Proposta da utilização de adenovírus como indicadores de contaminação viral humana em ostras de cultivo

Dissertação (mestrado) - Universidade Federal de Santa Catarina. Programa de Pós-Graduação em Biotecnologia.Com o grande crescimento da maricultura em Santa Catarina, tornou-se necessário verificar mais profundamente a qualidade sanitária destes animais como também da água onde os mesmos são cultivados. Segundo a nova legislação (CONAMA - 20), a qualidade sanitária dos alimentos de origem marinha deve ser atestada através da ausência de Salmonella sp e de níveis aceitáveis de estafilococus coagulase positiva. Porém, hoje em dia sabe-se que moluscos cultivados em área com níveis aceitáveis de bactérias podem estar contaminados por vírus, já que métodos para remoção de bactérias por depuração, nem sempre removem os demais patógenos contaminantes. Os vírus Norwalk-like (NLV), são mundialmente reconhecidos como a principal causa de surtos de gastroenterites não bacteriana em adultos. Estes vírus têm sido também associados a surtos de gastroenterites associadas ao consumo de moluscos bivalves, já que eles se alimentam através de filtração, podendo bioacumular diversos patógenos em seus tecidos. Os adenovírus (AdVs) humanos são agentes que podem causar infecções oculares, respiratórias e gastrointestinais e são, freqüentemente, detectados em águas de esgoto e do mar, uma vez que todos os sorotipos são liberados através das fezes no meio ambiente. O presente trabalho teve como objetivo padronizar a técnica de RT-PCR para a detecção dos vírus NLV, e as técnicas de PCR, nested-PCR e PCR associado à cultura celular (ICC-PCR) para a detecção dos AdVs em experimentalmente infectadas visando a utilização destes como indicadores de contaminação viral humana no meio ambiente. Também foram coletadas ostras da espécie Crassostrea gigas em três pontos de cultivo de Florianópolis, SC, durante os meses de abril a outubro de 2002 a fim de monitorar a presença natural de adenovírus através dos ensaios de PCR, e nested-PCR. Os resultados obtidos mostraram que a técnica de nested-PCR para detecção de adenovírus em ostras foi mais sensível que a de PCR, sendo que os limites mínimos de vírus detectados foram de 1,2 PFU/g de tecido e 1,2x102 PFU/g de tecido, respectivamente. Este resultado também se repetiu quando as amostras ambientais foram analisadas, onde 90% das amostras foram positivas para adenovírus através da técnica de nested-PCR e nenhuma foi positiva utilizando somente uma reação de amplificação. O ensaio de ICC-PCR demonstrou a mesma sensibilidade que o de PCR para detecção de adenovírus experimentalmente inoculados em ostras. Finalmente, constatou-se que estudos mais aprofundados são necessários para a detecção de NLVs em ostras, uma vez que não foi possível detectá-los em extratos de ostras experimentalmente inoculadas, pelos métodos empregados neste trabalho. O presente trabalho permitiu padronizar as metodologias de PCR e nested-PCR para a utilização de adenovírus como um indicador biológico de contaminação biológica no meio ambiente, visando o monitoramento da sanidade dos moluscos de cultivo

Aplicação de métodos moleculares e de cultivo celular no monitoramento de vírus entéricos no ambiente aquático

