RESUMO
Numerous outbreaks of highly pathogenic avian influenza A strain H5N1 have occurred in Nepal since 2009 despite implementation of a national programme to control the disease through surveillance and culling of infected poultry flocks. The objective of the study was to use cost-benefit analysis to compare the current control programme (CCP) with the possible alternatives of: i) no intervention (i.e., absence of control measures [ACM]) and ii) vaccinating 60% of the national poultry flock twice a year. In terms of the benefit-cost ratio, findings indicate a return of US $1.94 for every dollar spent in the CCP compared with ACM. The net present value of the CCP versus ACM, i.e., the amount of money saved by implementing the CCP rather than ACM, is US $861,507 (the benefits of CCP [prevented losses which would have occurred under ACM] minus the cost of CCP). The vaccination programme yields a return of US $2.32 for every dollar spent when compared with the CCR The net present value of vaccination versus the CCP is approximately US $12 million. Sensitivity analysis indicated thatthe findings were robust to different rates of discounting, whereas results were sensitive to the assumed market loss and the number of birds affected in the outbreaks under the ACM and vaccination options. Overall, the findings of the study indicate that the CCP is economically superior to ACM, but that vaccination could give greater economic returns and may be a better control strategy. Future research should be directed towards evaluating the financial feasibility and social acceptability of the CCP and of vaccination, with an emphasis on evaluating market reaction to the presence of H5N1 infection in the country.
Assuntos
Controle de Doenças Transmissíveis/economia , Controle de Doenças Transmissíveis/legislação & jurisprudência , Análise Custo-Benefício , Influenza Aviária/prevenção & controle , Aves Domésticas , Animais , Controle de Doenças Transmissíveis/métodos , Virus da Influenza A Subtipo H5N1/patogenicidade , Vacinas contra Influenza/economia , Vacinas contra Influenza/imunologia , Influenza Aviária/economia , Influenza Aviária/virologia , Modelos Econômicos , Vigilância da População , VacinaçãoRESUMO
Avian influenza virus (AIV) is a type A virus of the family Orthomyxoviridae. Avian influenza virus infection can cause significant economic losses to the poultry industry, and raises a great public health threat due to potential host jump from animals to humans. To develop more effective intervention strategies to prevent and control AIV infection in poultry, it is essential to elucidate molecular mechanisms of host response to AIV infection in chickens. The objective of this study was to identify genes and signal pathways associated with resistance to AIV infection in 2 genetically distinct highly inbred chicken lines (Fayoumi, relatively resistant to AIV infection, and Leghorn, susceptible to AIV infection). Three-week-old chickens were inoculated with 10(7) EID50 of low pathogenic H5N3 AIV, and lungs and trachea were harvested 4 d postinoculation. Four cDNA libraries (1 library each for infected and noninfected Leghorn, and infected and noninfected Fayoumi) were prepared from the lung samples and sequenced by Illumina Genome Analyzer II, which yielded a total of 116 million, 75-bp single-end reads. Gene expression levels of all annotated chicken genes were analyzed using CLC Genomics Workbench. DESeq was used to identify differentially expressed transcripts between infected and noninfected birds and between genetic lines (false discovery rate < 0.05 and fold-change > 2). Of the expressed transcripts in a total of 17,108 annotated chicken genes in Ensembl database, 82.44 and 81.40% were identified in Leghorn and Fayoumi birds, respectively. The bioinformatics analysis suggests that the hemoglobin family genes, the functional involvements for oxygen transportation and circulation, and cell adhesion molecule signaling pathway play significant roles in disease resistance to AIV infection in chickens. Further investigation of the roles of these candidate genes and signaling pathways in the regulation of host-AIV interaction can lead new directions for the development of antiviral drugs or vaccines in poultry.
