Immuno-protective effect of commercial IBD vaccines against emerging novel variant infectious bursal disease virus in specific-pathogen-free chickens.

IMPORTANCE: Infectious bursal disease (IBD) is an important viral poultry disease that vaccination can control. OBJECTIVE: This study examined the immune protection of immune-complex (Vaccine A) and attenuated live (Vaccine B) IBD vaccines in specific-pathogen-free (SPF) chickens against a novel Malaysian variant IBD virus (vaIBDV) challenge. METHODS: One-day-old (n =75) SPF chickens were divided randomly into the following three groups of 25 chicks each: Control, Vaccine A, and Vaccine B groups. The vaIBDV strain, UPM1432/2019, was used for the challenge at 21 and 28days post-vaccination (dpv). Five birds from unchallenged and challenged groups were sacrificed seven days post-challenge, and blood, bursa, spleen, and cloacal swabs were collected. The IBD antibodies (Abs), lymphoid lesions, and viral load were determined. RESULTS: The UPM1432/2019 virus induced bursal damage in vaccinated SPF chickens despite Ab titers. The mean Ab titers of the Vaccine A challenged group were significantly lower (p < 0.002) than in the unchallenged group at 28 dpv. The bursal indices of the vaccinated unchallenged groups did not differ significantly from those of the vaccinated challenged groups (p = 0.94). Microscopically, the bursae of the challenged groups showed significant atrophy. The bursal lesion score was higher (p < 0.05) in the control and Vaccine B challenged groups than the Vaccine A challenged group. The challenged group had a higher viral load than the vaccinated groups (p < 0.001). CONCLUSIONS AND RELEVANCE: Neither vaccine fully protected against a vaIBDV challenge, highlighting the limitations of current vaccines and the need for further research.

Alteration in the Population of Intraepithelial Lymphocytes and Virus Shedding in Specific-Pathogen-Free Chickens Following Inoculation with Lentogenic and Velogenic Newcastle Disease Virus Strains.

Intraepithelial lymphocytes (IELs) provide the first line of immunological defense after the invasion of the intestine by a pathogen. To understand the changes of IEL response in chickens, we measured the population of different subsets of avian IELs at different time points after primary inoculation of Newcastle disease virus (NDV) lentogenic strain (LaSota) and subsequent challenge with NDV velogenic strain- genotypes VII and VIII. Furthermore, NDV shed after each treatment was quantified. Specific-pathogen-free chickens were randomly divided into six groups of chickens, one to six, inoculated with phosphate buffered saline; NDV lentogenic strain (LaSota); genotype VII (GVII); LaSota and challenged with GVII (LSGVII); genotype VIII (GVIII); and group of LaSota and challenged with GVIII (LSGVIII). The chickens were euthanized at 12, 36, and 60 h postchallenge. Immunophenotyping of CD25+ IEL, CD3+ cells, CD4+ cells, and CD8+ cells was conducted using flow cytometer. Furthermore, virus shedding was measured using reverse transcriptase-quantitative polymerase chain reaction. Data were analyzed using a two-way analysis of variance (ANOVA). The results showed that the percentage population of IEL subsets was generally lower in the chickens inoculated with GVII or GVIII when compared with LaSota, LSGVII and LSGVIII inoculated groups. The NDV copy number was significantly higher in chickens challenged with NDV GVII or GVIII when compared with chickens inoculated with LaSota, LSGVII or LSGVIII. Taking together, NDV velogenic strain caused decrease in the population of subsets of chickens' IEL. However, inoculation of NDV LaSota may increase the population of avian IEL subsets and decrease shedding of virulent NDV.

Expression Profiles of Immune-Related Genes and Apoptosis Study of Avian Intraepithelial-Natural Killer Cells in Chickens Inoculated with Vaccine Strain of Newcastle Disease Virus (NDV) and Challenged with Virulent NDV.

