RESUMO
Research on innovative mucosal adjuvants is essential to develop new vaccines for safe mucosal application. In this work, we propose the development of a Lactococcus lactis that expresses a variant of flagellin on its surface (FliC131*), to increase the adjuvanticity of the living cell and cell wall-derived particles (CWDP). We optimized the expression of FliC131*, and confirmed its identity and localization by Western blot and flow cytometry. We also generated CWDP containing FliC131* (CDWP-FliC131*) and evaluated their storage stability. Lastly, we measured the human TLR5 stimulating activity in vitro and assessed the adjuvanticity in vivo using ovalbumin (OVA) as a model antigen. As a result, we generated L. lactis/pCWA-FliC131*, that expresses and displays FliC131* on its surface, obtained the corresponding CWDP-FliC131*, and showed that both activated hTLR5 in vitro in a dose-dependent manner. Furthermore, CWDP-FliC131* retained this biological activity after being lyophilized and stored for a year. Finally, intranasal immunization of mice with OVA plus live L. lactis/pCWA-FliC131* or CWDP-FliC131* induced OVA-specific IgG and IgA in serum, intestinal lavages, and bronchoalveolar lavages. Our work demonstrates the potential of this recombinant L. lactis with an enhanced adjuvant effect, prompting its further evaluation for the design of novel mucosal vaccines.
Assuntos
Adjuvantes Imunológicos , Flagelina , Lactococcus lactis , Camundongos Endogâmicos BALB C , Ovalbumina , Receptor 5 Toll-Like , Lactococcus lactis/imunologia , Animais , Flagelina/imunologia , Flagelina/administração & dosagem , Camundongos , Humanos , Ovalbumina/imunologia , Ovalbumina/administração & dosagem , Receptor 5 Toll-Like/imunologia , Adjuvantes Imunológicos/administração & dosagem , Feminino , Imunidade nas Mucosas/efeitos dos fármacos , Imunidade nas Mucosas/imunologia , Imunização/métodos , Administração IntranasalRESUMO
[RESUMEN]. Hacia 2022, más de 100 países habían introducido una de las cuatro vacunas autorizadas para uso mundial contra rotavirus, sin embargo, según modelos matemáticos se estima que es poco probable que la reducción en mortalidad con vacunas orales supere el 40%. Esto se debe a que la mayoría de las muertes asociadas a RVA ocurren en países de ingresos bajos y medianos, donde la efectividad de estas vacunas es menor. Este problema de desempeño en medios de bajo nivel socio-económico, se verifica también en menor efectividad sobre morbilidad y duración de la protección. En este trabajo se discuten los posible factores involucrados en este bajo rendimiento relacionados al patógeno, el huésped y factores ambientales. En Argentina, la vacuna monovalente Rotarix® (GSK) ha sido incorporada en el Calendario Nacional en 2015, sin embargo, aún no existen estudios completos de efectividad. Las observaciones iniciales de nuestro grupo registran una disminución en el número de casos de gastroenteritis aguda requi- riendo hospitalización en el Hospital de Niños Ricardo Gutiérrez (HNRG) a partir del 2015. Para los casos con diagnóstico específico de RVA la diferencia fue cada vez más significativa para los años 2016, 2017 y 2018 (p<<0,05). Comparando las medias anuales en los períodos pre y post vacunales se hallan valores de 104,7 para los años 2008-2014 y de 40,2 para los años 2015-2018 (p<0,05) lo que implica una disminución del 61,6%. También se hallaron diferencias a la baja en el número medio de internaciones por GEA por todas las causas del 19,6%.
