Browsing by Author "Belayneh Getachew"

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    Isolation and Molecular Identification of Newcastle Disease Virus in Chickens and Evaluating the Protective Efficacy of Newcastle Disease Vaccines in Ada’a District, East Shewa, Ethiopia
    (2021-09) Gossaye Bogale; Belayneh Getachew
    Newcastle disease (ND) is the first most economically important endemic viral disease of chickens that has a potential threat to village chickens and commercial poultry farms in Ethiopia. Reports from NVI Sales and Customer service directorate evidenced that customers are complaining against the effectiveness of lentogenic ND vaccines. Therefore, this study was designed to isolate and molecularly identify Newcastle disease virus and to assess the protective efficacy of ND vaccines against the current circulating viruses. The study was carried out from December 2019 to May 2021 in Ada’a district; Bishoftu town and Dhankaka village. A Cross-sectional study method was used to investigate ND in suspected cases and a total of 52 samples were collected for virus isolation and virus gene detection. ND virus was isolated in specific-pathogen-free (SPF) embryonated chicken eggs and virulence of the isolates were determined in vitro and in vivo. The current findings confirmed the circulation of virulent strains of ND virus in the study areas. The isolates were further identified by molecular assay, targeting the amplification of avian paramyxovirus-1 (APMV-1). Vaccine protection efficiency was evaluated in chickens hatched from SPF eggs. The chickens were selected randomly and assigned to five experimental groups. Experiment groups were vaccinated by the lentogenic vaccines (HB1, Lasota, and I-2) produced in the National Veterinary Institute (NVI) using 106.5Embryo infective dose (EID)50 per chicken at day zero (age of 7 days), and boosted at days 14 and 35. Group 1 was vaccinated by HB1 on day zero, revaccinated using Lasota on day 14 and boosted by Lasota on day 35 (HB1-Lasota-Lasota). Similarly, groups 2 - 4 were vaccinated, and boosted as (HB1-I2-I2), (I2-Lasota-Lasota), and (HB1- I2-Lasota) vaccines, respectively while group 5 were unvaccinated and threated as a control group. On day 49 all treatment groups were challenged by ‘Dhankaka’ ND virus isolate with 106.5ELD50 per chicken through occulo-nasal route. The result indicated that chickens in group 1 were induced a protective index of 94%, chickens in groups 2, 3, and 4 were revealed 100% survival while chickens in the unvaccinated group were all dead. Hence, the current ND vaccines produced at NVI induced an immune response against the circulating virulent ND virus using vaccination-boost-boost and challenge protocol in experimental SPF chickens challenge.
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    Isolation, Identification and Seroprevalence of Newcastle Disease Virus in Village Chickens in South West Shewa Ethiopia
    (Debre Zeit, 2009) Belayneh Getachew; Kyule Moses
    A study on seroprevalence, isolation and identification of Newcastle disease virus in village chickens in south west shewa zone was conducted using Enzyme Linked Immunosorbent Assay, Haemagglutination, Haemagglutination inhibition test and real time RT-PCR. A total of 355 chickens from eight kebeles of the study site were used for the study of seroprevalence. The overall seroprevalence of Newcastle disease virus antibodies in the study area was 5.6% (3.2- 8.0% at 95 % CI). Five (62.5%) of the eight kebeles sampled had chickens that were positive for antibodies against NDV. The prevalence in each kebele ranges from 0% to 28.1 % and the highest prevalence (28.1 %) was found at Harbu Kebele which is located just near to the market. The prevalences of chicken's serum antibody in the highland and lowland area were 0.9% and 7.8% respectively. Statistically significant (p<0.05) difference in prevalence of Newcastle disease virus antibodies was found between highland and lowland, local and cross breeds and young and adult chickens. The difference, however, was not statistically significant (p>0.05) for male and female. Much (95%) of the chicken sera do have a percent inhibition value between -104 and 74.33 and a normally distributed figure was found. From Newcastle suspected outbreak cases, six samples were collected from recently dead and sick chickens for isolation and identification of Newcastle disease virus. The result indicated that all the six samples were positive for Haemagglutination and Haemagglutination inhibition tests. But cloacal and tracheal swab samples from 30 apparently healthy chickens revealed that there was no haemagglutinating viral agents. None of the samples can lead to the death of embryo even at the second passage. Subjection of genome extract from allantoic harvest to real time RT-PCR using specific primer for fusion protein cleavage site resulted in amplification of viral genome. Three samples taken from allantoic harvest of outbreak areas were amplified but none was amplified from apparently healthy chicken using real time RT-PCR. This further confirmed that Avian Paramyxovirus type one was isolated and identified from outbreak cases of ND in the study area. The low prevalence to NDV in the study area indicated that the village chickens are highly susceptible to the pathogenic NDV infection. Thus, it is recommended that there should be routine vaccination program in the study area.