Tese (doutorado) - Universidade Federal de Santa Catarina, Programa de Pós-Graduação em Biotecnologia, Florianópolis, 2009.Os vírus entéricos humanos são importantes causas de enfermidades veiculadas através da água. Atualmente, em termos de legislação brasileira, apenas a contagem do número de coliformes é utilizada para determinar a segurança microbiológica de águas tratadas e não tratadas. Os vírus presentes no meio ambiente são, na sua maioria, não adaptados ao cultivo in vitro, tornando-se necessário o desenvolvimento e implementação de métodos que possibilitem a adoção de medidas preventivas para controle de contaminação viral. Assim sendo, os objetivos do presente trabalho foram (I) padronizar e estabelecer metodologias de concentração, detecção, quantificação e viabilidade viral no ambiente aquático; (II) realizar a pesquisa de adenovírus humanos (HAdV), norovírus (NoV) genogrupos GI e GII, rotavírus humanos genogrupo A (RV-A) e vírus da hepatite A (HAV) em águas ambientais e ostras de cultivo durante o período de um ano e (III) avaliar por ensaio de placa de lise a sobrevivência de HAdV infecciosos sorotipos 2 e 41 em águas de superfície e subterrâneas. No estudo de padronização dos métodos foram utilizados como modelos os HAdV e HAV inoculados em águas: destilada, de esgoto tratado, do mar e da lagoa. A melhor eficiência de recuperação viral (100%) foi obtida quando as matrizes de água destilada e de esgoto tratado foram utilizadas. A menor eficiência (10%) foi encontrada para a água do mar. No estudo de campo, águas foram coletadas de 8 locais de Florianópolis, Santa Catarina e ostras (Crassostrea gigas) de duas fazendas de cultivo (norte e sul da Ilha) foram também avaliadas no mesmo período. Os resultados de detecção de genomas virais foram HAdV: 75% (esgoto tratado); 64,2% (águas ambientais); 87,5% (ostras); RV-A: 41,6% (esgoto tratado); 19% (águas ambientais); 8,3% (ostras); HAV: 25% (esgoto tratado); 8,3% (águas ambientais); ausência nas ostras; NoV: 50% (esgoto tratado); 19% (águas ambientais); ausência nas ostras. No estudo de viabilidade viral por PCR integrado a cultura celular (ICC-PCR), confirmou-se positividade de HAdV em: 66,6% (esgoto tratado); 83,8% (águas ambientais); de RV-A: ausência em esgoto tratado e 12,5% (águas ambientais); de HAV: 66,6% (esgoto tratado) e ausência nas águas ambientais. Por PCR quantitativo o número de genomas (gc) de NoV nas águas foram médias de 1,8 x 102 (GI) e 1,0 x 103 gc/L (GII) em esgoto tratado e de 1,1 x 102 (GI) e 8,1 x 103 gc/L (GII) nas águas ambientais. Para HAdV obteve-se médias de: 9,8 x 104 (esgoto tratado); 9,8 x 106 gc/L (águas ambientais) e de 9,1 x 104 (ostras sul da ilha) e 1,5 x 105 gc/g (ostras norte da ilha). Os resultados obtidos indicam uma maior prevalência de HAdV no ambiente aquático, seguido de NoV, RV-A e HAV. No estudo de decaimento de infectividade de HAdV em amostras de água houve uma significativa inativação viral somente ao final das 23 semanas a 19°C para os dois sorotipos de adenovírus testados. Estes resultados demonstram a longa taxa de sobrevivência destes vírus em águas ambientais.Enteric viruses are important cause of gastroenteritis outbreaks transmitted through contaminated water sources. Nowadays, the Brazilian legislation only requires the coliforms counting to determine the microbiologic safety in treated and non treated water. Most viruses present in the aquatic environment are not adaptable to in vitro cultures, becoming necessary to develop and implement methods that could be used in the monitoring and prevention of viral contamination. Therefore, the objectives of this thesis were (I) to standardize and establish methodologies of concentration, detection, quantification and viral viability in the aquatic environment; (II) to access the contamination of human adenovirus (HAdV), norovirus (NoV) genogrups GI e GII, human rotavirus genogrup A (RV-A) and Hepatitis Virus A (HAV) in environmental waters and oysters during one year; (III) to study the survival of infectious HAdV type 2 and 41 in surface and ground waters measured by plaque assay. In the standardization study, HAdV and HAV were used as models and were inoculated in distilled water, treated wastewater, seawater and lagoon water, showing better virus recovery (100%) in distilled water and treated wastewater, and lower recovery (10%) in seawater. In the field study, water samples were collected from 8 sites in Florianopolis, Santa Catarina and oyster samples (Crassostrea gigas) from two oysters' farms (north and south of the Island) were also collected in the same period. The detection results of virus genomes were HAdV: 75% (treated wastewater); 64.2% (environmental waters); 87.5% (oysters); RV-A: 41.6% (treated wastewater); 19% (environmental waters); 8.3% (oysters); HAV: 25% (treated wastewater); 8.3% (environmental waters); absence in oysters; NoV: 50% (treated wastewater); 19% (environmental waters); absence in oysters. In the viability study by integrated cell culture PCR (ICC-PCR), the results confirmed viable HAdV: 66.6% (treated wastewater); 83.3% (environmental waters); RV-A: absence in treated wastewater and 12.5% (environmental waters); HAV: 66.6% (treated wastewater) and absence in environmental waters. By quantitative PCR assays the number of genomes (g.c.) for NoV in waters were averages of 1.8 x 102 (GI) and 1.0 x 103 gc/L (GII) in treated wastewater and 1.1 x 102 (GI) and 8.1 x 103 gc/L (GII) in environmental waters. For HAdV the averages were: 9.8 x 104 (treated wastewater); 9.8 x 106 gc/L (environmental waters) and 9.1 x 104 (oyster farm South) e 1.5 x 105 gc/g (oyster farm North). The surveillance results have shown a higher prevalence of HAdV in the aquatic environment, followed by NoV, RV-A and HAV. In the study of HAdV infectivity decay in water under different temperatures, results showed a significant inactivation only after 23 weeks at 19°C for both HAdV tested. These results have shown a long-term survival of adenoviruses in environmental waters