[ABSTRACT]. By 2022, more than 100 countries had introduced one of the four vaccines authorized for global use against rotavirus; however, according to mathematical models, it is estimated that the reduction in mortality with oral vaccines is unlikely to exceed 40%. This is because the majority of RVA-associated deaths occur in low- and middle-income countries, where the effectiveness of these vaccines is lower. This performance problem in low socioeconomic environments is also verified in lower effectiveness on morbidity and duration of protection. In this work, the possible factors involved in this low performance related to the pathogen, the host and environmental factors are discussed. In Argentina, the monovalent Rotarix® (GSK) vaccine has been incorporated into the National Schedule in 2015, however, there are still no complete effectiveness studies. The initial observations of our group record a decrease in the number of cases of acute gastroenteritis requiring hospitalization at the Ricardo Gutiérrez Children's Hospital (HNRG) starting in 2015. For cases with a specific diagnosis of RVA, the difference was increasingly significant for the years 2016, 2017 and 2018 (p<<0.05). Comparing the annual averages in the pre- and post-vac- cine periods, values of 104.7 are found for the years 2008-2014 and 40.2 for the years 2015-2018 (p<0.05), which implies a decrease of 61. 6%. Downward differences were also found in the average number of hospitalizations for AGE due to all causes of 19.6%.
Assuntos
Infecções por Rotavirus , Rotavirus , Vacinas contra Rotavirus , Eficácia de Vacinas , Vulnerabilidade SocialRESUMO
Group A rotaviruses (RVA) are the most frequent etiological agents causing severe diarrhea in infants and surveillance of genotype, and genetic characteristics of circulating strains are necessary in order to evaluate vaccine programs. The objectives of this work were to describe G and P genotype from 2012 through 2014 in Buenos Aires, Argentina completing an overview of 19 years of genotype surveillance in our region and to characterize an emerging G1P[8] strain associated with severe cases and five fatalities in 2014. We performed genotyping by RT-PCR. The sequencing of several genes, phylogenetic analyses, and comparative epidemiological data were used to know the origin and phylogenetic relationships of the emerging G1P[8] strain. Along with this report, 19 years of continuous RVA genotype surveillance in Argentina in the pre-vaccine era was covered. During the last year of this surveillance, 2014, a significantly increased incidence of RVA associated gastroenteritis was related to the reemergence of G1P[8] strains, being these ones detected in low frequency in the last nine years. Interestingly, the patients affected were significantly older when compared with those from the last six seasons. Additionally, phylogenetic analysis of several genes infer that these G1P[8] strains were closely related to Asian strains circulating during 2012 and 2013. In addition to this, the suggested extra continental origin for the 2014 G1P[8] strains and the very low circulation of G1 type during nine years probably explain the increased incidence and severity in the gastroenteritis cases and the particular epidemiologic characteristics. In conclusion, this work gives us a whole panorama of the pre-vaccine era of the RVA molecular epidemiology in the most populated region of Argentina. In this way, this work inspires us to continue with this type of studies in the post-vaccination era.
Assuntos
Doenças Transmissíveis Emergentes/epidemiologia , Doenças Transmissíveis Emergentes/virologia , Infecções por Rotavirus/epidemiologia , Infecções por Rotavirus/virologia , Rotavirus/classificação , Argentina/epidemiologia , Proteínas do Capsídeo/genética , Doenças Transmissíveis Emergentes/história , Genoma Viral , Genótipo , História do Século XXI , Humanos , Incidência , Epidemiologia Molecular , Filogenia , Prevalência , Vigilância em Saúde Pública , RNA Viral , Rotavirus/imunologia , Infecções por Rotavirus/história , Infecções por Rotavirus/prevenção & controle , Vacinas contra RotavirusRESUMO
St. Louis encephalitis virus (SLEV) is a mosquito-borne re-emerging flavivirus in Argentina. It is currently necessary to develop specific serological tests that can efficiently discriminate the flaviviruses that circulate in our country. The immunoassays to diagnose SLEV lack specificity because they are based on the detection of structural viral proteins and the human immunoglobulins produced during infection against these proteins cross-react with other flaviviruses. Here, we describe an enzyme-immunoassay designed to detect human IgG antibodies specific to the viral non-structural protein NS5. The results indicate that NS5 is a promising antigen useful to discriminate SLEV from other circulating flaviviruses.
