RESUMO
Newcastle disease virus (NDV) is the causative agent of an economically important disease, which affects all species of birds worldwide. Current vaccination programs for NDV include the use of either low-virulent live-virus vaccines or inactivated vaccines to induce protective immunity while producing minimal adverse effects in birds. In order to further characterize the immune response elicited by live virus and inactivated NDV conventional vaccines in chickens, we evaluated the presence of specific antibodies in different secretions and in tissue culture supernatants of immunized birds. To this end, we analyzed all the samples by ELISA, using an indirect assay set up in the laboratory. Specific anti-NDV IgG antibodies were detected in tracheal and cloacal swabs and tracheal and intestinal washes of immunized animals. We also found specific anti-NDV IgG antibodies in tracheal and intestinal tissue culture supernatants, indicating that the IgG found in swabs and washes was not transudated from serum or, at least, was not all transudated from serum. Knowledge about the mechanisms involved in the immune response of chickens to different NDV vaccines should increase our understanding of the mucosal response against the virus and, eventually, provide new useful information for the development and evaluation of synthetic vaccines.
Assuntos
Imunoglobulina G/análise , Doença de Newcastle/prevenção & controle , Vírus da Doença de Newcastle/imunologia , Vacinação/veterinária , Vacinas Virais/administração & dosagem , Animais , Anticorpos Antivirais/análise , Galinhas , Ensaio de Imunoadsorção Enzimática , Testes de Inibição da Hemaglutinação , Imunidade nas Mucosas , Mucosa/imunologia , Testes de Neutralização , Doença de Newcastle/imunologiaRESUMO
Newcastle disease virus (NDV) is the causative agent of an economically important disease, which affects all species of birds worldwide. Current vaccination programs for NDV include the use of either low-virulent live-virus vaccines or inactivated vaccines to induce protective immunity while producing minimal adverse effects in birds. In order to further characterize the immune response elicited by live virus and inactivated NDV conventional vaccines in chickens, we evaluated the presence of specific antibodies in different secretions and in tissue culture supernatants of immunized birds. To this end, we analyzed all the samples by ELISA, using an indirect assay set up in the laboratory. Specific anti-NDV IgG antibodies were detected in tracheal and cloacal swabs and tracheal and intestinal washes of immunized animals. We also found specific anti-NDV IgG antibodies in tracheal and intestinal tissue culture supernatants, indicating that the IgG found in swabs and washes was not transudated from serum or, at least, was not all transudated from serum. Knowledge about the mechanisms involved in the immune response of chickens to different NDV vaccines should increase our understanding of the mucosal response against the virus and, eventually, provide new useful information for the development and evaluation of synthetic vaccines.
Assuntos
Animais , Imunoglobulina G/análise , Doença de Newcastle/prevenção & controle , Vírus da Doença de Newcastle/imunologia , Vacinação/veterinária , Vacinas Virais/administração & dosagem , Anticorpos Antivirais/análise , Galinhas , Ensaio de Imunoadsorção Enzimática , Testes de Inibição da Hemaglutinação , Imunidade nas Mucosas , Mucosa/imunologia , Testes de Neutralização , Doença de Newcastle/imunologiaRESUMO
In this report, we describe the biological and molecular characterization of a paramyxovirus type-1 (PPMV-1) isolate found in wild pigeons in an urban habitat in Buenos Aires, Argentina. Of the nine pigeons captured, three were moribund, and the other six showed diarrhea, ataxia, tremor, torticolis, and wing paralysis. The intracerebral pathogenicity index was 1.29, and the amino acid (aa) sequence at the fusion protein cleavage site was 112GRQ KRF117. These characteristics correspond to a virulent Newcastle disease virus isolate. Nevertheless, it was not possible to reproduce the disease in chickens experimentally although the chickens exhibited seroconversion after inoculation. On the other hand, pigeons inoculated with the isolate became sick. These results provide further evidence about the unusual pathogenicity of PPMV-1 for chickens and show once more the need for more biological determinations in these cases to arrive at a final conclusion.
