RESUMO
The IPN virus (IPNV) causes a highly contagious disease that affects farmed salmonids. IPNV isolates have been phylogenetically classified into seven genogroups, of which two are present in Chile, genogroups 1 and 5. This study aimed to compare the transcriptomic response of rainbow trout fry challenged with two Chilean isolates of IPNV, RTTX (genogroup 1), and ALKA (genogroup 5). Tissue samples from challenged individuals and controls were taken at 1, 7, and 20 days post-challenge and analyzed by RNA-Seq. The results revealed that infection with RTTX elicited a greater modulation of the trout transcriptome compared to ALKA infection, generating a greater number of highly differentially expressed genes in relation to the control fish. Gene Ontology enrichment indicated that functions related to the inflammatory and immune responses were modulated in fish challenged with both isolates throughout the trial, but with different regulation patterns. On day 1 post challenge, these functions were activated in those challenged with ALKA, but suppressed in RTTX-challenged fish. These results suggest that rainbow trout exhibit a differential transcriptomic response to infection with the two genetically distinct IPNV isolates, especially at early times post-infection.
Assuntos
Infecções por Birnaviridae/veterinária , Doenças dos Peixes/virologia , Vírus da Necrose Pancreática Infecciosa , Oncorhynchus mykiss , Transcriptoma , Animais , Infecções por Birnaviridae/genética , Infecções por Birnaviridae/virologia , Doenças dos Peixes/genética , Regulação da Expressão Gênica , Ontologia Genética , Genótipo , Oncorhynchus mykiss/genética , Oncorhynchus mykiss/virologia , RNA-SeqRESUMO
Infectious pancreatic necrosis (IPN) is a viral disease with considerable negative impact on the rainbow trout (Oncorhynchus mykiss) aquaculture industry. The aim of the present work was to detect genomic regions that explain resistance to infectious pancreatic necrosis virus (IPNV) in rainbow trout. A total of 2,278 fish from 58 full-sib families were challenged with IPNV and 768 individuals were genotyped (488 resistant and 280 susceptible), using a 57K SNP panel Axiom, Affymetrix. A genome-wide association study (GWAS) was performed using the phenotypes time to death (TD) and binary survival (BS), along with the genotypes of the challenged fish using a Bayesian model (Bayes C). Heritabilities for resistance to IPNV estimated using genomic information, were 0.53 and 0.82 for TD and BS, respectively. The Bayesian GWAS detected a SNP located on chromosome 5 explaining 19% of the genetic variance for TD. The proximity of Sentrin-specific protease 5 (SENP5) to this SNP makes it a candidate gene for resistance against IPNV. In case of BS, a SNP located on chromosome 23 was detected explaining 9% of the genetic variance. However, the moderate-low proportion of variance explained by the detected marker leads to the conclusion that the incorporation of all genomic information, through genomic selection, would be the most appropriate approach to accelerate genetic progress for the improvement of resistance against IPNV in rainbow trout.
Assuntos
Resistência à Doença/genética , Doenças dos Peixes/virologia , Proteínas de Peixes/genética , Vírus da Necrose Pancreática Infecciosa/fisiologia , Oncorhynchus mykiss/genética , Animais , Teorema de Bayes , Infecções por Birnaviridae/genética , Infecções por Birnaviridae/imunologia , Infecções por Birnaviridae/mortalidade , Infecções por Birnaviridae/veterinária , Doenças dos Peixes/imunologia , Doenças dos Peixes/mortalidade , Proteínas de Peixes/imunologia , Estudo de Associação Genômica Ampla , Interações Hospedeiro-Patógeno/genética , Vírus da Necrose Pancreática Infecciosa/patogenicidade , Oncorhynchus mykiss/imunologia , Oncorhynchus mykiss/virologia , Polimorfismo de Nucleotídeo Único , Replicação Viral/fisiologiaRESUMO
Infectious bursal disease virus (IBDV) is one of the most concerning health problems for world poultry production. IBDVs comprise four well-defined evolutionary lineages known as classic (c), classic attenuated (ca), variant (va) and very virulent (vv) strains. Here, we characterized IBDVs from South America by the genetic analysis of both segments of the viral genome. Viruses belonging to c, ca and vv strains were unambiguously classified by the presence of molecular markers and phylogenetic analysis of the hypervariable region of the vp2 gene. Notably, the majority of the characterized viruses (9 out of 15) could not be accurately assigned to any of the previously described strains and were then denoted as distinct (d) IBDVs. These dIBDVs constitute an independent evolutionary lineage that also comprises field IBDVs from America, Europe and Asia. The hypervariable VP2 sequence of dIBDVs has a unique and conserved molecular signature (272T, 289P, 290I and 296F) that is a diagnostic character for classification. A discriminant analysis of principal components (DAPC) also identified the dIBDVs as a cluster of genetically related viruses separated from the typical strains. DAPC and genetic distance estimation indicated that the dIBDVs are one of the most genetically divergent IBDV lineages. The vp1 gene of the dIBDVs has non-vvIBDV markers and unique nucleotide and amino acid features that support their divergence in both genomic segments. The present study suggests that the dIBDVs comprise a neglected, highly divergent lineage that has been circulating in world poultry production since the early time of IBDV emergence.
Assuntos
Infecções por Birnaviridae/genética , Evolução Molecular , Genoma Viral/genética , Vírus da Doença Infecciosa da Bursa/genética , Doenças das Aves Domésticas/virologia , Animais , Sequência de Bases , Análise Discriminante , Vírus da Doença Infecciosa da Bursa/classificação , Modelos Genéticos , Dados de Sequência Molecular , Aves Domésticas , Análise de Componente Principal , Análise de Sequência de DNA/veterinária , América do Sul , Especificidade da Espécie , Proteínas Estruturais Virais/genéticaRESUMO
A method for counting Infectious pancreatic necrosis virus (IPNV) through epifluorescence microscopy was analyzed in detail. Image processing and statistic considerations are included. The particle size of viruses was compared in different experimental conditions such as the staining of the virus with SYBR-Green I or with antibodies for specific fluorescence labeling of viral proteins. The type of surface used as mounting support was assayed as well. The results indicated that the most suitable method involves the mounting of the viral-containing suspension on a membrane filter followed by the staining with a monoclonal antibody specific for a viral protein combined with a FITC (fluorescein isothiocyanate)-conjugated secondary antibody.