Experimental infection with Brazilian Newcastle disease virus strain in pigeons and chickens

Abstract This study was designed with the goal of adding as much information as possible about the role of pigeons (Columba livia) and chickens (Gallus gallus) in Newcastle disease virus epidemiology. These species were submitted to direct experimental infection with Newcastle disease virus to evaluate interspecies transmission and virus-host relationships. The results obtained in four experimental models were analyzed by hemagglutination inhibition and reverse transcriptase polymerase chain reaction for detection of virus shedding. These techniques revealed that both avian species, when previously immunized with a low pathogenic Newcastle disease virus strain (LaSota), developed high antibody titers that significantly reduced virus shedding after infection with a highly pathogenic Newcastle disease virus strain (São Joao do Meriti) and that, in chickens, prevent clinical signs. Infected pigeons shed the pathogenic strain, which was not detected in sentinel chickens or control birds. When the presence of Newcastle disease virus was analyzed in tissue samples by RT-PCR, in both species, the virus was most frequently found in the spleen. The vaccination regimen can prevent clinical disease in chickens and reduce viral shedding by chickens or pigeons. Biosecurity measures associated with vaccination programs are crucial to maintain a virulent Newcastle disease virus-free status in industrial poultry in Brazil.

Avaliação de diferentes vias vacinais para vacinação contra o vírus da doença de Newcastle em aves de fundo de quintal / Assessment of different vaccination approaches against Newcastle disease virus in domestic backyard poultry

Foram avaliadas três vias de aplicação vacinal contra o vírus da doença de Newcastle em aves de criatório de fundo de quintal (AFQ) jovens e adultas. Um total de 135 AFQ foram distribuídas em tratamentos distintos de acordo com a via vacinal: via ocular (VO), água de bebida (VAB) e alimentar (VA). Cada tratamento foi representado por 40 aves (20 jovens e 20 adultas) e utilizou-se um grupo-controle de 15 aves não vacinadas. O programa de vacinação estabelecido constou de uma primovacinação e dois reforços vacinais, utilizando-se a cepa La Sota. Para aves jovens, os títulos obtidos pelas VO e VAB não diferiram aos 15, 45 e 140 dias, mas houve diferenças nos títulos das aves vacinadas pela VA. Nas aves adultas, a vacinação pela VO apresentou resultados mais elevados que as vacinações pelas VAB e VA na primeira resposta, aos 15 dias. Aos 45 dias, os títulos obtidos pela VAB foram mais baixos que os obtidos pela VO, e, aos 140 dias, não houve diferença entre as três vias avaliadas. Concluiu-se que as vacinações pelas VO e VAB constituem alternativas eficazes para vacinação de AFQ jovens e adultas.

Three ways of vaccination against Newcastle Disease Virus (NDV) were evaluated in young and adults domestic backyard poultry (DBP). A total of 135 DBP was submitted to three different administration routes of ND vaccine: eye-drop, drinking water, and feed. Each treatment consisted of 40 birds (20 young and 20 adult) and a control group of 15 unvaccinated birds. The treatment consisted of a first vaccination and two boosters, using La Sota strain. For young birds, the eye-drop and drinking water vaccinations presented no differences at 15, 45, and 140 days, differing from the titers obtained by birds treated by feed vaccination method. In the adult birds, the eye-drop administration presented higher titers than by drinking water and feed approaches in the first response to the vaccination at 15 days. At 45 days, the results obtained by the drinking water had lower titers than those from the eye-drop. The three vaccination methods presented no difference at 140 days. In conclusion, the vaccination by eye-drop and drinking water methods constituted an efficient alternative of vaccination for adult and young DBP against Newcastle virus.

[Effect of experimental coccidial infection on cellular immunity induced by newcastle disease vaccination in broilers]

In order to evaluate the possible immunosuppressive effects of coccidial infection on Cell Mediated Immunity [CMI] of broiler chickens, 640 Ross male day old broiler chicks were randomly divided into 4 equal groups of 160 [each consist of 4 replicates of 40]. The negative control group remained unchallenged, while the other three groups challenged with 3 different levels of high, medium and low doses of mixed inoculums of E. acervulina and E. maxima at 15 days of age. For the assessment of CMI, Macrophage Migration Inhibition [MIF] test was performed. For this purpose blood samples were collected at 15, 22, 36 days of age. No significant difference was observed among MIF of different groups at 15 days of age [p>0.05]. At 22 and 36 days of age a significant difference observed among MIF of high dose and control groups [p<0.05]. According to the results, it can be concluded that severe coccidial infection may compromise specific CMI activity in broilers

Locally produced mucosal IgG in chickens immunized with conventional vaccines for Newcastle disease virus

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.