Assuntos
Proteínas Aviárias/genética , Galinhas/fisiologia , Resistência à Doença , Influenza Aviária/virologia , Pulmão/virologia , Transdução de Sinais , Animais , Proteínas Aviárias/metabolismo , Galinhas/genética , Vírus da Influenza A/fisiologia , Reação em Cadeia da Polimerase/veterinária , Análise de Sequência de RNA/veterinária , TranscriptomaRESUMO
Avian influenza virus (AIV) is a major respiratory disease of poultry that causes catastrophic losses to the poultry industry. The Mx protein has been shown to confer antiviral responses to influenza viruses in mice. One nonsynonymous substitution (S631N) in the chicken Mx protein is reported to be associated with resistance to AIV infection in vitro. The previous studies suggested controversy over whether this substitution in the Mx protein plays an important antiviral role in AIV infection in the chicken. It would be intriguing to investigate if the substitution is associated with resistance to AIV infection both in ovo and in vivo in chickens. In this study, the embryos and young chicks were generated from the cross of Mx1 heterozygous (S631N) parents with an expected segregating ratio of 1:2:1 in the progeny. A PCR length polymorphism was developed to genotype the Mx1 gene from 119 embryos and 48 chickens. The embryonated chicken eggs were inoculated with 10(6) 50% embryo infectious dose (EID(50)) H5N9 AIV on d 13. Hemagglutinating units in allantoic fluid were determined at 48 h postinoculation. For the in vivo study, twenty-four 1-wk-old broilers were inoculated with 10(6) EID(50) H5N3, and virus titers in lungs were evaluated at d 4 postinoculation. This is the first report revealing no significant association between Mx1 genotypes and low pathogenesis AIV infection both in ovo and in vivo in the chicken. Total RNA samples were isolated from chicken lung tissues in the in vivo study, and the Mx1 mRNA expression assay among 3 genotypes also suggested that only heterozygote birds had significantly greater expression with AIV infection than noninfected birds. A recombination breakpoint within Mx1 gene was also first identified, which has laid a solid foundation for further understanding biological function of the Mx1 gene in chickens. The current study provides valuable information on the effect of the Mx1 gene on the genetic resistance to AIV in chickens, and Mx1 will not be applicable for enhancing genetic resistance to AIV infection in chickens.
Assuntos
Anticorpos Antivirais/genética , Galinhas , Proteínas de Ligação ao GTP/metabolismo , Vírus da Influenza A/imunologia , Influenza Aviária/imunologia , Polimorfismo Genético , Animais , Embrião de Galinha , Proteínas de Ligação ao GTP/genética , Regulação da Expressão Gênica/imunologia , Influenza Aviária/virologiaRESUMO
Spread of avian influenza is associated with movement of infected poultry and poultry products, and, as a result, strict international trade restrictions are in place. In addition, the possibility of transmission of avian influenza virus (AIV) strains to mammalian species by the consumption or handling of infected poultry, although a rare occurrence, is an important trade concern. Traditional methods for poultry product decontamination, such as thermal processing, are effective in inactivating AIV. However, alternative technologies such as electron beam (E-beam) irradiation offer some advantages in maintaining organoleptic properties of fresh poultry products. This study was designed to evaluate the applicability of high-energy (10 MeV) E-beam irradiation to inactivate AIV and reduce virus loads in egg products and poultry meat. Commercially available egg-white and ground turkey meat samples were spiked with the low-pathogenic A/chicken/TX/2002 H5N3 AIV and exposed to varying doses of high-energy E-beam irradiation in increments ranging from 0 kGy to 8 kGy. The viral titres in irradiated samples showed a linear dose-dependent reduction. The dose required to achieve 90% reduction (i.e. the D (10) value) of viable AIV loads was 2.3 kGy in phosphate buffer, 1.6 kGy in egg-white and 2.6 kGy in ground turkey meat samples. The effectiveness of E-beam irradiation to inactivate AIV was similar to the previously reported effectiveness of the E-beam against poliovirus and rotavirus. These results illustrate the potential applicability of high-energy (10 MeV) E-beam irradiation as a poultry product decontamination technology to inactivate AIV.