Assuntos
Columbidae/virologia , Doença de Newcastle/virologia , Vírus da Doença de Newcastle/genética , Sequência de Aminoácidos , Animais , Animais Selvagens , Argentina , DNA Viral/análise , Testes de Inibição da Hemaglutinação/veterinária , Testes de Hemaglutinação/veterinária , Dados de Sequência Molecular , Doença de Newcastle/patologia , Vírus da Doença de Newcastle/patogenicidade , Reação em Cadeia da Polimerase Via Transcriptase Reversa/veterinária , Alinhamento de Sequência/veterinária , Proteínas Virais de Fusão/química , Proteínas Virais de Fusão/genética , VirulênciaRESUMO
Newcastle disease virus (NDV) is an economically important pathogen of poultry that may cause clinical disease that ranges from a mild respiratory syndrome to a virulent form with high mortality, depending on an isolate's pathotype. Infections with virulent NDV strains are required to be reported by member nations to the Office of International Epizootes (OIE). The primary determinant for virulence among NDV isolates is the presence or absence of dibasic amino acids in the fusion (F) protein cleavage activation site. Along with biological virulence determinations as the definitive tests, OIE accepts reporting of the F protein cleavage site sequence of NDV isolates as a virulence criterion. Nucleotide sequence data for many NDV isolates recently isolated from infected chickens and other avian species worldwide have been deposited in GenBank. Consequently, viral genomic information surrounding the F protein cleavage site coding sequence was used to develop a heteroduplex mobility assay (HMA) to aid in further identification of molecular markers as predictors of NDV virulence. Using common vaccine strains as a reference, we were able to distinguish virulent viruses among NDV isolates that correlated with phylogenetic analysis of the nucleotide sequence. This technique was also used to examine NDV isolates not previously characterized. We were able to distinguish vaccine-like viruses from other isolates potentially virulent for chickens. This technique will help improve international harmonization of veterinary biologics as set forth by the OIE and the Veterinary International Cooperation on Harmonization of Technical Requirements of Veterinary Medicinal Products. Ultimately, the HMA could be used for initial screening among a large number of isolates and rapid identification of potentially virulent NDV that continue to threaten commercial poultry worldwide.
Assuntos
Análise Heteroduplex/métodos , Doença de Newcastle/diagnóstico , Vírus da Doença de Newcastle/classificação , Vírus da Doença de Newcastle/genética , Proteínas Virais de Fusão/química , Sequência de Aminoácidos , Animais , Aves , Galinhas , Dados de Sequência Molecular , Doença de Newcastle/virologia , Vírus da Doença de Newcastle/isolamento & purificação , Vírus da Doença de Newcastle/patogenicidade , Filogenia , Análise de Sequência de DNA , Perus , Proteínas Virais de Fusão/genética , VirulênciaRESUMO
We report the construction of a recombinant vaccinia virus expressing the precursor for the four structural proteins of FMD virus (FMDV) (P1) strain C3Arg85 using a procedure for isolation of recombinant vaccinia viruses based solely on plaque formation. Adult mice vaccinated with this recombinant vaccinia virus elicited high titers of neutralizing antibodies against both the homologous FMDV and vaccinia virus, measured by neutralization assays. Liquid phase blocking sandwich enzyme-linked immunosorbent assays (ELISAs) using whole virus as antigen showed high total antibody titers against homologous FMDV, similar to those induced by the conventional inactivated vaccine. When ELISAs were carried out with heterologous strains A79 or O1Caseros as antigens, sera from animals vaccinated with the recombinant virus cross-reacted. Mice boosted once with the recombinant vaccinia virus were protected against challenge with infectious homologous virus. These results indicate that recombinant vaccinia viruses are efficient immunogens against FMDV when used as a live vaccine in a mouse model.