Protective efficacy of commercial inactivated Newcastle disease virus vaccines in chickens against a recent Korean epizootic strain

Despite the intensive vaccination policy that has been put in place to control Newcastle disease virus (NDV), the recent emergence of NDV genotype VII strains in Korea has led to significant economic losses in the poultry industry. We ssessed the ability of inactivated, oil-emulsion vaccines derived from La Sota or Ulster 2C NDV strains to protect chickens from challenge with Kr-005/00, which is a recently isolated Korean epizootic genotype VII strain. Six-week-old SPF chickens were vaccinated once and challenged three weeks later via the eye drop/intranasal route. All vaccinated birds were fully protected from disease, regardless of the vaccine strains used. All vaccinated and challenged groups showed significant sero-conversion 14 days after challenge. However, some vaccinated birds, despite being protected from disease, shed the challenge virus from their oro-pharynx and cloaca, albeit at significantly lower titers than the unvaccinated challenged control birds. The virological, serological, and epidemiological significance of our observations with regard to NDV disease eradication is discussed.

Antiviral activity of bovine uterus and placenta induced by Newcastle disease virus

The antiviral activity profile of the uterus and fetal membranes from bovine placenta, induced by the Newcastle disease virus (NDV) throughout gestation, was investigated. Explants of the endometrium and caruncles were collected from the uterus, and amniochorion, allantochorion and cotyledons, from fetal placenta. Tissue cultures were induced with ~6.0 hemagglutinating units (HU) of NDV. Supernatants were concentrated 20 fold, filtered in 100kDa cut-off membranes and antiviral activity was titrated in MDBK x VSV system. Tissues of the uterus did not exhibit antiviral activity, while allantochorion and amniochorion produced antiviral factors throughout gestation. Antiviral factors were not related with IFN-alpha, gamma, tau or TNF-alpha. The antiviral activity pattern observed showed to be related with the development of fetal membranes and increased at the end of pregnancy. Such data suggest that IFN genes inducible by virus are present in fetal membranes of the cow placenta and their expression is dependent on the age of gestation.

Investigou-se a atividade antiviral do útero e da placenta bovina, ao longo da gestação, induzidos pelo vírus da doença de Newcastle (NDV). Explantes do endométrio e carúnculas foram colhidos do útero. Os tecidos corioamniótico, corioalantóide e cotilédones foram dissecados da placenta fetal. Os cultivos celulares foram induzidos com aproximadamente 6,0 unidades hemaglutinantes do NDV. Os sobrenadantes foram concentrados 20 vezes, filtrados em dispositivos com superfície de separação de 100kDa e a atividade antiviral foi titulada em células MDBK e vírus da estomatite vesicular (VSV). Endométrio, carúnculas e cotilédones não apresentaram atividade antiviral. Corioamniótico e corioalantóide produziram fatores antivirais ao longo da gestação. Estes fatores não foram relacionados aos IFN - alfa, gama ou tau e nem ao TNF - alfa. O padrão de produção de fatores antivirais acompanhou o desenvolvimento dos tecidos fetais e títulos mais altos foram observados no final da gestação. Estes dados sugerem que os genes de IFNs induzidos por vírus localizam-se nas membranas fetais da placenta e a expressão desses genes é dependente do estádio da gestação.

Mycobacterium phlei as an oral immunomodulator with Newcastle disease vaccine.

Experiments were conducted in chickens to understand the effects of oral immunomodulation. Heat inactivated M phlei, a commensal Mycobacterium and a non-specific immunomodulator, was administered orally prior to live Newcastle disease F (ND F) strain vaccination. In experimental birds it lead to an enhanced cell mediated Immune response (CMI) against the vaccine. There was a reduction in the Haemagglutination inhibiting (HI) antibodies. However, it did not affect the protection against a virulent challenge, as the protection percentage was more or less same in vaccinated birds irrespective of the M.phlei administration. M. phlei administration could not enhance the immune response to inactivated ND F vaccine administered orally. The results indicate that M. phlei favours a CMI response to orally administered live ND F vaccine. It may be of potential use in enhancing CMI against vaccines and a cheaper alternative to costlier recombinant cytokines.