Assuntos
Elétrons , Contaminação de Alimentos/prevenção & controle , Irradiação de Alimentos/métodos , Vírus da Influenza A/efeitos da radiação , Produtos Avícolas/virologia , Animais , Relação Dose-Resposta à RadiaçãoRESUMO
Proteolytic cleavage of hemagglutinin is required for cell entry by receptor-mediated endocytosis and plays a key role in pathogenicity of the influenza virus. Despite several studies describing relationships between bacterial proteases and influenza A viral activation in mammals, very little is known about the role of the normal bacterial flora of birds on hemagglutinin activation. We examined the indigenous intestinal microflora of 100 mixed-sex, 27-d-old Ross chickens from a commercial poultry facility for protease-secreting bacteria. Protease-secreting bacteria were isolated from 82 of 100 chickens with 50 birds exhibiting 2 or more protease-secreting bacterial species. A total of 20 protease-secreting bacterial species were identified: 17 gram-positive cocci, 2 gram-positive rods, and 1 gram-negative rod. Enterococcus faecalis, Enterococcus gallinarum, and Proteus mirabilis were the most frequently observed protease-secreting bacterial species. The presence of proteolytic bacteria in the intestinal tract of poultry in this study suggests the possibility of yet-to-be-described role(s) in cleavage of hemagglutinin that may alter the pathogenicity of avian influenza viruses.
Assuntos
Galinhas , Trato Gastrointestinal/microbiologia , Vírus da Influenza A/patogenicidade , Influenza Aviária/virologia , Animais , Galinhas/microbiologia , Galinhas/virologia , Feminino , Masculino , Peptídeo Hidrolases/metabolismoRESUMO
Helicoverpa zea reproductive virus (HzRV) is a nonoccluded bacilliform virus that affects both female and male moths of the corn earworm H. zea. In order to study the biology and host range of HzRV, a bioassay was previously developed to detect the presence of this virus in infected insects. A drawback of this bioassay is that it is time consuming and requires more than a month to complete. Here we describe the development of a polymerase chain reaction (PCR) assay for the rapid detection of HzRV in infected corn earworms. The genome of HzRV was digested with PstI and cloned into a plasmid vector. Sequences from two different clones, P4 and P13, were selected for designing two sets of primers. These primers were used for PCR and their sensitivity and specificity in detecting HzRV DNA were examined. Both sets of primers produced the expected amplification product in samples containing HzRV DNA but not in uninfected corn earworm samples, Spodoptera frugiperda (Sf-9) cells, or samples from the Autographa californica nuclear polyhedrosis virus. In addition, the primer pair of the clone P13 was sensitive enough to detect approximately 175 copies of viral DNA. We then used this assay to examine feral populations of H. zea from seven geographical locations in the United States. HzRV was detected primarily in the Mississippi populations and to a lesser extent in Iowa and Georgia, but none in Maryland, Missouri, and Texas populations. This PCR assay provides a highly specific, sensitive, and rapid way of detecting the presence of HzRV and will be useful in further studying the host range, tissue specificity, and incidence of this virus in wild populations of the corn earworm.
RESUMO
Kathmandu, Nepal has been classified as a high-risk area for highly pathogenic avian influenza (HPAI) by the Nepali Government. While ducks have an important role in the transmission of avian influenza viruses (AIV), including HPAI, seroprevalence of antibodies to AIV in domestic ducks of Kathmandu has never been assessed. The objectives of this study were (i) to estimate the prevalence of seroconversion to AIV in domestic ducks in major duck-raising areas of Kathmandu and (ii) to assess the effect of age, sex, presence of swine and the number of ducks on the farm on the carriage of antibodies to AIV in these ducks. From April through July of 2011, a cross-sectional study was conducted and a total of 310 ducks in the major duck-raising areas of Kathmandu were sampled. The estimated prevalence of AIV antibodies was 27.2% [95% confidence interval (CI): 24.6-29.5]. Of 62 enrolled farms, 42% had at least one seropositive duck. Half of the enrolled farms also kept pigs of which 52% had at least one seropositive duck. Bivariate analysis indicated association between ducks' seroconversion to AIV and their age, sex and farm size. However, the final multivariable model, after controlling for clustering of ducks within farms, identified age as the only significant risk factor. Based on this model, ducks older than 1 year of age were more likely to be seropositive compared to ducks <6 months of age [odds ratio = 2.17 (1.07-4.39)]. These results provide baseline information about the AIV seroprevalence in domestic ducks in the major duck-raising areas of Kathmandu and identify a high-risk group that can be targeted in surveillance activities. Future studies should be conducted to differentiate the subtypes of AIV present among domestic ducks in Kathmandu, with particular interest in the presence of HPAI viruses.