Cytotoxicity and antiviral activity evaluation of Cymbopogon spp hydroethanolic extracts

Cymbopogon citratus and C. nardus are noteworthy among the several existing plant species displaying medicinal properties, due to the potential pharmacological activity of these species, including antiviral, antibacterial, antifungal and anti-trypanosomal activities. The objective of this study was to carry out in vitro toxicity tests of plant extracts from both species and analyze potential antiviral activity against Human mastadenovirus serotype 5 (HAdV-5). Two cell lines (A549 and VERO) were used and mitochondrial and lysosomal viability were determined by the MTT and neutral red assay, respectively, after two exposure times (24 hours and six days). The aim of these assays was to counteract the behavior of the extracts against the different cell lines and determine their non-toxic concentration range, in order to evaluate possible antiviral activity against HAdV-5. Plaque reduction and inhibition index of viral titer assays were performed using the maximum non-cytotoxic concentrations (MNCC) of each extract. The results indicate MNCC at 625 μg/mL for all extracts, except for Cymbopogon nardus obtained with 80% ethanol (CN80), which showed toxicity at concentrations higher than 312.5 μg/mL. CN80 was the only extract that displayed potential activity against HAdV-5, at a concentration of 75 μg/mL, becoming a candidate for extract fraction purification and/or the isolation of substances related to the observed antiviral activity

Low occurrence of Hepatitis A virus in water samples from an urban area of Southern Brazil

Hepatitis A virus (HAV), a member of Picornaviridae family, is the main causative agent of acute viral hepatitis in the world, mainly in developing countries. HAV may be present in contaminated water and food and its presence is often associated to a lesser extent with socioeconomic factors and environmental quality. The main goals in the present study were to standardize a cell culture combined to a polymerase chain reaction protocol for the detection and quantification of viral viability and analyze whether the virus could be found in water samples collected in four urban streams of Sinos River watershed. Virus recovery was assayed from known virus concentrations measured in experimentally contaminated raw and ultrapure water (MilliQ®). Recovery rates ranged from 270% in raw water to 15,000% in ultrapure water. In a second step, a qPCR coupled to a previous passage in cells, demonstrated more analytical sensitivity when compared to samples assayed without a previous passage in cell cultures. HAV genome was detected in only 1 of 84 samples analyzed, pointing to a very low occurrence of HAV in water samples in the studied region. These findings are remarkable, since no more than 5% of the domestic sewage in this area is treated pointing to a low occurrence of HAV in the population living nearby during the study period

Evaluation and molecular characterization of human adenovirus in drinking water supplies: viral integrity and viability assays