In spite of the available information on the role of natural killer (NK) cells in several viral infections, the interactions between chicken intraepithelial-NK (IEL-NK) cells and Newcastle disease virus (NDV) are poorly understood. In this study, we investigated these interactions following the inoculation of chickens with NDV vaccine strain LaSota and subsequent challenge with velogenic NDV (vNDV) genotype VII (GVII) and VIII (GVIII), through quantification of IEL-NK cell's apoptosis and expression profiling of its surface receptors. Specific-pathogen-free chickens were randomly divided into six groups, as follows: one group of an uninfected control, one group infected with NDV LaSota, two groups each infected with either GVII or GVIII, and two groups inoculated with NDV LaSota and challenged with either GVII (LaSota-genotype VII [LSGVII]) or GVIII (LaSota-genotype VIII [LSGVIII]). Avian intraepithelial lymphocytes (IEL) were isolated from the duodenal loops, and CD3- cells were characterized. Immunophenotyping and apoptosis analysis of CD3-/CD25+/CD45+IEL NK cells were conducted using a flow cytometer. In addition, a gene expression study was conducted using real-time quantitative PCR. Data were analyzed using two-way analysis of variance. The results showed that vNDV GVII or GVIII caused apoptosis of IEL-NK cells; however, following inoculation of LSGVII or LSGVIII, the effect of vNDV GVII and GVIII to cause a reduction in the population of viable IEL-NK cells was significantly reduced. Furthermore, the expression profiles of activating receptors CD69, NK-lysin, and IFN-γ, were generally upregulated in chickens inoculated with LSGVII or LSGVIII. In contrast, B-NK, an inhibitory receptor, was downregulated in these treatment groups. In NDV GVII- and GVIII-challenged groups, however, B-NK was upregulated, whereas the other receptors were generally downregulated. The findings of this study showed that NDV vaccine strain LaSota may prevent apoptosis and cause upregulation of activating receptors of chicken IEL-NK cells in velogenic virus-challenged settings.

Perfiles de expresión de genes relacionados con la inmunidad y estudio de apoptosis de células asesinas naturales intraepiteliales aviares en pollos inoculados con la cepa vacunal del virus de la enfermedad de Newcastle (NDV) y desafiados con de Newcastle virulento. A pesar de la información disponible sobre el papel de las células asesinas naturales (NK) en varias infecciones virales, se conoce poco acerca de las interacciones entre las células NK intraepiteliales de pollo (IEL-NK) y el virus de la enfermedad de Newcastle (NDV). En este estudio, investigamos estas interacciones luego de la inoculación de pollos con la cepa vacunal LaSota y con el desafío posterior con los genotipo VII (GVII) y VIII (GVIII) velogénico de NDV (vNDV), mediante la cuantificación de la apoptosis de las células IEL-NK y los perfiles de expresión de sus receptores de superficie. Los pollos libres de patógenos específicos se dividieron aleatoriamente en seis grupos, de la siguiente manera: un grupo de control no infectado, un grupo infectado con LaSota, dos grupos cada uno infectado con GVII o GVIII, y dos grupos inoculados con LaSota y desafiados con ya sea el genotipo GVII (LaSota-genotipo VII [LSGVII]) o con el genotipo GVIII (LaSota-genotipo VIII [LSGVIII]). Se aislaron células NK intraepiteliales de pollo de las asas duodenales y se caracterizaron las células CD3-. La inmunofenotipificación y el análisis de apoptosis de las células NK CD3-/CD25+/CD45+IEL se realizaron utilizando citometría de flujo. Además, se realizó un estudio de expresión de genes mediante PCR cuantitativa en tiempo real. Los datos se analizaron utilizando un análisis de varianza de dos vías. Los resultados mostraron que el virus de Newcastle genotipos GVII o GVIII causaron apoptosis de células NK intraepiteliales; sin embargo, después de por los tratamientos LaSota-genotipo VII o LaSota-genotipo VIII, el efecto de del virus virulento de Newcastle GVII y GVIII para provocar una reducción en la población de células NK intraepiteliales viables se redujo significativamente. Además, los perfiles de expresión de los receptores activadores CD69, NK-lisina e IFN-γ generalmente aumentaron en pollos inoculados con los tratamientos LaSota-genotipo VII o LaSota-genotipo VIII. Por el contrario, B-NK, que es un receptor inhibidor, se reguló a la baja en estos grupos de tratamiento. Sin embargo, en los grupos expuestos a los virus de Newcastle genotipos GVII y GVIII, el gene B-NK estaba regulado al alza, mientras que los otros receptores generalmente estaban regulados a la baja. Los hallazgos de este estudio mostraron que la cepa vacunal LaSota puede prevenir la apoptosis y causar una regulación al alza de los receptores activadores de las células NK intraepiteliales de pollo en entornos expuestos al virus velogénico.

