ISOLATION AND DETECTION OF NEWCASTLE DISEASE VIRUS FROM FIELD OUTBREAKS IN BROILER AND LAYER CHICKENS BY REVERSE TRANSCRIPTION–POLYMERASE CHAIN REACTION

Serological detection of Newcastle disease virus in backyard poultry production system in Woliso District South West Shewa, Central Ethiopia

BACKGROUND

Newcastle disease (ND) is one of the most important respiratory viral diseases. The disease is endemic in many parts of Ethiopia. However, there is no clear record about the introduction of the virus to the country (Ethiopia). Hence, detail about the ND is very important in its (ND) control and prevention. Despite these facts, there is no available research work done on ND in the current research area that would help either as references for researchers or that could help in the control and prevention of the disease. Therefore, the objective of this study was to detect the ND virus (NDV), using serological methods in from December 2018 to November 2019.

METHODOLOGY

A cross-sectional type of study was conducted to detect the NDV. The convenience sampling method was used for sample data collection. Before data collection, chicken with previous history of vaccination against the NDV was excluded from the sampling animals. Then, a total of 348 blood samples of 2 mL were collected from the brachial vein in 3 mL disposable syringes. The serum was collected in labeled 2 mL cryovial tubes. Indirect enzyme-linked immunosorbent assay (ELISA) tests were performed to detect antibodies against NDV and to determine its antibody titer. The test was performed using (ID.vet innovative version 2) procedure.

RESULT

In the indirect ELISA test, 37.64% (131/348) were positive and antibody titer mean value of (1761.9088) was scored. The standard deviation of 2592.42160 and a percentage coefficient of variation of 147% was scored.

CONCLUSION

From the finding, we conclude that indirect ELISA test detected the presence of the NDV in the study area and the heterogeneousity of antibody titer in the study area. Therefore, further molecular characterization and epidemiological investigation should be carried and vaccination of animals is critical in the study area.

Epidemiology of Newcastle disease in chickens of Ethiopia: a systematic review and meta-analysis

The objective of this systematic review was to estimate the overall pooled prevalence of Newcastle disease in chickens in Ethiopia and identify the sources of heterogeneity among and within studies. The seroprevalence of Newcastle disease was estimated using a single-group meta-analysis. Attempts were also made to identify study-level variables that could explain the heterogeneity in the apparent seroprevalence of the Newcastle disease. The findings were based on 16 published articles and 33 district-level reports and were limited to studies performed during 2005-2017. Due to the presence of heterogeneity, pooled analysis from different districts was conducted using random-effects meta-analysis. The single-group summary of Newcastle disease seroprevalence in chickens was estimated to be 21.47% (19.54-23.4%) with a 95% confidence interval. Our results indicated high inter-study variability (Cochran's Q statistic = 196.2, true variance (τ²) = 0.36, inverse variance index (I²) = 90.0%, p < 0.001). Of all variables analysed, diagnostic techniques and regions were the most significant predictors (p ˂ 0.05) of heterogeneity. According to the diagnostic technique-based meta-analysis of random pooled prevalence, the haemagglutination inhibition test had the highest prevalence, followed by the enzyme-linked immunosorbent assay. In conclusion, the high-pooled prevalence estimates of the disease, combined with the scarcity of published data for the entire country of Ethiopia, indicate a significant data gap on the distribution of Newcastle disease in the country. While the high pooled prevalence tells the need for intervention to control the disease, there is also a need to assess the disease prevalence in all other parts of the country.

Epidemiology of Newcastle disease in Africa with emphasis on Côte d'Ivoire: A review

For decades, Newcastle disease (ND) has long been recognized as a frontline viral disease that constrains poultry production throughout Africa. The need to update on the epidemiology of the disease is rife, due to the increasing importance of poultry farming. In addition, poultry farming serves as the top animal food source globally. However, in Africa, the greater population of poultry is reared under traditional and conventional husbandry methods. This hugely impedes the ability of management practices to be correctly embraced in limiting or excluding viral pathogens in the poultry production chain. We conducted this review to consolidate recently published studies in the field and provide an overview of the disease. We reviewed original studies conducted on ND, the current taxonomic classification of the virus, clinical signs of the disease, and laboratory diagnostic methods available for virus detection and typing. This review additionally examined the control methods currently used, including available or circulating vaccines, vaccinations, recent vaccine findings, and the main variants of the virus present in West Africa. More specifically, we present a review of the current status and available information on the disease in Côte d’Ivoire. The lack of up-to-date and relevant information on the current prevalence, socio-economic impact, and ethnoveterinary medicine used against ND is probably the main limitation for appropriate and effective decision-making for better control of this disease in Côte d’Ivoire.