BACKGROUND: Human adenoviruses (HAdVs) are the second-leading cause of childhood gastroenteritis worldwide. This virus is commonly found in environmental waters and is very resistant to water disinfection and environmental stressors, especially UV light inactivation. Molecular techniques, such as PCR-based methods (Polymerase Chain Reaction), are commonly used to detect and identify viral contamination in water, although PCR alone does not allow the discrimination between infectious and non-infectious viral particles. A combination of cell culture and PCR has allowed detection of infectious viruses that grow slowly or fail to produce cytopathic effects (CPE) in cell culture. This study aimed to assess the integrity and viability of human adenovirus (HAdV) in environmental water and evaluate circulating strains by molecular characterization in three sites of the water supply in Florianópolis, Santa Catarina Island, Brazil: Peri Lagoon water, spring source water, and water from the public water supply system. METHODS: Water samples were collected, concentrated and HAdV quantified by real-time PCR. Viral integrity was evaluated by enzymatic assay (DNase I) and infectivity by plaque assay (PA) and integrated cell culture using transcribed mRNA (ICC-RT-qPCR). Samples containing particles of infectious HAdV were selected for sequencing and molecular characterization. RESULTS: The analyzed sites contained 83, 66 and 58% undamaged HAdV particles (defined as those in which the genetic material is protected by the viral capsid) at Peri Lagoon, spring source water and public supply system water, respectively. Of these, 66% of the particles (by PA) and 75% (by ICC-RT-qPCR) HAdV were shown to be infectious, due to being undamaged in Peri Lagoon, 33% (by PA) and 58% (by ICC-RT-qPCR) in spring source water and 8% (by PA) and 25% (by ICC-RT-qPCR) in the public water supply system. ICC-RT-qPCR, a very sensitive and rapid technique, was able to detect as low as 1 × 10(2) HAdV genome copies per milliliter of infectious viral particles in the environmental water samples. The molecular characterization studies indicated that HAdV-2 was the prevalent serotype. CONCLUSIONS: These results indicate a lack of proper public health measures. We suggest that HAdV can be efficiently used as a marker of environmental and drinking water contamination and ICC-RT-qPCR demonstrated greater sensitivity and speed of detection of infectious viral particles compared to PA

Effects of Lipophilicity and Structural Features on the Antiherpes Activity of Digitalis Cardenolides and Derivatives

Abstract There is growing interest in exploring Digitalis cardenolides as potential antiviral agents. Hence, we herein investigated the influence of structural features and lipophilicity on the antiherpes activity of 65 natural and semisynthetic cardenolides assayed in vitro against HSV‐1. The presence of an α,β‐unsaturated lactone ring at C‐17, a β‐hydroxy group at C‐14 and C‐3β‐OR substituents were considered essential requirements for this biological activity. Glycosides were more active than their genins, especially monoglycosides containing a rhamnose residue. The activity enhanced in derivatives bearing an aldehyde group at C‐19 instead of a methyl group, whereas inserting a C‐5β‐OH improved the antiherpes effect significantly. The cardenolides lipophilicity was accessed by measuring experimentally their log P values (n‐octanol‐water partition coefficient) and disclosed a range of lipophilicity (log P 0.75±0.25) associated with the optimal antiherpes activity. In silico studies were carried out and resulted in the establishment of two predictive models potentially useful to identify and/or optimize novel antiherpes cardenolides. The effectiveness of the models was confirmed by retrospective analysis of the studied compounds. This is the first SAR study addressing the antiherpes activity of cardenolides. The developed computational models were able to predict the active cardenolides and their log P values

Low occurrence of Hepatitis A virus in water samples from an urban area of Southern Brazil

ABSTRACT Hepatitis A virus (HAV), a member of Picornaviridae family, is the main causative agent of acute viral hepatitis in the world, mainly in developing countries. HAV may be present in contaminated water and food and its presence is often associated to a lesser extent with socioeconomic factors and environmental quality. The main goals in the present study were to standardize a cell culture combined to a polymerase chain reaction protocol for the detection and quantification of viral viability and analyze whether the virus could be found in water samples collected in four urban streams of Sinos River watershed. Virus recovery was assayed from known virus concentrations measured in experimentally contaminated raw and ultrapure water (MilliQ®). Recovery rates ranged from 270% in raw water to 15,000% in ultrapure water. In a second step, a qPCR coupled to a previous passage in cells, demonstrated more analytical sensitivity when compared to samples assayed without a previous passage in cell cultures. HAV genome was detected in only 1 of 84 samples analyzed, pointing to a very low occurrence of HAV in water samples in the studied region. These findings are remarkable, since no more than 5% of the domestic sewage in this area is treated pointing to a low occurrence of HAV in the population living nearby during the study period