A retrospective study of bovine tuberculosis at the municipal abattoir of Bauchi State, Northeastern Nigeria.

BACKGROUND AND AIM: Bovine tuberculosis (bTB) still remains a major zoonotic bacterial disease affecting livestock and humans worldwide. The disease remains a poorly managed tropical disease in most developing countries of the world; where in addition to productivity losses and significance in international trade, it posed a major public health threat to both humans and animals. A retrospective study was designed to investigate the occurrence of bTB lesions at Bauchi municipal abattoir. MATERIALS AND METHODS: The study utilized abattoir records spanning a period of 10 years (2004-2013). The records indicated that a total of 1,08,638 heads of cattle comprising n = 56,070 males and n = 52,570 females were slaughtered at the municipal abattoir during the study period. RESULT: Of these heads, n = 1230 (1.13%) (95% confidence interval [CI]: 1.07, 1.19) had tuberculous lesions. The annual occurrence during the study period varied significantly (p<0.001) from 0.53% (95% CI: 0.40, 0.67) to 1.87% (95% CI: 1.66, 2.10) in 2010 and 2012, respectively. Females had a significantly higher (p<0.001) prevalence of 2.10% (95% CI: 1.98, 2.23) compared with the males 0.23% (95% CI: 0.19, 0.27). The distribution of suspected gross bTB lesions in different organs showed 11.87% in the lungs, 5.93% in the liver, 1.14% in the heart, and 0.49% accounted for generalized bTB. However, none was observed on the lymph nodes and intestines. CONCLUSION: It can be concluded that bTB persists in Bauchi State with annual variations during the study period. This study highlights the importance of meat inspection as an important tool for detecting the presence of bTB lesions.

Seroprevalence of brucellosis among cattle slaughtered in three municipal abattoirs of Gombe state, Northeastern Nigeria.

AIM: A cross-sectional study was conducted to determine the seroprevalence of bovine brucellosis among cattle slaughtered at three municipal abattoirs of Gombe State, Nigeria. MATERIALS AND METHODS: A total of 200 blood samples collected from slaughtered cattle of different breeds (Sokoto Gudali - 50, White Fulani - 102, Red bororo - 34, and Crossbreeds - 14), sex (males - 19 and females - 181), and from different locations (Billiri - 30, Yamaltu Deba - 50, and Gombe - 120) were screened for brucellosis using rose bengal plate test (RBPT), serum agglutination test (SAT), and microtiter agglutination test (MAT). RESULTS: Of the 200 serum samples analyzed, 7 (3.5%), 10 (5.0%) and 18 (9.0%) were positive by RBPT, SAT and MAT, respectively. The results showed no statistically significant association between sex and seropositivity to bovine brucellosis. However, seropositivity of bovine brucellosis was higher in females than in males. Similarly, no statistically significant association was observed between breed and occurrence of bovine brucellosis. Moreover, the prevalence of brucellosis was higher in Sokoto Gudali as compared with the other breeds. Based on the study locations, higher seroprevalence was observed in animals screened from Billiri as compared with those from other locations (p<0.05). CONCLUSION: The presence of Brucella abortus antigen in the sera of slaughtered cattle in Gombe state poses a significant public health risk. Therefore, it is important to carry out further epidemiological studies on fulani herdsmen and cattle herds in the study area, in order to explore the risk factors associated with the occurrence and perpetuation of brucellosis among cattle herds, ascertain the prevalence and status of the disease among both farms and nomadic herds.