Assuntos
Vírus da Encefalite de St. Louis/imunologia , Encefalite de St. Louis/diagnóstico , Testes Sorológicos , Proteínas não Estruturais Virais/imunologia , Argentina , Reações Cruzadas , Flavivirus/imunologia , HumanosRESUMO
Saint Louis encephalitis virus (SLEV) and West Nile virus (WNV) are two of the major causes of arboviral encephalitis in the Americas. The co-circulation of related flaviviruses in the Americas and prior vaccination against flaviviruses pose problems to the diagnostic specificity of serological assays due to the development of cross-reactive antibodies. An accurate diagnosis method capable of differentiating these related viruses is needed. NS1 is a glycosylated, nonstructural protein, of about 46â¯kDa which has a highly conserved structure. Anti-NS1 antibodies can be detected within 4-8 days after the initial exposure and NS1 is the least cross-reactive of the flaviviral antigens. This study was aimed to generate SLEV and WNV NS1 recombinants proteins for the development of a flavivirus diagnostic test. Local Argentinian isolates were used as the source of NS1 gene cloning, expression, and purification. The protein was expressed in Escherichia coli as inclusion bodies and further purified by metal-chelating affinity chromatography (IMAC) under denaturing conditions. Human sera from SLEV and WNV positive cases showed reactivity to the recombinant NS1 proteins by western blot. The unfolded NS1 proteins were also used as immunogens. The polyclonal antibodies elicited in immunized mice recognized the two recombinant proteins with differential reactivity.
Assuntos
Anticorpos Antivirais/biossíntese , Antígenos Virais/imunologia , Vírus da Encefalite de St. Louis/imunologia , Encefalite de St. Louis/diagnóstico , Proteínas não Estruturais Virais/imunologia , Febre do Nilo Ocidental/diagnóstico , Vírus do Nilo Ocidental/imunologia , Animais , Especificidade de Anticorpos , Antígenos Virais/biossíntese , Antígenos Virais/genética , Argentina , Western Blotting , Cromatografia de Afinidade , Clonagem Molecular , Reações Cruzadas , Diagnóstico Diferencial , Vírus da Encefalite de St. Louis/química , Vírus da Encefalite de St. Louis/genética , Encefalite de St. Louis/imunologia , Encefalite de St. Louis/virologia , Escherichia coli/genética , Escherichia coli/metabolismo , Expressão Gênica , Vetores Genéticos/química , Vetores Genéticos/metabolismo , Humanos , Corpos de Inclusão/química , Camundongos , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/genética , Proteínas Recombinantes/imunologia , Solubilidade , Proteínas não Estruturais Virais/biossíntese , Proteínas não Estruturais Virais/genética , Febre do Nilo Ocidental/imunologia , Febre do Nilo Ocidental/virologia , Vírus do Nilo Ocidental/química , Vírus do Nilo Ocidental/genéticaRESUMO
Rotaviruses are the primary cause of acute gastroenteritis in children worldwide. Although the implementation of live attenuated vaccines has reduced the number of rotavirus-associated deaths, variance in their effectiveness has been reported in different countries. This fact, among other concerns, leads to continuous efforts for the development of new generation of vaccines against rotavirus.In this work, we describe the obtention of cell wall-derived particles from a recombinant Lactococcus lactis expressing a cell wall-anchored version of the rotavirus VP6 protein. After confirming by SDS-PAGE, Western blot, flow cytometry and electronic immunomicroscopy that these particles were carrying the VP6 protein, their immunogenic potential was evaluated in adult BALB/c mice. For that, mucosal immunizations (oral or intranasal), with or without the dmLT [(double mutant Escherichia coli heat labile toxin LT(R192G/L211A)] adjuvant were performed. The results showed that these cell wall-derived particles were able to generate anti-rotavirus IgG and IgA antibodies only when administered intranasally, whether the adjuvant was present or not. However, the presence of dmLT was necessary to confer protection against rotavirus infection, which was evidenced by a 79.5 percent viral shedding reduction.In summary, this work describes the production of cell wall-derived particles which were able to induce a protective immune response after intranasal immunization. Further studies are needed to characterize the immune response elicited by these particles as well as to determine their potential as an alternative to the use of live L. lactis for mucosal antigen delivery.