Assuntos
Anticorpos Antivirais/sangue , Patos/virologia , Vírus da Influenza A/isolamento & purificação , Influenza Aviária/epidemiologia , Doenças das Aves Domésticas/epidemiologia , Fatores Etários , Animais , Animais Domésticos , Estudos Transversais , Feminino , Vírus da Influenza A/imunologia , Influenza Aviária/virologia , Masculino , Nepal/epidemiologia , Doenças das Aves Domésticas/virologia , Estudos Soroepidemiológicos , Fatores Sexuais , SuínosAssuntos
Herpesvirus Galináceo 2/genética , Proteínas Virais/genética , Genes Reguladores , Glicoproteínas/química , Glicoproteínas/genética , Herpesvirus Galináceo 2/química , Herpesvirus Galináceo 2/enzimologia , Peso Molecular , Fases de Leitura Aberta , Proteínas Virais/química , Proteínas Estruturais Virais/genética , Replicação Viral/genéticaRESUMO
Marek's disease virus (MDV) oncogene meq has been identified as the gene involved in tumorigenesis in chickens. We have recently developed a Meq-null virus, rMd5 Delta Meq, in which the oncogene meq was deleted. Vaccine efficacy experiments conducted in Avian Disease and Oncology Laboratory (ADOL) 15I(5) x 7(1) chickens vaccinated with rMd5 Delta Meq virus or an ADOL preparation of CVI988/Rispens indicated that rMd5 Delta Meq provided superior protection than CVI988/Rispens when challenged with the very virulent plus MDV 648A strain. In the present study we set to investigate the vaccine efficacy of rMd5 Delta Meq in the field compared to several commercial preparations of CVI988/Rispens. Three large-scale field experiments, in which seeder chickens were inoculated with a very virulent plus strain of 686, vv+ MDV, were conducted in a model developed by Hy-Line International. In addition, comparisons were made with bivalent vaccine (HVT+SB-1), HVT alone and several serotype 3 HVT-vectored vaccines individually or in combination with CVI988/Rispens. Experimental results showed that addition of HVT to either of the two commercial CVI988/Rispens preparations tested (A or B) did not enhance protection conferred by CVI988/Rispens alone and that rMd5 Delta Meq was a better or equal vaccine compared to any of the CVI988/Rispens vaccines tested under the conditions of the field trials presented herein. Our results also emphasized the complexity of factors affecting vaccine efficacy and the importance of challenge dose in protection.
Assuntos
Deleção de Genes , Mardivirus/imunologia , Vacinas contra Doença de Marek/imunologia , Doença de Marek/prevenção & controle , Proteínas Oncogênicas Virais , Doenças das Aves Domésticas/prevenção & controle , Animais , Células Cultivadas , Galinhas , Relação Dose-Resposta Imunológica , Patos , Mardivirus/genética , Doença de Marek/genética , Doença de Marek/imunologia , Vacinas contra Doença de Marek/genética , Doenças das Aves Domésticas/genética , Doenças das Aves Domésticas/imunologiaRESUMO
The relative mobility of the 11 dsRNA genomic segments of 19 Aquareovirus isolates from fish and shellfish were compared by polyacrylamide gel electrophoresis. This study revealed distinct variations of electrophoretic profiles (electropherotypes) of many aquareovirus isolates. No correlation was observed between the electropherotype and the species from which the isolates were obtained, but there was correlation with the geographic site of isolation. Using reciprocal RNA-RNA dot blot hybridization under high-, medium-, and low-stringency conditions five different genetic groups (genogroups) could be established (designated A through E). RNA-RNA hybridization showed that segment 10, the genome segment that codes for the major outer capsid protein, was the most variable gene. No genetic relationship was observed between these aquareoviruses and rotaviruses in groups A and C.