Assuntos
Aphthovirus/imunologia , Vacinas Sintéticas/imunologia , Vaccinia virus/genética , Vacinas Virais/imunologia , Animais , Anticorpos Antivirais/biossíntese , Reações Cruzadas , Feminino , Imunização , Camundongos , Camundongos Endogâmicos BALB C , Vaccinia virus/imunologiaRESUMO
Newcastle disease virus (NDV) remains a major pathogen of poultry where highly virulent strains require reporting to the Office of International Epizootes. NDV is a paramyxovirus existing as different strains classified on the basis of severity of the disease they cause. The present study was conducted in Argentina to determine the prevalence of highly virulent velogenic NDV strains in commercial poultry farms. Tracheal and cloacal swabs from 693 flocks, representing 14% of the broiler production, were collected and pooled. A pool amplified twice in embryonated eggs presented a limited hemagglutination titer. We performed reverse transcription coupled to polymerase chain reaction to amplify fusion and matrix protein gene sequences of the isolate and the strain Trenque Lauquen, isolated in Argentina during an outbreak in 1970-71 and previously characterized as velogenic viscerotropic by biological methods. The amino acid sequences were deduced from nucleotide sequences of the amplification products and the pathotype predicted according to the sequences obtained. From the samples analyzed, we found only one type of NDV, being the isolate identified as lentogenic NDV. This strain is probably the one used in vaccination of flocks where that sample was obtained. These data have allowed us to consider a velogenic NDV-free status in Argentina's commercial poultry.
Assuntos
Galinhas , Doença de Newcastle/prevenção & controle , Vírus da Doença de Newcastle/classificação , Vírus da Doença de Newcastle/genética , Doenças das Aves Domésticas/prevenção & controle , Reação em Cadeia da Polimerase Via Transcriptase Reversa/veterinária , Proteínas Virais de Fusão/genética , Sequência de Aminoácidos , Animais , Argentina , Sequência Consenso , Evolução Molecular , Dados de Sequência Molecular , Doença de Newcastle/epidemiologia , Doença de Newcastle/virologia , Vírus da Doença de Newcastle/patogenicidade , Filogenia , Doenças das Aves Domésticas/epidemiologia , Alinhamento de Sequência , Sorotipagem/métodos , Sorotipagem/veterinária , Proteínas Virais de Fusão/química , VirulênciaRESUMO
The IgG isotype response in Balb/c mice infected with FMDV or immunized with different vaccine formulations using inactivated virus particles as antigen was analyzed at various times post-inoculation. For this purpose an ELISA based on polyclonal antibodies for detection and quantification of mouse IgG isotypes with FMD virus (FMDV) specificity was developed. Three immunomodulators, which have been shown to be very effective in inducing strong and long-lasting antibody responses (Bahnemann, Arch. Virol. 1975, 47, 47-56; Polatnik and Bachrach, Appl. Microbiol. 1964, 12, 368-376), were employed to formulate different vaccines using aqueous and oil vehicles: a water-soluble fraction of the cell wall of Mycobacterium sp., a purified extract of lipopolysacharide from Brucella ovis and a synthetic lipoamide, Avridine. Infected animals between 14 and 60 days post-inoculation (d.p.i.) showed responses dominated by IgG2b, followed by IgG1, IgG2a and IgG3, respectively. The IgG3 isotype was the first, together with IgG1, to be elicited during the first 7 days after infection, whereas no IgG3 activity was detected in vaccinated animals at any time. With formulations including immunomodulators, persisting high levels of IgG2b (similar to those of infected animals) were detected until 180 d.p.i., while with conventional vaccines IgG2b responses were detected up to 60 d.p.i. Animals vaccinated with formulations including these immunomodulators presented an augmented resistance to viral challenge at 210 d.p.i. in relation with those immunized with conventional vaccines. The possible relationship of these differences in the isotype response and protection is discussed.