Assuntos
Antígenos Virais/imunologia , Proteínas do Capsídeo/imunologia , Parede Celular/metabolismo , Portadores de Fármacos/metabolismo , Lactococcus lactis/citologia , Mucosa/metabolismo , Infecções por Rotavirus/prevenção & controle , Rotavirus/fisiologia , Animais , Especificidade de Anticorpos , Antígenos Virais/metabolismo , Proteínas do Capsídeo/metabolismo , Modelos Animais de Doenças , Imunoglobulina A/imunologia , Imunoglobulina G/imunologia , Masculino , Camundongos , Camundongos Endogâmicos BALB CRESUMO
Group C Rotavirus (RVC) has been associated globally with sporadic outbreaks of gastroenteritis in children and adults. RVC also infects animals, and interspecies transmission has been reported as well as its zoonotic potential. Considering its genetic diversity and the absence of effective vaccines, it is important and necessary to develop new generation vaccines against RVC for both humans and animals. The aim of the present study was to develop and characterize an HSV-1-based amplicon vector expressing a human RVC-VP6 protein and evaluate the humoral immune response induced after immunizing BALB/c mice. Local fecal samples positive for RVC were used for isolation and sequencing of the vp6 gene, which phylogenetically belongs to the I2 genotype. We show here that cells infected with the HSV[VP6C] amplicon vector efficiently express the VP6 protein, and induced specific anti-RVC antibodies in mice immunized with HSV[VP6C], in a prime-boost schedule. This work highlights that amplicon vectors are an attractive platform for the generation of safe genetic immunogens against RVC, without the addition of external adjuvants.
Assuntos
Antígenos Virais/genética , Antígenos Virais/imunologia , Proteínas do Capsídeo/genética , Proteínas do Capsídeo/imunologia , Expressão Gênica , Vetores Genéticos/genética , Herpesvirus Humano 1/genética , Rotavirus/genética , Rotavirus/imunologia , Animais , Anticorpos Antivirais/imunologia , Chlorocebus aethiops , Humanos , Imunidade Humoral , Masculino , Camundongos , Filogenia , Proteínas Recombinantes , Células VeroRESUMO
BACKGROUND: Group A rotaviruses (RVA) are the most frequent single etiological agents of severe diarrhea in infants. Since 2006 RVA vaccines have been introduced in national schedules of middle and high income countries with substantial declines in rotavirus associated disease burden. However, surveillance must be maintained to, eventually, detect emerging types or variants selected by the new pressure imposed by vaccination. OBJECTIVES: To analyze the molecular epidemiology of group A rotavirus after vaccine introduction in the region in the context of data from more than 15 years of continuous surveillance in Buenos Aires. STUDY DESIGN: RVA positive diarrhea samples collected in Buenos Aires from 2008 to 2011 were genotyped by RT-PCR. Selected samples were sequenced to gain insight on evolution of common and globally emerging human RVA strains. RESULTS: Lineage III G12P[8] strain emerged in 2008 in Buenos Aires and shared co-dominancy with G3 strains during 2009. An atypical long lasting circulation of G2P[4] strains since 2004 reached rates around 80% in 2011 in Buenos Aires. Sequencing of the VP7 and VP4 genes of representative G2P[4] isolates suggests Brazil as the origin of the 2010-2011 strains. CONCLUSIONS: Globally emergent G12 lineage III strains could be established as dominant strains in a very populated area in two years since emergence. In this work it was also shown that the persistence of G2P[4] strains during 8 years could be related to massive immunization with the monovalent vaccine in the region.