Assuntos
Genoma Viral , RNA de Cadeia Dupla/análise , RNA Viral/análise , Reoviridae/genética , Animais , Linhagem Celular , Eletroforese em Gel de Poliacrilamida , Embrião não Mamífero , Feminino , Ictaluridae , Hibridização de Ácido Nucleico , Ovário , RNA de Cadeia Dupla/genética , RNA Viral/genética , Reoviridae/isolamento & purificação , Salmão , VírusRESUMO
Three recombinant avian leukosis subgroup J viruses, ADOL 5701A, ADOL 5701ADelta, and ADOL 6803A, carrying a subgroup A envelope have been isolated and characterized. These viruses were identified by their ability to replicate in DF-1/J, a recombinant chicken embryo fibroblast (CEF) cell line expressing the subgroup J envelope that is resistant to subgroup J replication. Flow cytometric analysis of DF-1/J cells infected with ADOL 5701 and ADOL 6803, two subgroup J isolates, indicated cross-reactivity with subgroup A chicken polyclonal serum. Based on published sequences of subgroups A and J isolates, we designed a series of primers to PCR amplify the envelope and LTR of these viruses. PCR products were obtained when the forward primer was specific for subgroup A gp85 envelope protein gene and the reverse primer was specific for subgroup J LTR. Sequence analysis of the PCR products indicated that these viruses had a subgroup A gp85, a subgroup E gp37, and a subgroup J LTR. Interestingly, these viruses had previously been propagated in CEF from the alv6 chicken line, a line that carries a replication defective recombinant endogenous virus expressing a subgroup A envelope (RAV 0-A(1)). Sequence analysis of RAV 0-A(1) gp85 and gp37 envelope proteins indicated that they were almost identical to those of the recombinants ADOL 5701A and ADOL 6803A. These results indicate that these three recombinant viruses arose by recombination between exogenous subgroup J isolates and a recombinant defective endogenous virus with subgroup A envelope.
Assuntos
Vírus da Leucose Aviária/isolamento & purificação , Animais , Vírus da Leucose Aviária/classificação , Vírus da Leucose Aviária/genética , Sequência de Bases , Linhagem Celular , Embrião de Galinha , Citometria de Fluxo , Dados de Sequência Molecular , Recombinação Genética , Sequências Repetidas TerminaisRESUMO
Genome segment 10 of the coho salmon (CSR) strain of genogroup B aquareovirus has been cloned and sequenced. The gene is at least 936 nucleotides in length and has a major open reading frame encoding a protein of 293 amino acids with a calculated molecular mass of 31.7 kDa. Comparison of nucleotide and deduced amino acid sequences of genome segment 10 of genogroup A and genogroup B strains indicated 55.7 and 36.5% identity at the nucleotide and amino acid level, respectively. Baculovirus expression and serological identification of the genome segment 10 product of the CSR strain indicated that this gene encodes the major outer capsid protein of genogroup B aquareovirus.
Assuntos
Antígenos Virais , Proteínas do Capsídeo , Capsídeo/genética , Genoma Viral , Reoviridae/genética , Análise de Sequência de DNA , Animais , Sequência de Bases , Linhagem Celular , DNA Viral , Dados de Sequência Molecular , SalmãoRESUMO
The protein products of aquareovirus genome segments 10 and 11 were investigated. The genome segment 10 encodes the major outer capsid protein (VP7) of aquareovirus. The VP7 protein has a molecular weight of 35 kDa and was found to be glycosylated. The electrophoretic mobility of VP7 in SDS-PAGE was unaltered when untreated and deglycosylated proteins were compared, indicating the presence of short oligosaccharide chains. Selective binding of lectins with well-defined sugar specificities suggest that most of the short N-linked carbohydrate chains of VP7 contain galactose residues. Genome segment 11 encoded 2 non-structural proteins (NS29 and NS15). Partial protease mapping indicated that the NS29 and NS15 proteins are derived from initiation of protein synthesis at 2 distinct sites.