Assuntos
Aphthovirus/imunologia , Febre Aftosa/imunologia , Isotipos de Imunoglobulinas/biossíntese , Vacinas Virais/imunologia , Adjuvantes Imunológicos/administração & dosagem , Animais , Animais Recém-Nascidos , Especificidade de Anticorpos , Febre Aftosa/prevenção & controle , Imunoglobulina G/biossíntese , Imunoglobulina G/classificação , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Vacinas Virais/administração & dosagemRESUMO
Foot-and-mouth disease is one of the more economically important diseases among meat-producing biungulate species. In contrast to natural infection, current foot-and-mouth disease virus (FMDV) vaccines, prepared with inactivated virus and adjuvants, elicit short-lived protection. The immunomodulating effect on FMDV vaccines of avridine and lipopolysaccharide of Brucella ovis (LPS) was tested in a murine model. The duration of immunity, protection, stimulation of immunocompetent cells producing a long-lasting secondary response and immunoglobulin (Ig) isotypes were examined. The incorporation of either immunomodulator into aqueous and oil vaccines induced a long-lasting specific antibody response. The neutralizing titres and protection were significantly higher than those observed in animals immunized with control vaccines. Data collected from repopulation assays indicated that the immunomodulators used participate in the activation of immune cell populations involved in long-lasting memory. This resulted in an efficient B-cell secondary response even in the absence of T cells, which were necessary for the stimulatory effect of the immunomodulators in donor mice. Avridine and LPS stimulated IgG1, IgG2a and IgG2b production, which was correlated with the improvement of the protection induced by these vaccines.
Assuntos
Adjuvantes Imunológicos/farmacologia , Aphthovirus/imunologia , Brucella/imunologia , Diaminas/farmacologia , Febre Aftosa/imunologia , Febre Aftosa/prevenção & controle , Lipopolissacarídeos/farmacologia , Vacinas Virais/farmacologia , Animais , Linfócitos B/efeitos dos fármacos , Linfócitos B/imunologia , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Imunidade Inata/efeitos dos fármacos , Imunidade Inata/imunologia , Imunoglobulina G/biossíntese , Memória Imunológica/efeitos dos fármacos , Ativação Linfocitária/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Linfócitos T/efeitos dos fármacos , Linfócitos T/imunologia , VacinaçãoRESUMO
The immunomodulating effect of an extract of the cell wall of Mycobacterium sp. (WSF, Vetrepharm Inc., London, Canada) in foot-and-mouth disease virus inactivated vaccines was tested in a murine model. The duration of immunity, protection, stimulation of immunocompetent cells acting on the long-lasting secondary response and possible tissue damage were examined. The incorporation of 10 micrograms WSF into aqueous and oil vaccines induced a high and long-lasting specific antibody response. The neutralizing titres of these antibodies were significantly higher than those observed in animals immunized with vaccines lacking WSF and conferred protection for at least 7 months. The data collected in repopulation assays indicate that WSF participates in the activation of immune cell populations involved in long-lasting memory. This results in an efficient B-cell secondary response even in the absence of T cells, lasting at least 5 months. No adverse reactions were detected. The enhancement effect of WSF on the immune response to foot and mouth disease vaccines observed in the murine model indicates the possibility of its inclusion in aqueous vaccines to be tested in cattle.
Assuntos
Adjuvantes Imunológicos , Aphthovirus/imunologia , Febre Aftosa/prevenção & controle , Mycobacterium/imunologia , Vacinas Virais/imunologia , Animais , Anticorpos Antivirais/biossíntese , Linfócitos B/imunologia , Parede Celular/imunologia , Modelos Animais de Doenças , Cobaias , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Testes de Neutralização , Vacinas de Produtos Inativados/administração & dosagem , Vacinas de Produtos Inativados/imunologia , Vacinas Virais/administração & dosagemRESUMO
The immune response to foot-and-mouth disease virus (FMDV) elicited by infection or immunization with inactivated virus in adult mice was examined. A model of adoptive transfer of immunocompetent cells was used for this purpose. The results presented here indicate that both short- and long-term secondary immune responses elicited by high doses of inactivated virus are indistinguishable, at the humoral or cellular level, from that observed after infection. The responses to inactivated or infectious virus were both efficiently mediated by B cells. However, immunization with low doses of inactivated virus induced a response which, although effective in aborting infection, was fully dependent on FMDV-specific T cell cooperation. These findings suggest that the different immune responses observed after infection and immunization are mainly the result of the different viral mass presented to the immune system in each case.