Monoclonal antibody based dot-enzyme linked immunosorbent assay (Dot-ELISA) and agar gel precipitation test (AGPT) for identification of Newcastle disease virus (NDV).

Two mouse monoclonal antibodies (MAbs), viz. 2B7 and 2 D10 raised against haemagglutinin-neuraminidase glycoprotein of Newcastle disease virus (NDV) were used to identify several other field isolates and vaccine strains of NDV. These MAbs reacted specifically with all the NDV strains/isolates in Dot-ELISA whereas, only MAb 2D10 reacted with all the NDV strains/isolates in agar gel precipitation test. These two tests employing the MAbs were standardised for rapid diagnosis and identification of NDV.

Inoculación experimental del paramixovirus del ojo azul en el gato doméstico (Felis catus) / Experimental inoculation of blue eye paramyxovirus in the cat (Felis catus)

En este trabajo se seleccionó al gato doméstico, debido a que la población felina tiene amplia distribución dentro de las granjas porcinas, principalmente por ser usada como control de roedores. Quince gatos adultos fueron inoculados con 4 ml de paramixovirus de ojo azul (POA) con un título de 10 DICC/ml por vía intranasal aplicado como bomba de aspersión. A los 0, 14 y 21 días (PI) se obtuvieron muestras séricas para detección de anticuerpos contra POA por las pruebas de inhibición de la hemoglutinación beta (IHA) y seroneutralización método beta (SN). Para el aislamiento viral se tomó hisoponasal y ocular a los 4 días, y biopsia de tonsila a los 7 días. Los animales fueron sacrificados a los 21 días posinoculación (PI). Se tomaron muestras de encéfalo, pulmón y tonsila para las prueba de inmunofluorescencia (IF) directa y para estudio histopatológico (HP). Todas las muestras de biopsia de tonsila e hisopo nasal y ocular fueron negativas en cultivo celular (CC) en los tres pases ciegos. En la prueba de IHA se obtuvieron los siguientes resultados: el primer muestreo fue negativo y el segundo y tercero detectaron títulos entre 1:6 y 1:192. En las SN, el primer muestreo fue negativo y en el segundo y tercero se detectaron títulos entre 1:4 y 1:64. La IF directa de órganos fue negativa para pulmón, tonsila y encéfalo. En el estudio HP no hubo cambios significativos. De los resultados obtenidos se concluye que el gato tiene la capacidad de seroconvertir a POA sin ser necesariamente un portador

Evaluación de una vacuna experimental contra ojo azul en cerdos mediante las pruebas de inmunogenicidad, inocuidad, potencia y medición de la inmunidad pasiva en lechones / Evaluation of the passive immune response and protection confered by a blue eye inactivated vaccine in pigs

El ojo azul (OA) es una enfermedad de etiología viral que se caracteriza por producir encefalitis en lechones, falla reproductiva y opacidad corneal. Sin embargo, todavía no se cuenta con una vacuna para prevención y control de esta enfermedad. EL objetivo de este estudio fue evaluar la respuesta inmune y la protección conferida por una vacuna inactivada contra OA. Para la prueba de inmunogenicidad e inocuidad se usaron 10 cerdos destetados, fueron vacunados a las 6 y 8 semanas de edad. Se midió la respuesta inmune humoral por la prueba de sueroneutralización (SN) frente a 100 dosis infectantes cultivo celular 50 por ciento (DICC 50 por ciento) por ml del paramyxovirus de ojo azul cepa 1987 (POA-87). Los resultados de la prueba de SN indicaron que la media de anticuerpos fue de 1:32. No se presentaron reacciones locales o generalizadas, ni aumento en la temperatura de los cerdos vacunados y no vacunados en contracto (mezclados). Se midieron los niveles de Acs por SN cada mes y 6 meses después de la primera aplicación de la vacuna. Se realizó una prueba intradérmica (ID) observándose en la zona de inoculación una reacción de hipersensibilidad tipo IV en 3 de los 7 cerdos inoculados con POA-87 purificado. Además fueron vacunadas 6 hembras gestantes a las 4 y 2 semanas preparto, se midió la respuesta inmune humoral en el suero y calostro de las hembras y se determinó el grado de inmunidad pasiva transmitida, midiendo los niveles de Igs en el suero de los lechones a los 4, 28, y 38 días de edad. En este caso, la media de Acs por SN fue mayor a 1:16, con disminución del 85 por ciento a los 28 días y del 100 por ciento a los 38. En la prueba, de potencia se utilizaron 2 cerdas gestantes, una recibió dos aplicaciones de vacuna antes del parto. El desafío de las dos camadas se hizo a los cuatro días posparto; se observó mortalidad del 100 por ciento en los lechones de la hembra no vacunada, y protección del 71.4 por ciento en los lechones de la madre vacunada. La SARH señala como requisito mínimo un 80 por ciento de protección; sin embargo, de acuerdo con los resultados y análisis comparativos realizados se concluye que la vacuna inactivada contra el paramixovirus del ojo azul (POA) en cerdos, objeto de esta investigación, deberá ser sometida a un estudio con un mayor número de animales para comprobar que este biológico puede alcanzar una protección mayor al 80 por ciento y que es apta para el control de la enfermedad del Ojo Azul