Comparison of tracheal and choanal cleft swabs and poultry dust samples for detection of Newcastle disease virus and infectious bronchitis virus genome in vaccinated meat chicken flocks

This study assessed different methods (tracheal and choanal cleft swabs from individual birds, and poultry dust as a population level measure) to evaluate the shedding kinetics of infectious bronchitis virus (IBV) and Newcastle disease virus (NDV) genome in meat chicken flocks after spray vaccination at hatchery. Dust samples and tracheal and choanal cleft swabs were collected from four meat chicken flocks at 10, 14, 21 and 31 days post vaccination (dpv) and tested for IBV and NDV genome copies (GC) by reverse transcriptase (RT)-PCR. IBV and NDV GC were detected in all sample types throughout the study period. Detection rates for choanal cleft and tracheal swabs were comparable, with moderate and fair agreement between sample types for IBV (McNemar's = 0.27, kappa = 0.44) and NDV (McNemar's = 0.09; kappa = 0.31) GC respectively. There was no significant association for IBV GC in swabs and dust samples (R2 = 0.15, P = 0.13) but NDV detection rates and viral load in swabs were strongly associated with NDV GC in dust samples (R2 = 0.86 and R2 = 0.90, P<0.001). There was no difference in IBV and NDV GC in dust samples collected from different locations within a poultry house. In conclusion, dust samples collected from any location within poultry house show promise for monitoring IBV and NDV GC in meat chickens at a population level and choanal cleft swabs can be used for detection of IBV and NDV GC instead of tracheal swabs in individual birds.

Development, Biological Characterization, and Immunological Evaluation of Virosome Vaccine against Newcastle Disease in Pakistan

Newcastle disease (ND) is a highly fatal, infectious, viral disease, and despite immunization with live and inactivated vaccines, the disease is still endemic, causing heavy morbidity and mortality leading to huge economic losses to the poultry industry in Pakistan. Therefore, the present study was aimed for the first time in the country at using novel virosomal technology to develop the ND vaccine using an indigenous highly virulent strain of the virus. ND virosome was prepared using Triton X-100, and SM2 Bio-Beads were used to remove the detergent and reconstitute the viral membrane into virosome. Confirmation was done by transmission electron microscopy and protein analysis by SDS-PAGE. In vitro cell adhesion property was observed by incorporating green fluorescent protein (GFP), producing plasmid into virosome and in vitro cell culture assay. Sterility, safety, and stability of the vaccine were tested before in vivo evaluation of immunogenicity and challenge protection study in commercial broiler. The virosome vaccine was administered (30 μg/bird) at days 7 and 14 through the intranasal route in comparison with commercially available live and inactivated ND vaccines. Results revealed significantly high (p < 0.05) and clinically protective hemagglutination inhibition (HI) antibody titers at 7, 14, 21, and 28 days postimmunization with the virosome vaccine in comparison to the negative control. The GMTs were comparable to live and inactivated vaccines with nonsignificant (p > 0.05) differences throughout the experiment. Antibody levels increased in all vaccinated groups gradually from the 7^th day and were maximum at 28^th-day postvaccination. In the virosome-administered group, GMT was 83.18 and 77.62 at 21^st and 28^th-days postvaccination, respectively. Challenge revealed 100%, 90%, and 80% protection in virosome, live, and inactivated vaccinated groups, respectively. Under given experimental conditions, we can conclude that ND virosome vaccine prepared from the indigenous virus was found to be safe and immunogenic.

Molecular and pathological characterisation of genotype VII Newcastle disease virus on Egyptian chicken farms during 2016-2018

Newcastle disease virus (NDV) remains a constant threat to the poultry industry even with intensive vaccination programmes. In the present study, 40 samples were collected from farms showing high mortalities in some Egyptian governorates between 2016 and 2018. Tracheal samples were collected for virus isolation and confirmed by real-time RT-PCR. Molecular characterisation was performed by sequencing, followed by phylogenetic analysis of the novel sequences. Histopathological and immunohistochemical examinations were performed on different organs from NDV-infected broilers. The phylogenetic analysis revealed that the NDV isolates from different areas of Egypt were genetically closely related and all belonged to genotype VII. The histopathological hallmarks included haemorrhagic tracheitis, interstitial pneumonia with syncytia formation, haemorrhagic proventriculitis, necrotising pancreatitis, pan-lymphoid depletion, non-suppurative encephalitis and nephritis. Immunological detection of NDV antigen clarified the widespread presence of viral antigen in different organs with severe lesions. The present study confirmed that a virulent NDV of genotype VII became the predominant strain, causing severe outbreaks in poultry farms in Egypt. The presence of viral antigen in different organs indicates the pantropic nature of the virus. Immunohistochemistry was a very useful diagnostic tool for the detection of NDV antigen.