Assuntos
Infecções por Rotavirus/epidemiologia , Infecções por Rotavirus/prevenção & controle , Vacinas contra Rotavirus/imunologia , Rotavirus/isolamento & purificação , Brasil/epidemiologia , Proteínas do Capsídeo/genética , Fezes/virologia , Genótipo , História do Século XXI , Humanos , Vacinação em Massa , Dados de Sequência Molecular , Filogenia , Vigilância em Saúde Pública , RNA Viral/genética , Rotavirus/classificação , Rotavirus/genética , Infecções por Rotavirus/história , Infecções por Rotavirus/virologiaRESUMO
BACKGROUND: Arenavirus matrix protein Z plays an important role in virus budding and is able to generate enveloped virus-like-particles (VLPs) in absence of any other viral proteins. In these VLPs, Z protein is associated to the plasma membrane inner surface by its myristoyl residue. Budding induction and vesicle formation properties can be exploited to generate enveloped VLPs platform. These structures can be designed to carry specific antigen in the inner side or on the surface of VLPs.Vaccines based on VLPs are a highly effective type of subunit vaccines that mimic the overall structure of virus particles in absence of viral nucleic acid, being noninfectious.In this work we assayed the capacity of Junin Z protein to produce VLPs carrying the green fluorescent protein (eGFP), as a model antigen. RESULTS: In this report the Junin Z protein ability to produce VLPs from 293T cells and its capacity to deliver a specific antigen (eGFP) fused to Z was evaluated. Confocal microscopy showed a particular membrane bending in cells expressing Z and a spot welded distribution in the cytoplasm. VLPs were detected by TEM (transmission electron microscopy) and were purified from cell supernatant. The proteinase protection assay demonstrated the VLPs integrity and the absence of degradation of the fused antigen, thus indicating its internal localization. Finally, immunization of mice with purified VLPs produced high titres of anti-eGFP antibodies compared to the controls. CONCLUSIONS: It was proved that VLPs can be generated from cells transfected with a fusion Junin virus Z-eGFP protein in absence of any other viral protein, and the capacity of Z protein to support fusions at the C-terminal, without impairing its budding activity, allowing vehiculization of specific antigens into VLPs.
Assuntos
Antígenos/metabolismo , Vírus Junin/metabolismo , Proteínas Virais/metabolismo , Vírion/metabolismo , Animais , Antígenos/genética , Antígenos/imunologia , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Células HEK293 , Humanos , Camundongos , Microscopia Eletrônica de Transmissão , Microscopia de Fluorescência , Proteínas Recombinantes de Fusão/biossíntese , Proteínas Recombinantes de Fusão/genética , Transfecção , Proteínas Virais/genética , Proteínas Virais/imunologia , Vírion/imunologia , Vírion/ultraestruturaRESUMO
The role of group C rotaviruses as a cause of diarrhea was examined among children <17 years of age admitted to a Hospital in a suburban area of Buenos Aires, Argentina between 1997 and 2003. A total of 1,579 fecal samples were screened for group A (RVA) and C (RVC) rotaviruses by two in-house ELISA methods at Quilmes University (UNQ-ELISA). Samples positive, doubtful and negative by RVC specific UNQ-ELISA (n = 246) were examined further for RVC by another in-house ELISA (CDC-ELISA), electron microscopy, RT-PCR, nested PCR, and Southern hybridization. Sensitivity, specificity, and predictive values for each test were determined. While the sensitivity was comparable for the nested PCR and CDC-ELISA methods (82.5%), the molecular methods were slightly more specific. Poorly preserved particles were often seen in fecal samples, suggesting that degradation of RNA could be a factor influencing the performance of molecular methods. The incidence of RVC was estimated to be 3% without apparent differences among seasons. RVC infected patients had a significantly (P < 0.001) higher median age (6 years vs. 1 year) than those with RVA infection. Sequence of the RVC VP7 gene from six Argentinean strains and sequences reported previously in different countries showed high nucleotide (94.4-99.9%) sequence identities, indicating a high degree of conservation for human RVC VP7 genes among strains collected on five continents over a period of 17 years. These findings indicate that RVC is a significant cause of diarrhea and it is necessary to develop simple and sensitive serological methods for its detection.
