RESUMO
Influenza A viruses of the H2 subtype represent a zoonotic and pandemic threat to humans due to a lack of widespread specific immunity. Although A(H2) viruses that circulate in wild bird reservoirs are distinct from the 1957 pandemic A(H2N2) viruses, there is concern that they could impact animal and public health. There is limited information on AIVs in Latin America, and next to nothing about H2 subtypes in Brazil. In the present study, we report the occurrence and genomic sequences of two influenza A viruses isolated from wild-caught white-rumped sandpipers (Calidris fuscicollis). One virus, identified as A(H2N1), was isolated from a bird captured in Restinga de Jurubatiba National Park (PNRJ, Rio de Janeiro), while the other, identified as A(H2N2), was isolated from a bird captured in Lagoa do Peixe National Park (PNLP, Rio Grande do Sul). DNA sequencing and phylogenetic analysis of the obtained sequences revealed that each virus belonged to distinct subtypes. Furthermore, the phylogenetic analysis indicated that the genomic sequence of the A(H2N1) virus isolated from PNRJ was most closely related to other A(H2N1) viruses isolated from North American birds. On the other hand, the A(H2N2) virus genome recovered from the PNLP-captured bird exhibited a more diverse origin, with some sequences closely related to viruses from Iceland and North America, and others showing similarity to virus sequences recovered from birds in South America. Viral genes of diverse origins were identified in one of the viruses, indicating local reassortment. This suggests that the extreme South of Brazil may serve as an environment conducive to reassortment between avian influenza virus lineages from North and South America, potentially contributing to an increase in overall viral diversity.
Assuntos
Charadriiformes , Vírus da Influenza A , Influenza Aviária , Filogenia , Vírus Reordenados , Animais , Brasil , Influenza Aviária/virologia , Influenza Aviária/epidemiologia , Vírus da Influenza A/genética , Vírus da Influenza A/isolamento & purificação , Vírus Reordenados/genética , Vírus Reordenados/isolamento & purificação , Charadriiformes/virologia , Genoma Viral , Aves/virologiaRESUMO
Wild aquatic birds are the natural reservoirs of avian influenza viruses (AIVs). It is estimated that 100 million seabirds live in the Antarctic Peninsula and adjacent islands, regularly encountering migratory birds that use the islands to nest. Between 2010 and 2013, we collected samples from 865 seabirds in Elephant, King George and Livingston islands, around Antarctica Peninsula: chinstrap penguin (n = 143); gentoo penguin (n = 208); Adelie penguin (n = 46); brown skua (n = 90); Cape petrel (n = 115) and southern giant petrel (n = 263). Serum (n = 673) samples were analysed by competitive ELISA and swabs (n = 614) were tested by one step real-time RT-PCR for avian influenza virus (AIV). Sera from 30 chinstrap penguins, 76 brown skuas and a single Adelie penguin were seropositive for AIV. Thirteen swab samples were AIV positive by RT-PCR, and complete genome sequences of H6N8 AIVs isolated from brown skua and chinstrap penguin in 2011 were obtained. Phylogenetic analyses indicated that all gene segments of the H6N8 viruses were closely related to Argentinian and Chilean AIVs. The prevalence with which we identified evidence for AIVs infection in various Antarctic seabirds suggest viral circulation in Antarctic avifauna and interspecies viral transmission in the sub-Antarctic region.
Assuntos
Charadriiformes , Vírus da Influenza A , Influenza Aviária , Spheniscidae , Animais , Regiões Antárticas , Influenza Aviária/epidemiologia , Filogenia , Animais Selvagens , Vírus da Influenza A/genética , ChileRESUMO
BACKGROUND: There is insufficient knowledge about the relation of avian influenza virus (AIV) to migratory birds in South America. Accordingly, we studied samples obtained over a 4-year period (2009-2012) from wild birds at a major wintering site in southern Brazil. METHODS: We obtained 1212 oropharyngeal/cloacal samples from wild birds at Lagoa do Peixe National Park and screened them for influenza A virus by RT-PCR amplification of the matrix gene. Virus isolates were subjected to genomic sequencing and antigenic characterization. RESULTS: Forty-eight samples of 1212 (3.96%) contained detectable influenza virus RNA. Partial viral sequences were obtained from 12 of these samples, showing the presence of H2N2 (1), H6Nx (1), H6N1 (8), H9N2 (1), and H12N5 (1) viruses. As H6 viruses predominated, we generated complete genomes from all 9 H6 viruses. Phylogenetic analyses showed that they were most similar to viruses of South American lineage. The H6N1 viruses caused no disease signs in infected ferrets and, despite genetic differences, were antigenically similar to North American isolates. CONCLUSIONS: Lagoa do Peixe National Park is a source of multiple AIV subtypes, with the levels of influenza virus in birds being highest at the end of their wintering period in this region. H6N1 viruses were the predominant subtype identified. These viruses were more similar to viruses of South American lineage than to those of North American lineage.