Detection of Newcastle Disease Virus (NDV) in Laughing Doves and the Risk of Spread to Backyard Poultry

Newcastle disease (ND) is a highly infectious viral disease of birds caused by the Newcastle disease virus (NDV) and doves have been incriminated in previous outbreaks of the disease that have discouraged backyard poultry productions. This survey was done to detect and characterize the NDV from 184 swabs from the cloacae and pharynxes of 67 trapped laughing doves and 25 backyard poultry birds. The study utilized haemagglutination assay (HA) followed by haemagglutination inhibition (HI) tests on HA positive samples to screen field samples. Conventional reverse transcriptase polymerase chain reaction (RT-PCR) was conducted on the HI positives to characterize the NDV. This study revealed that of 134 dove samples screened, 88 (65.7 %) were HA positive. Of these HA positives subjected to HI testing, 37 (42.1 %) were HI positive. Interestingly, 21 (56.8 %) of the HI positives were also RT-PCR positive: 8 lentogenic, 12 velogenic, while one had both lentogenic and velogenic NDV. Comparatively, of the 50 chicken samples screened, 23 (46 %) were HA positive; and of these, HA positives subjected to HI testing, 16 (69.6 %) were HI positive. Only 4 (25 %) of the HI positives were RTPCR positive: 3 lentogenic and a velogenic NDV. From this study it was concluded that laughing doves were demonstrated to be infected with either lentogenic or velogenic NDV or both. The use of red blood adsorption-de-adsorption concentration of NDV enhanced the RT-PCR detection using the fusion gene primers NDV-F 4829 and NDV-R 5031. The detection of not only lentogenic but velogenic NDV in laughing doves poses a great risk to backyard poultry production.

Epidemiological assessment of clinical poultry cases through the government veterinary hospital-based passive surveillance system in Bangladesh: a case study

An epidemiological assessment of clinical poultry cases recorded through the existing passive surveillance at Kishoreganj District Veterinary Hospital during February-March 2016 was performed. A total of 200 cases (87 layers, 80 broilers, 21 ducks, and 12 pigeons) were included in this evaluation. The present study attempted to demonstrate the usefulness of passive surveillance data in quantifying the relative burden of poultry cases and their distribution along with drug prescription patterns. The cases were diagnosed based on clinical history, clinical signs, and observable post-mortem lesions by the registered veterinarian or intern veterinarian. The most prevalent diseases in chickens were infectious bursal disease (IBD) (31.7%; CI (confidence interval) 24.7-39.3%), coccidiosis (22.8%; CI 16.6-29.8%), Newcastle disease (ND) (21.6%; CI 15.5-28.5%), and coli-enteritis (8.4%; CI 4.6-13.6%). The most prevalent disease in ducks was duck plague (DP) (76.6%; CI 52.8-91.7%). Newcastle disease was most prevalent (66.7%; CI 34.8-90.0%) in pigeons. Infectious bursal disease, aspergillosis, and colibacillosis respectively were seen in a higher proportion of cases in broiler chickens than in layer chickens (58.7%, 12.5%, and 11.2% vs. 6.9%, 1.1%, and 3.4%; p ≤ 0.05). Contrarily, ND was seen in greater proportion of cases in layer chickens (32.1%) than in broiler chickens (10.0%) (p < 0.001). Infectious bursal disease, ND, coccidiosis, and aspergillosis were higher in older age broilers than in younger broilers (p ≤ 0.05). Antibiotics were often used to treat the poultry diseases such as trimethoprim with sulpha drugs (41%), ciprofloxacin (39%), sulphadiazine (27.5%), and erythromycin (26%). Through the present study, we can see how a passive surveillance system would be an effective tool for delineating disease distributions and common treatment regimens, thus helping to mitigate disease prevalence.