Assuntos
Diarreia/virologia , Infecções por Rotavirus/diagnóstico , Rotavirus/classificação , Rotavirus/isolamento & purificação , Adolescente , Antígenos Virais/análise , Argentina , Southern Blotting/métodos , Criança , Pré-Escolar , Sequência Conservada , Ensaio de Imunoadsorção Enzimática/métodos , Fezes/virologia , Hospitais , Humanos , Lactente , Recém-Nascido , Dados de Sequência Molecular , Reação em Cadeia da Polimerase/métodos , Valor Preditivo dos Testes , RNA Viral/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa/métodos , Rotavirus/genética , Rotavirus/imunologia , Infecções por Rotavirus/virologia , Sensibilidade e Especificidade , Análise de Sequência de DNA , Homologia de SequênciaRESUMO
A marine bacterial strain, designated strain JUB59(T), was isolated from surface seawater in Antarctica and subsequently characterized. Cells were found to be Gram-negative, non-motile rods forming butyrous, shiny, yellowish orange colonies on marine agar. Growth occurred at 2-28 degrees C (optimally at 22-25 degrees C) but not at 30 degrees C; Na+ ions were required, but 9 % NaCl (w/v) was not tolerated. Phylogenetic analysis, based on comparisons of the complete 16S rRNA gene sequence of the novel isolate with the sequences of closely related strains, showed that strain JUB59(T) belonged to the family Flavobacteriaceae, representing a novel species of the genus Bizionia. The highest levels of sequence similarity were found with respect to Bizionia myxarmorum ADA-4(T) (97.4 %) and Bizionia algoritergicola APA-1(T) (97.1 %). However, the DNA-DNA relatedness of strain JUB59(T) with respect to these two strains was low (15.9-17.3 and 19.3-22.1 %, respectively). The predominant fatty acids of strain JUB59(T) were iso-15 : 1omega10c (18.1 %), iso-15 : 0 (17.3 %), anteiso-15 : 0 (13.9 %), iso-17 : 0 3-OH (9.2 %), 15 : 0 (6.0 %) and iso-16 : 0 3-OH (5.3 %). The main polar lipids were phosphatidylethanolamine, an aminolipid, an amino-positive phospholipid and two unidentified lipids. MK-6 was the major respiratory quinone (>90 %) and the DNA G+C content was 34 mol%. On the basis of the data obtained, strain JUB59(T) represents a novel species of the genus Bizionia, for which the name Bizionia argentinensis sp. nov. is proposed. The type strain is JUB59(T) (=DSM 19628(T)=CCM-A-29 1259(T)).
Assuntos
Flavobacteriaceae/classificação , Flavobacteriaceae/genética , Água do Mar/microbiologia , Regiões Antárticas , Técnicas de Tipagem Bacteriana , Composição de Bases , DNA Bacteriano/genética , Ácidos Graxos/química , Flavobacteriaceae/química , Flavobacteriaceae/isolamento & purificação , Genes Bacterianos , Genes de RNAr , Dados de Sequência Molecular , Fosfolipídeos/química , Filogenia , Quinonas/química , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Cloreto de Sódio , Microbiologia da ÁguaRESUMO
In spite of active measles virus (MV) vaccination strategies, reemergence continues to occur, impairing global eradication programs. The immune status against measles was evaluated in 350 vaccinated healthy Argentine children and teenagers who received a single dose of the MV Schwarz strain Lirugen vaccine (Aventis Pasteur). Sera were assessed for immunoglobulin G (IgG) antibodies by a commercial enzyme immunoassay (EIA) (Enzygnost; Behring), an in-house EIA, and neutralization EIA. Results obtained with these methods showed a marked decline in IgG level with increasing age. At 1 to 4 years of age, 84% of children had IgG antibodies above 200 mIU/ml, conventionally accepted as protective levels, whereas only 32% of older children and teenagers had antibody levels exceeding 200 mIU/ml. Moreover, the MV IgG content in the teenage group was significantly lower than the IgG antibody level of the group of younger children (P < 0.0001). In contrast, screening for IgG antibody levels to inactivated tetanus vaccine showed that, on average, 80% of this population was fully protected and that this high level of protection remained through the teenage years. This study suggests that within this population a considerable proportion of individuals had low measles antibody levels that may be insufficient to protect against reinfections or clinical disease.