Assuntos
Aves/virologia , Variação Genética , Vírus da Influenza A/classificação , Vírus da Influenza A/isolamento & purificação , Influenza Aviária/virologia , Animais , Antígenos Virais/análise , Brasil , Cloaca/virologia , Vírus da Influenza A/genética , Orofaringe/virologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Análise de Sequência de DNA , Proteínas da Matriz Viral/genéticaRESUMO
The occurrence of avian influenza viruses (AIV) has been extensively studied in aquatic birds in the Northern hemisphere; however, much less information is available for the South American region. In 2009-2010, we sampled 1006 wild aquatic birds (90% Charadriiformes, 9% Anseriformes, and 1% other groups) at three locations on the Brazilian Amazon coast, a region that serves as a major stop-over and wintering site along the Atlantic Americas flyway. Real-time RT-PCR identified five samples as positive; however, no AIV isolates could be obtained and Illumina sequencing did not produce gene sequences that would allow further characterization of the virus.
Assuntos
Anseriformes/virologia , Vírus da Influenza A/isolamento & purificação , Influenza Aviária/epidemiologia , Animais , Animais Selvagens , Aves , Brasil/epidemiologiaRESUMO
Migratory aquatic birds play an important role in the maintenance and spread of avian influenza viruses (AIV). Many species of aquatic migratory birds tend to use similar migration routes, also known as flyways, which serve as important circuits for the dissemination of AIV. In recent years there has been extensive surveillance of the virus in aquatic birds in the Northern Hemisphere; however in contrast only a few studies have been attempted to detect AIV in wild birds in South America. There are major flyways connecting South America to Central and North America, whereas avian migration routes between South America and the remaining continents are uncommon. As a result, it has been hypothesized that South American AIV strains would be most closely related to the strains from North America than to those from other regions in the world. We characterized the full genome of three AIV subtype H11N9 isolates obtained from ruddy turnstones (Arenaria interpres) on the Amazon coast of Brazil. For all gene segments, all three strains consistently clustered together within evolutionary lineages of AIV that had been previously described from aquatic birds in North America. In particular, the H11N9 isolates were remarkably closely related to AIV strains from shorebirds sampled at the Delaware Bay region, on the Northeastern coast of the USA, more than 5000 km away from where the isolates were retrieved. Additionally, there was also evidence of genetic similarity to AIV strains from ducks and teals from interior USA and Canada. These findings corroborate that migratory flyways of aquatic birds play an important role in determining the genetic structure of AIV in the Western hemisphere, with a strong epidemiological connectivity between North and South America.
Assuntos
Charadriiformes/virologia , Vírus da Influenza A/genética , Influenza Aviária/virologia , Migração Animal , Animais , Brasil , Canadá , Vírus da Influenza A/isolamento & purificação , Dados de Sequência Molecular , FilogeniaRESUMO
Aquatic birds are the natural reservoir for avian influenza viruses (AIV). Habitats in Brazil provide stopover and wintering sites for water birds that migrate between North and South America. The current study was conducted to elucidate the possibility of the transport of influenza A viruses by birds that migrate annually between the Northern and Southern Hemispheres. In total, 556 orotracheal/cloacal swab samples were collected for influenza A virus screening using real-time RT-PCR (rRT-PCR). The influenza A virus-positive samples were subjected to viral isolation. Four samples were positive for the influenza A matrix gene by rRT-PCR. From these samples, three viruses were isolated, sequenced and characterized. All positive samples originated from a single bird species, the ruddy turnstone (Arenaria interpres), that was caught in the Amazon region at Caeté Bay, Northeast Pará, at Ilha de Canelas. To our knowledge, this is the first isolation of H11N9 in the ruddy turnstone in South America.
