Milene Silveira Ferreira

Seroepidemiological monitoring in sentinel animals and vectors as part of arbovirus surveillance in the state of Mato Grosso do Sul, Brazil

INTRODUCTION From February-September 2010, seroepidemiological surveys were conducted on non-human primates and transmitter vector capture was used to investigate the possible circulation of arboviruses in the municipalities of Bonito, Campo Grande, and Jardim, State of Mato Grosso do Sul, Brazil. METHODS A total of 65 primates from the wild and captivity were used, and potential vectors were captured using Castro and dip nets. Serum samples were tested at the Instituto Evandro Chagas, State of Pará, using the hemagglutination inhibition test to detect total antibodies against 19 different arboviruses. Virus isolation was attempted from serum samples and arthropod suspensions using newborn mice and the C6/36 cell line clone. In addition, identification of the vector species was conducted. RESULTS From the 19 serum samples from Campo Grande, 1 sample had a 1:20 titer for Flavivirus. From the 35 samples collected in Bonito, 17 samples had antibodies to arboviruses, 4 (11.4%) were positive for Alphavirus, and 5 (14.2%) were positive for Flavivirus. Monotypic reactions were observed for the Mayaro (n = 10) and Oropouche (n = 5) viruses, and 6 (17.1%) samples had titers for >1 virus. We captured 120 Culicidae individuals that were potential arbovirus transmitters in Jardim; however, all the samples were negative for the viruses. CONCLUSIONS Mato Grosso do Sul has a variety of vertebrate hosts and transmission vectors, thereby providing ideal conditions for the emergence or reemergence of arboviruses, including some pathogenic to human beings.

Callithrix penicillata: A feasible experimental model for dengue virus infection

Although the murine models have the feasibility to reproduce some signs of dengue Virus (DENV) infection, the use of isogenic hosts with polarized immune response patterns does not reproduce the particularities of human disease. Our goal was to investigate the kinetics of peripheral blood biomarkers in immunocompetent Callithrix penicillata non-human primates subcutaneously infected with DENV-3. The viral load of infected animals was determinated by quantitative real time PCR. Measurements of DENV-3/IgM were performed, and several parameters were assessed by hemogram: red blood cells count, hemoglobin, hematocrit, white blood cells count, neutrophils, monocytes, lymphocytes, and platelets count. The coagulogram was performed by prothrombin time (PT), and activated partial thromboplastin time (APTT) assays. The renal function was monitored by urea and creatinine, and the liver function by the aspartate (AST), and alanine (ALT) aminotransferases. Also, the level of the cytokines IL-6, TNF-α, IL-2, IFN-γ, IL-4 and IL-5 was quantified during the experimental study. Data analysis was performed considering relevant differences when baseline fold changes were found outside from 0.75 to 1.5 range. Our data demonstrated that infected animals presented relevant signs of dengue disease, including peaks of viremia at 5 days-post-infection (dpi), peaks of anti-DENV-3 IgM at 15 dpi and hemaglutination inhibition assay (HIA) from 15 to at 60 dpi. Despite early monocytosis, slight neutrophilia and lymphocytosis, animals developed persistent leucopenia starting at 4 dpi. Anemia episodes were steady at 3-4 dpi. Patent thrombocytopenia was observed from 1 to 15 dpi with sporadic decrease of APTT. A substantial increase of ALT and AST was observed with higher peak at 4 dpi. Moreover, early increases of TNF-alpha and IFN-gamma besides late increase of IFN-gamma were observed. The analysis of biomarkers network pointed out two relevant strong axes during early stages of dengue fever, a protective axes TNF-alpha/Lymphocytes/Platelets, and a pathological IL-2/IL-6/Viremia/Monocyte/PT bond. Later on, the biomarker network highlighted the interaction IFN-gamma/PLT/DENV-3(IgM;HAI)/PT, and the involvement of type-2 cytokines (IL-4; IL-5). Our findings demonstrated that C. penicillata is a feasible experimental model for dengue virus infection, which could be useful to pathogenesis studies, discovery of novel antiviral drugs as well as to evaluate vaccine candidates against DENV.

Detection of antibodies to Oropouche virus in non-human primates in Goiânia City, Goiás

INTRODUCTION Arboviruses are associated with human disease, and non-human primates (NHPs) are important primary hosts. This study shows the detection of antibodies to Oropouche virus (OROV) in NHPs either living in urban parks or acclimatized at the Wild Animal Screening Center, Goiânia city. METHODS Fifty blood samples were analyzed by hemagglutination-inhibition and neutralization assays. RESULTS Two monkeys (Alouatta caraya) had antibodies to OROV by both techniques. CONCLUSIONS This is the first report demonstrating the detection of OROV antibodies in Goiás State and may represent the introduction/circulation of OROV in the region and a potential risk to the human population.