Efeito dos vírus da leucose linfóide e da doença bursal infecciosa sobre a vacinaçäo contra a doença de Newcastle / Effect of the lymphoid leukosis virus and infections bursal disease on the vaccination against Newcastle disease

O presente trabalho, compreende a montagem de vários experimentos para melhor estudar o efeito da infecçäo congênita com o vírus da leucose linfóide (VLL) e a infecçäo com o vírus da doença bursal infecciosa (VDBI), sobre a proteçäo conferida pela cepa LaSota do vírus da doença de Newcastle (VDN), em aves Leghorn brancas pertencentes ao plantel da Area de Avicultura da Estaçäo Experimental da PESAGRO-Rio, Km 47 - Rodovia Rio/Säo Paulo - Itaguaí, RJ. Aos 21 dias de idade todas as aves foram numeradas e sangradas por punçäo da veia radial direita para separaçäo e colheita de amostras de soro sanguíneo, enquanto que os lotes de números pares foram infectados com VDBI por via ocular. Com a idade de 28 dias, os lotes 1, 2, 5, 6, 9, 10, 13 e 14 foram vacinados contra DN com cepa LaSota por via nasal. Aos 56 dias as aves pertencentes aos lotes vacinados foram agredidas com vírus velogênico da doença de Newcastle (VVDN) e quando completaram 126 dias as aves pertencentes aos lotes 1, 2, 5, 6, 9, 10, 13, 14, 15 e 16 também foram agredidas. O efeito da infecçäo com VLL e o VDBI sobre a proteçäo conferida pela cepa LaSota e agressäo com uma cepa velogênica do VDN variou de modo significativo. Com referência aos congenitamente infectados com VLL esta proteçäo, nas mesmas circunstâncias variou de 66,7% a 100%, percentuais estes relativos às aves portadoras das duas infecçöes, o que demonstra que as aves portadoras de VLL e do VDBI säo mais deficientes do que aquelas infectadas somente com um dos agentes

Influencia de algunos preservativos conservadores sobre la efectividad de una vacuna contra la enfermedad del Newcastle / Influence of some conservative preservative on the efficiency of a vaccine against Newcastle disease

La estructura viral puede verse afectada por la presencia de ciertos compuestos químicos. Se demuestra un aumento en el tiempo de mortalidad de embriones de pollo que recibieron virus expuestos a conservadores como el fenol o el metil y el propil parabeno, lo que indica una disminución significativa en el número de partículas virales viables capaces de causar infección. Por hemoaglutinación también se demuestra un incremento relativamente pequeño y lento en el número de virus, en función de un tiempo determinado, en el líquido alaitoideo de embriones inoculados con virus expuestos a fenol y parabenos, a diferencia de otros embriones que recibieron vacunas expuestas a conservadores como la penicilina y estreptomicina con o sin tampón fosfato. El uso de vacunas tratadas con fenol o parabenos, previo a su administración en pollitos, dieron títulos serológicos de inhibición de la hemoaglutinación bastante bajos, demostrando también la importancia del uso adecuado de conservadores apropiados en una formulación vacunal