Assuntos
Anticorpos Antivirais/sangue , Vacina contra Sarampo/imunologia , Vírus do Sarampo/imunologia , Sarampo/prevenção & controle , Adolescente , Fatores Etários , Anticorpos Antibacterianos/sangue , Argentina , Criança , Pré-Escolar , Feminino , Humanos , Técnicas Imunoenzimáticas , Imunoglobulina G/sangue , Lactente , Masculino , Vacina contra Sarampo/administração & dosagem , Testes de Neutralização , Estatística como Assunto , Toxoide Tetânico/imunologiaRESUMO
A rapid purification method of rotavirus particles to high yield retaining the double shelled structure of infectious virus is described. Group A rotavirus (UK strain) was concentrated through a cushion of colloidal silica (rho=1.10 g/cm(3)) or by precipitating with polyethylene glycol 8000. After concentration, infectious rotavirus was cleared from host cell proteins by density equilibrium centrifugation in gradients of colloidal silica using near vertical rotors. Characterisation of purified virus assessed by electron microscopy and poliacrylamide gel electrophoresis (PAGE) revealed the typical wheel shape structure of rotavirus particles and the presence of the 11 segments of dsRNA arranged in the 4-2-3-2 pattern. Presence of rotavirus structural proteins including VP6, VP4 and VP7 from the outer shell, was demonstrated by SDS-PAGE and Western blot using polyclonal and VP6-specific monoclonal antibodies. This method achieved a approximately 1500 fold purification, which retained approximately 80% infectivity depending on the concentration protocol used, while yielding 160 microg of viral protein per each litre of infected cell culture medium. The time required for the isopycnic centrifugation was only 25 min and the entire completion of the method required 3.5 h. The method is simple technically and applicable to the purification of large as well as minute amounts of virus.
Assuntos
Rotavirus/isolamento & purificação , Animais , Linhagem Celular , Centrifugação com Gradiente de Concentração/métodos , Feminino , Haplorrinos , Coelhos , Rotavirus/imunologia , Rotavirus/fisiologia , Fatores de Tempo , Proteínas Estruturais Virais/análise , VírionRESUMO
The incidence of human group C rotavirus infections among children and adults in Buenos Aires was evaluated by enzyme linked immunosorbent assays (ELISA) based on recombinant group C VP6 protein (Cowden strain). A total of 976 stool samples taken from patients (ages 6 months to 15 years) with acute diarrhea were tested for the presence of group C rotavirus. Among these, only 10 (1.02%) were group C rotavirus positive by enzyme-linked immunosorbent assay (ELISA) confirmed by absorption with group C VP6 antibodies and by RT-PCR for both VP6 and VP7 genes. The average age (5.86 years) was significantly superior to that in group A-infected patients (1.63 years). Previous exposure to this virus was assessed by detecting specific IgG in sera taken from healthy individuals grouped by age. Of 844 sera tested, 425 (50.3%) were group C IgG positive by ELISA, confirmed by Western blot analysis. The rates of IgG positivity for group A and C rotaviruses during the first years of life indicated that infections with group C are frequent in older children (3-5 years), whereas group A infections are prevalent in infants and young children (6-18 months). This study shows that group C rotavirus infections in Argentine children occur later in life than group A and are relatively common in spite of the low detection rate of this virus.