Assuntos
Migração Animal , Charadriiformes/virologia , Vírus da Influenza A/isolamento & purificação , Estações do Ano , Animais , Brasil , Vírus da Influenza A/classificação , Filogenia , SimpatriaRESUMO
BACKGROUND: Despite the use of vaccines, low-pathogenic (LP) H5N2 influenza viruses have continued to circulate and evolve in chickens in Mexico since 1993, giving rise to multiple genetic variants. Antigenic drift is partially responsible for the failure to control H5N2 influenza by vaccination; the contribution of maternal antibodies to this problem has received less attention. METHODS: We investigated the effect of different antisera on the efficacy of vaccination and whether booster doses of vaccine can impact immune suppression. RESULTS: While single doses of inactivated oil emulsion vaccine to currently circulating H5N2 influenza viruses provide partial protection from homologous challenge, chickens that receive high-titer homologous antisera intraperitoneally before vaccination showed effects ranging from added protection to immunosuppression. Post-infection antisera were less immunosuppressive than antisera obtained from field-vaccinated chickens. Homologous, post-infection chicken antisera provided initial protection from virus challenge, but reduced the induction of detectable antibody responses. Homologous antisera from field-vaccinated chickens were markedly immunosuppressive, annulling the efficacy of the vaccine and leaving the chickens as susceptible to infection as non-vaccinated birds. Booster doses of vaccine reduced the immunosuppressive effects of the administered sera. CONCLUSION: Vaccine efficacy against LP H5N2 in Mexico can be severely reduced by maternal antibodies. Source-dependent antisera effects offer the possibility of further elucidation of the immunosuppressive components involved.
Assuntos
Imunização Passiva/métodos , Vírus da Influenza A Subtipo H5N2/imunologia , Vacinas contra Influenza/administração & dosagem , Vacinas contra Influenza/imunologia , Influenza Aviária/prevenção & controle , Vacinação/métodos , Animais , Aves , Galinhas , Imunidade Materno-Adquirida , Influenza Aviária/imunologia , México , Falha de TratamentoRESUMO
The antigenic variation of influenza A virus hemagglutinin (HA) and neuraminidase (NA) glycoproteins requires frequent changes in vaccine formulation. The classical method of creating influenza virus seed strains for vaccine production is to generate 6 + 2 reassortants that contain six genes from a high-yield virus, such as A/PR/8/34 (H1N1) and the HA and NA genes of the circulating strains. The techniques currently used are time-consuming because of the selection process required to isolate the reassortant virus. We generated the high-yield virus A/PR/8/34 (H1N1) entirely from eight plasmids. Its growth phenotype in embryonated chicken eggs was equivalent to that of the wild-type virus. By using this DNA-based cotransfection technique, we generated 6 + 2 reassortants that had the antigenic determinants of the influenza virus strains A/New Caledonia/20/99 (H1N1), A/Panama/2007/99 (H3N2), A/teal/HK/W312 (H6N1), and A/quail/HK/G1/97 (H9N2). Our findings demonstrate that the eight-plasmid system allows the rapid and reproducible generation of reassortant influenza A viruses for use in the manufacture of vaccines.
Assuntos
Vetores Genéticos/genética , Vírus da Influenza A/genética , Vacinas contra Influenza/biossíntese , Vírus Reordenados/genética , Animais , Variação Antigênica/genética , Aves/virologia , Linhagem Celular , Embrião de Galinha , China , Tchecoslováquia , DNA Recombinante/genética , Cães , Genes Virais , Vírus da Influenza A/imunologia , Vírus da Influenza A/isolamento & purificação , Vacinas contra Influenza/genética , Vacinas contra Influenza/imunologia , Vacinas contra Influenza/isolamento & purificação , Nova Caledônia , Panamá , Fenótipo , Vírus Reordenados/imunologia , Vírus Reordenados/isolamento & purificação , Reprodutibilidade dos Testes , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transfecção , Cultura de VírusRESUMO
Devido às complicaçöes associadas às lentes intra-oculares de câmara anterior do tipo alça fechada, muito usada nos anos 80, o uso de lente de câmara anterior tem sofrido críticas, ora relacionadas à sua influência sobre a fisiologia do endotélio, ora relacionadas ao comprometimento do seio camerular, levando à progressiva formaçäo de sinéquias anteriores. Essa preocupaçäo se deve ao grande número de artigos publicados relacionando às lentes de alça fechada, a chamada epidemia de ceratopatia bolhosa durante o início dos anos 90. Encontramos porém evidências na literatura disassociando as modernas lentes de câmara anterior de alça aberta de tais complicaçöes. Neste estudo reportamos nossa experiência com implante lentes de câmara anterior de alça aberta em pacientes portadores de ceratopatia bolhosa pseudofácica (explante com substituiçäo) e afácica (implante secundário) em pacientes submetidos a concomitante transplante penetrante de córnea