um caso humano de febre amarela silvestre, sob os aspectos clínico, laboratorial e epidemiológico. O paciente apresentava febre (39ºC), calafrios, sudorese, cefaléia, dor lombar, mialgia, dor abdominal em epigástrio, náuseas, vômitos, diarréia e prostração. Relatava permanência em área onde foram constatados casos de febre amarela silvestre e não havia histórico de vacinação anterior. Frente às suspeitas que levaram à investigação do vírus da febre amarela, foram colhidas várias amostras de sangue no curso da doença. As amostras do 5º, 7º e 10º dias foram submetidas a provas de isolamento e quantificação do vírus, o que possibilitou o estudo da viremia. Empregando-se os testes de MAC-ELISA (detecção de IgM), Fixação de Complemento (FC), Inibição de Hemaglutinação (IH) e teste de Neutralização (N), foi observada a resposta imune para anticorpos específicos nas amostras do 7º ao 26º dias. Os resultados mostraram que no 5º e 7º dias havia persistência da fase virêmica, com títulos elevados. Ao término desta fase, com o aparecimento de anticorpos específicos, foi observado um agravamento do quadro clínico, com sangramento de mucosas. Os autores alertam para a possibilidade de ocorrerem epidemias urbanas em áreas com alta infestação de Aedes aegypti

New arenavirus isolated in Brazil

Adolfo Lutz Institute. Virus Service. São Paulo, SP, Brazil.Adolfo Lutz Institute. Virus Service. São Paulo, SP, Brazil.Paulista Medical School. Infectious Diseases Clinics. São Paulo, SP, Brazil.Adolfo Lutz Institute. Virus Service. São Paulo, SP, Brazil.Adolfo Lutz Institute. Virus Service. São Paulo, SP, Brazil.Adolfo Lutz Institute. Virus Service. São Paulo, SP, Brazil.Ministério da Saúde. Fundação Nacional de Saúde. Instituto Evandro Chagas. Belém, PA, Brasil.Ministério da Saúde. Fundação Nacional de Saúde. Instituto Evandro Chagas. Belém, PA, Brasil.Pan American Health Organization. Communicable Diseases Program. Washington, DC, USA.World Health Organization. Microbiology and Immunology Support Section. Geneva, Switzerland.Yale University. School of Medicine. Department of Epidemiology and Public Health. Yale Arbovirus Research Unit. New Haven, CT.Yale University. School of Medicine. Department of Epidemiology and Public Health. Yale Arbovirus Research Unit. New Haven, CT.US Army Medical Research Institute of Infectious Diseases. Virology Division. Frederick, Maryland, USA.Yale University. School of Medicine. Department of Epidemiology and Public Health. Yale Arbovirus Research Unit. New Haven, CT.A new arenavirus, called Sabiá, was isolated in Brazil from a fatal case of haemorrhagic fever initially thought to be yellow fever. Antigenic and molecular characterisation indicated that Sabiá virus is a new member of the Tacaribe complex. A laboratory technician working with the agent was also infected and developed a prolonged, non-fatal influenza-like illness. Sabiá virus is yet another arenavirus causing human disease in South America

Detail of the Envelope gene MCC tree.

<p>Bolded numbers above branchs are the estimated replacement rates for each sample. The acceleration observed in this terminal branch ma be indicative of a recent introduction of the virus in a previously naïve population.</p

DENV-4 virus strains included in phylogenetic analysis of envelope gene.

<p>* this study.</p

Envelope gene MCMC tree.

<p>The internal nodes were inferred using a Markov Chain Monte Carlo (MCMC) Bayesian approach under a GTR model with Gamma-distributed rate variation (<i>γ</i>) and a proportion of invariable sites (I), using a relaxed (uncorrelated lognormal) molecular clock. Four independent MCMC runs of four chains each were run for 10 millions generations. The highlighted sector indicates the position of the studied strains.</p