Patho-epidemiological study on Genotype-XIII Newcastle disease virus infection in commercial vaccinated layer farms

Aim:

The present research work was carried out to study the patho-epidemiological aspects of Genotype-XIII Newcastle disease virus (NDV) infection in commercial layer in and around Anand, Gujarat. As the outbreaks have reported in vaccinated flocks, it was felt necessary to study the disease with respect to its changing pathogenicity and relevant aspects.

Materials and Methods:

The study comprised of patho-epidemiology of Newcastle disease (ND) by information collected from different layer farms suffering from the disease in relation to incidence pattern and mortality, duration of mortality, susceptible age, and loss due to production performance. Clinical signs were recorded based on observations. During post-mortem, gross lesions were also recorded. For histopathological examination visceral organs according to lesions were collected in 10% formalin and processed slide stained by hematoxylin and eosin for microscopic examination. Cultivation of virus was done in embryonated specific pathogen-free (SPF) eggs of 9-11 days and isolation of virus was done for haemagglutination (HA) and haemagglutination inhibition (HI) test and to identify pathotype of virus by intracerebral pathogenicity index (ICPI) test to determine the virulence of virus. The Genotype-XIII NDV was confirmed by F gene sequence and whole genome sequence.

Results:

During the study mortality due to ND was recorded in 13 layer flocks in spite of routine vaccination, which usually contain Genotype-II strain of virus. The mortality was observed as high as above 50% with an average of 21.21%. The susceptible age for disease was found to be 6-14 weeks. The duration of mortality observed was 23 days. The disease resulted in a significant reduction in body weight, feed intake and drop in egg production. Majority of the outbreaks appeared during extremely hot months of April to June. Greenish diarrhoea was frequently seen in birds that survived early in infection. Mortality continued for 2-3 weeks and reduced with appearance of torticollis. Gross lesions were characterized by multifocal to diffuse hemorrhages around proventricular glands, necrotic (diphtheritic) haemorrhagic ulcers throughout the intestine, disseminated multiple foci of necrosis and pin-point hemorrhages in the spleen parenchyma. The microscopic lesions include focal to diffuse hemorrhages, diffuse infiltration of mononuclear cells, necrosis, and degeneration in visceral organs. All the 13 farm samples (n=13) resulted in death of all the embryos following incubation up to 72 h post-inoculation. All the 13 allantois fluids from field samples along with F and R2B vaccine sample were found positive for HA activity, which was further confirmed by HI using known NDV serum. The values of ICPI were 2.0 which were indicative of velogenic nature of the field NDV strain.

Conclusion:

The study indicated that presently available live and attenuated vaccines which include Genotype-II NDV have failed in protecting the flocks against Genotype-XIII and resulted in outbreaks with mortality above 50%. ICPI score of 2.0 confirmed that the present outbreaks were due to Genotype-XIII NDV, which is velogenic in nature.

Adaptation and growth kinetics study of an Indian isolate of virulent duck enteritis virus in Vero cells

Duck virus enteritis, also known as duck plague, is a viral infection of ducks caused by duck enteritis virus (DEV). The control of the disease is mainly done by vaccination with chicken embryo adapted live virus that is known to be poorly immunogenic and elicits only partial protection. Further, the embryo propagated vaccine virus pose a threat of harboring other infectious agents. Seeing these limitations, the present study reports for the first time regarding propagation and adaptation of a virulent Indian isolate of duck enteritis virus in Vero cell line. In this study isolation of an outbreak virus from Kerala state was done in chicken embryo fibroblast cell culture (CEF). Then adapted the DEV isolate in the Vero cell line. The characteristic cytopathic effects (CPE) of clumping and fusion of Vero cells were observed starting from the 7th passage onwards. The presence of the virus and its multiplication in Vero cells was confirmed by detection of viral specific DNA and antigen by using polymerase chain reaction (PCR) and indirect immuno fluorescent assay (IIFA), respectively. PCR detection of DEV using self designed primers for US4 (gD) and UL30 (DNA Polymerase) gene has been reported for the in the present study. The kinetics of DEV in Vero cells revealed a maximum infectivity titer of 10(5.6) TCID 50/ml after 48hr of viral infection. Compared to chicken embryo adapted DVE vaccine virus, the Vero cell culture system is free from other infectious agents. So it will be a good candidate for cultivation and propagation of duck enteritis virus vaccine strain. Further research studies are suggested to explore the feasibility of utilizing this Vero cell culture adapted DEV isolate for developing an attenuated vaccine virus against duck virus enteritis.