Assuntos
Antígenos Virais , Bass/virologia , Proteínas do Capsídeo , Reoviridae/classificação , Animais , Capsídeo/biossíntese , Capsídeo/isolamento & purificação , Capsídeo/metabolismo , Linhagem Celular , Embrião não Mamífero , Genoma Viral , Glicosilação , Biossíntese de Proteínas , Processamento de Proteína Pós-Traducional , RNA de Cadeia Dupla/isolamento & purificação , RNA de Cadeia Dupla/metabolismo , RNA Viral/isolamento & purificação , RNA Viral/metabolismo , Reoviridae/genética , Reoviridae/isolamento & purificação , SalmãoRESUMO
Pathogenic Marek's disease viruses (MDVs) have two head-to-tail copies of a 132-bp repeat. As MDV is serially passaged in cell culture, the virus becomes attenuated and the number of copies of the 132-bp repeat increases from 2 to often more than 20 copies. To determine the role of the repeats in attenuation, we used five overlapping cosmid clones that spanned the MDV genome to reconstitute infectious virus (rMd5). By mutating the appropriate cosmids, we generated clones of infectious MDVs that contained zero copies of the 132-bp repeats, rMd5(Delta132); nine copies of the 132-bp repeats, rMd5(9-132); and nine copies of the 132-bp repeats inserted in the reverse orientation, rMd5(rev9-132). After two passages in cell culture, wild-type Md5, rMd5, and rMd5(Delta132) were stable. However, rMd5(9-132) and rMd5(rev9-132) contained a population of viruses that contained from 3 to over 20 copies of the repeats. A major 1.8-kb mRNA, containing two copies of the 132-bp repeat, was present in wild-type Md5 and rMd5 but was not present in rMd5(Delta132), rMd5(9-132), rMd5(rev9-132), or an attenuated MDV. Instead, the RNAs transcribed from the 132-bp repeat region in rMd5(9-132) and rMd5(rev9-132) closely resembled the pattern of RNAs transcribed in attenuated MDVs. When inoculated into susceptible day-old chicks, all viruses produced various lesions. Thus, expansion of the number of copies of 132-bp repeats, which accompanies attenuation, is not sufficient in itself to attenuate pathogenic MDVs.
Assuntos
Genoma Viral , Herpesvirus Galináceo 2/patogenicidade , Doença de Marek/fisiopatologia , Doenças das Aves Domésticas/fisiopatologia , Sequências Repetitivas de Ácido Nucleico/genética , Animais , Galinhas/virologia , DNA Viral/análise , Dosagem de Genes , Regulação Viral da Expressão Gênica , Herpesvirus Galináceo 2/genética , Herpesvirus Galináceo 2/crescimento & desenvolvimento , Doença de Marek/virologia , Doenças das Aves Domésticas/virologia , RNA Viral/análise , Recombinação Genética , VirulênciaRESUMO
Specific interactions between the nucleocapsid protein (N) and the phosphoprotein (P) of bovine respiratory syncytial virus (BRSV) have been investigated using a yeast-based two-hybrid system. Plasmids encoding the yeast GAL4 DNA binding domain fused with the N gene and GAL4 activation domain fused with the P gene were cotransfected into competent yeast cells. The ability of the N and P proteins to interact in vivo was measured by activation of the lacZ reporter gene by the GAL4 transactivation region. Results indicated that the N and P proteins interact very strongly in vivo. When interactions between N and various deletion mutants of the P protein were examined, an internal region (aa 132-168) and the highly acidic C-terminal region (aa 236-241) of the P protein were found to be essential for N-P interaction. In addition, the highly basic N-terminal region (amino acids 1-40) was found to be involved in N-P interaction to a lesser extent.