Antibody-enhanced dengue disease generates a marked CNS inflammatory response in the black-tufted marmoset Callithrix penicillata.

Severe dengue disease is often associated with long‐term neurological impairments, but it is unclear what mechanisms are associated with neurological sequelae. Previously, we demonstrated antibody‐enhanced dengue disease (ADE) dengue in an immunocompetent mouse model with a dengue virus 2 (DENV2) antibody injection followed by DENV3 virus infection. Here we migrated this ADE model to Callithrix penicillata. To mimic human multiple infections of endemic zones where abundant vectors and multiple serotypes co‐exist, three animals received weekly subcutaneous injections of DENV3 (genotype III)‐infected supernatant of C6/36 cell cultures, followed 24 h later by anti‐DENV2 antibody for 12 weeks. There were six control animals, two of which received weekly anti‐DENV2 antibodies, and four further animals received no injections. After multiple infections, brain, liver, and spleen samples were collected and tissue was immunolabeled for DENV3 antigens, ionized calcium binding adapter molecule 1, Ki‐67, TNFα. There were marked morphological changes in the microglial population of ADE monkeys characterized by more highly ramified microglial processes, higher numbers of trees and larger surface areas. These changes were associated with intense TNFα‐positive immunolabeling. It is unclear why ADE should generate such microglial activation given that IgG does not cross the blood‐brain barrier, but this study reveals that in ADE dengue therapy targeting the CNS host response is likely to be important.

Clinical and serological tests for arboviruses in free-living domestic pigeons (Columba livia)

BACKGROUND In this study, we evaluated the role of free-living domestic pigeons (Columba livia) as a reservoir of arboviruses in the city of Belém, state of Pará, Brazil. We investigated the presence of antibodies against the most prevalent arboviruses. OBJECTIVES This study was aimed at evaluating some clinical and physical parameters of domestic pigeons, including the presence of antibodies to Amazon-endemic arboviruses. METHODS Eighty-five healthy pigeons were captured in Mangal das Garças Park, in Belém, and were bled. Upon capture, the birds were subjected to a clinical examination in search of alterations that could indicate the presence of arboviruses. Blood samples were converted to serum and tested using the haemagglutination inhibition (HI) technique with a panel of 19 antigens of arboviruses circulating in the Amazon. The confirmation assay for the positive reactions to the viral species tested by HI was a neutralisation test in new-born Swiss albino mice (Mus musculus) [mouse neutralisation test (MNT)]. FINDINGS A total of 10 (11.8%) serum samples tested positive for antiflavivirus antibodies by HI. All the samples positive for the HI test were subjected to MNT for detection of viruses and yielded negative results (logarithmic neutralisation index < 1.7). MAIN CONCLUSION The results represent the first serological detection of antiarbovirus antibodies in domestic pigeons as potential hosts of arboviruses in Brazil. The detection of haemagglutination-inhibiting antibodies against genus Flavivirus indicated that there was recent contact between the analysed domestic pigeons and these arboviruses. Further studies are needed to evaluate the role of free-living pigeons in the maintenance cycle and spread of arboviruses in the Amazon.

Application of time series control charts to model and monitor the seasonality of norovirus

INTRODUCTION: Time series control charts are tools that allow one to identify the nature of certain variations in a process, whether they are variations due to common causes, deemed of little importance, or to special causes. The goal of this study was to apply time series control charts to analyse the seasonality observed in norovirus infections in children admitted from May 2008 to April 2011 to a paediatric hospital in Belem City, Para State, Amazon Region, Brazil. MATERIALS AND METHODS: To apply the models, it was necessary to make the stationary series, which was performed by applying the first difference of monthly norovirus positivity rates. To construct the charts, KolmogorovSmirnov normality test was used to verify if the data were normally distributed. RESULTS: During the three years, the highest prevalence was observed between September and October 2008 (63.6%) and February 2010 (62.1%). The study series was under statistical control, with a tendency for stability and no evidence of seasonality or cycle. No outlying values were observed, which strongly suggest that no atypical factor that could affect the stability of the series was present. CONCLUSION: This study demonstrates the applicability of time series control charts in the seasonality analysis of several pathogens studied in the biomedical sciences, and it is the first time that this statistical method has been applied to assess the time distribution of norovirus.