Assuntos
Capsídeo/metabolismo , Fosfoproteínas/metabolismo , Vírus Sincicial Respiratório Bovino/química , Proteínas do Core Viral/metabolismo , Sítios de Ligação , Capsídeo/química , Fosfoproteínas/química , Fosfoproteínas/genética , Plasmídeos , Relação Estrutura-Atividade , Transfecção , Proteínas do Core Viral/químicaRESUMO
A nucleic acid hybridization assay was developed to rapidly detect small quantities of aquareovirus RNAs in infected cells and organs. Cloned cDNA copies were synthesized from the genomic RNA of the SBR strain of aquareovirus. By using cloned cDNA probes, aquareovirus RNAs were detected in spleen and kidney tissues of experimentally infected fish.
Assuntos
Peixes/microbiologia , RNA Viral/isolamento & purificação , Reoviridae/isolamento & purificação , Animais , Clonagem Molecular , Sondas de DNA , Doenças dos Peixes/diagnóstico , Doenças dos Peixes/microbiologia , Rim/microbiologia , Hibridização de Ácido Nucleico , RNA Viral/genética , Reoviridae/classificação , Reoviridae/genética , Infecções por Reoviridae/diagnóstico , Infecções por Reoviridae/microbiologia , Infecções por Reoviridae/veterinária , Baço/microbiologia , Truta/microbiologiaRESUMO
During a three years survey, a total of 149 samples from 20 farms of rainbow trout, salmon and turbot were examined for the presence of virus with the purpose to study the viral infections affecting cultured fish and their incidence in the fishfarms of Northwestern Spain. Infectious pancreatic necrosis virus (IPNV) was the only viral agent isolated from salmonid fish. Fry and fingerlings of trout showed the highest infection rate (24%). This virus was not detected in broodstock or embryonated eggs, although it was isolated from ovaric and seminal fluids and from juvenile carriers. From 24 samples of salmon analyzed, IPNV was only detected in one sample of juveniles. Examination of turbot led the isolation of a new virus belonging to the reoviridae family, which affected to the ongrowing population. All of the IPNV tested belonged to serotype Sp regardless of the origin of the trout stocks. During the monitorization of imported embryonated eggs, no virus was detected from any of the samples. However, in some case, IPNV was isolated when testing the fry obtained in our laboratory from those samples of imported eggs. Our findings indicate that: i) the analysis of fingerlings increase the probability to detect viral infections allowing us an optimal control of importations, and ii) most of the viral infections of fish take place in the own fish farms. The detection of mixed viral and bacterial infections emphasize the importance of carrying out an integral microbiological analysis to determine the causal agent(s) of fish mortalities.
Assuntos
Doenças dos Peixes/epidemiologia , Viroses/veterinária , Animais , Surtos de Doenças , Ovos , Doenças dos Peixes/microbiologia , Doenças dos Peixes/transmissão , Linguados/crescimento & desenvolvimento , Linguados/microbiologia , Reoviridae/isolamento & purificação , Infecções por Reoviridae/epidemiologia , Infecções por Reoviridae/veterinária , Salmão/crescimento & desenvolvimento , Salmão/microbiologia , Espanha/epidemiologia , Truta/crescimento & desenvolvimento , Truta/microbiologia , Viroses/epidemiologia , Viroses/microbiologia , Viroses/transmissãoRESUMO
The nucleotide and deduced amino acid sequences of genome segment 10 of aquareovirus strain SBR, encoding the major outer capsid protein (VP7), have been determined. Genome segment 10 of SBR virus is 986 nucleotides long and encodes a polypeptide of 298 amino acids with a predicted molecular mass of 32,430 Da. There are 26 non-translated nucleotides at the 5' end and 66 non-translated nucleotides at the 3' end. Using a recombinant baculovirus system, the VP7 protein of SBR virus was expressed to a high level. The baculovirus-produced VP7 protein was similar both in its size and antigenic properties to the authentic aquareovirus VP7 protein. Antiserum from a rabbit immunized with the baculovirus-produced VP7 protein failed to neutralize the homologous aquareovirus strain. As determined by Western blotting, this antiserum reacted with aquareovirus strains belonging to the same genogroup as SBR virus, but did not react with aquareovirus strains belonging to the other genogroups.
Assuntos
Antígenos Virais , Proteínas do Capsídeo , Capsídeo/genética , Reoviridae/genética , Animais , Sequência de Bases , Capsídeo/química , Capsídeo/imunologia , Clonagem Molecular , Genótipo , Dados de Sequência Molecular , Coelhos , SalmãoRESUMO
A comparative analysis of the phenotypic and serological properties of Carnobacterium strains associated with mortalities of cultured striped bass and channel catfish and the properties of isolates from wild brown bullhead catfish in the Chesapeake Bay area in Maryland was conducted. All of the strains were gram-positive, facultatively anaerobic, nonmotile, non-spore-forming rods occurring singly or in short chains. They did not produce cytochrome oxidase or catalase, did not reduce nitrate, failed to produce H2S, were unable to grow on acetate medium, and did not produce gas from glucose or gluconate. The temperature and salinity ranges for most of the strains were 10 to 37 degrees C and 0 to 6% NaCl, respectively. The strains all fermented mannitol and inulin and were arginine dihydrolase positive; these are typical characteristics of Carnobacterium piscicola. The carbohydrate fermentation pattern exhibited by all of the isolates with the API-50 CHL system was also very similar to that shown by C. piscicola. Acid was produced from ribose, glucose, fructose, mannose, mannitol, N-acetylglucosamine, amygdaline, arbutin, esculin, salicin, cellobiose, maltose, sucrose, trehalose, and gentiobiose. The Carnobacterium strains did not show proteolytic, lipolytic, amylolytic, or hemolytic activity. Eighteen drugs were tested; all strains proved to be resistant to chloramphenicol, gentamicin, kanamycin, streptomycin, trimethoprim, quinolones, and nitrofurans. The analysis of membrane proteins supported the phenotypic similarities, two main patterns were established, one shared by the striped bass isolates and the reference strain of C. piscicola and another shared by most of the catfish strains. However, the agglutination assays demonstrated that only one Carnobacterium strain from striped bass was serologically related to C. piscicola ATCC 35586.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Bass/microbiologia , Bacilos Gram-Positivos Asporogênicos/classificação , Ictaluridae/microbiologia , Animais , Doenças dos Peixes/microbiologia , Bacilos Gram-Positivos Asporogênicos/isolamento & purificação , Lactobacillaceae/classificação , Lactobacillaceae/isolamento & purificação , Lactobacillaceae/patogenicidade , Fenótipo , Sorotipagem , Truta/microbiologia , VirulênciaRESUMO
Biochemical characteristics of five rotavirus-like viruses isolated from striped bass (Morone saxatilis), turbot (Scophthalmus maximus), smelt (Osmerus mordax) and Atlantic salmon (Salmo salar) in North America and Europe were compared. The genome of each isolate was composed of 11 segments of dsRNA and each isolate had a unique electropherotype in polyacrylamide gels. Agarose gel electrophoresis showed similar RNA profiles for all four isolates from North America, whereas the RNA profile of the isolate from Europe was different. Analysis of virion proteins revealed that each virus had five structural proteins ranging in Mr from 130,000 to 34,000. Each isolate had a unique polypeptide profile but their overall polypeptide patterns were similar. Reciprocal RNA-RNA blot hybridization demonstrated that all these rotavirus-like viruses cross-hybridized with each other except for the isolate from Europe which did not hybridize with the RNA from any of the other isolates. No genetic relationship was found between these rotavirus-like viruses of fish and a true group A rotavirus (SA11).