Veterinary Public Health

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Browsing Veterinary Public Health by Subject "Adjuvant"

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    Determination of the shelf life of inactivated fowl cholera vaccine developed from local isolates of Pasteurella multocida
    (Addis Abeba University, 2022) Dawit Dufera; Dr.Fufa Dawo; Dr.Takele Abayneh
    Fowl cholera (FC) is caused by Pasteurella multocida (P. multocida) and is a highly contagious disease that causes very high economic losses to the poultry industry around the world through high mortality, weight loss, low production of hatching eggs, reduction of fertility and carcass condemnation. Vaccination is one of the most widely used preventative strategies in the world to minimize illness prevalence and incidence of diseases including FC. Although NVI started to produce the killed FC vaccine in 2019, the shelf-life of the vaccine at 2-8 0C storage conditions was not determined; this was the objective of the current study. The shelf life was determined based on an indirect approach i.e. through evaluation of immune response to the vaccine stored at different time points as a direct approach to determining antigen content was not practicable. Hence, a total of 175 layer chickens (8 weeks old Bovans Brown) hatched and grown at Research and Development Laboratory, National Veterinary Institute (NVI) were used to determine the shelf life of the formalin-inactivated alum adjuvant FC vaccines. The vaccine's shelf life was determined using primary and secondary (booster) dose immunization of chicken with formalin-inactivated alum adjuvanted FC vaccine stored at 2- 8 0C for two weeks, three, six, nine, twelve, eighteen and twenty-four months. Blood was collected from each chicken before primary immunization (at day zero), and on days 21 and 35 after primary vaccination to determine serum antibody levels by Indirect Enzyme-Linked Immunosorbent Assay (I-ELISA). All chickens used for this study indicated a low cut-off OD value of 0.2 and that they were free from serum antibody response against Avian P. multocida before immunization (at day 0). The level of chicken serum antibody (IgG) titre was significantly increased after 3 weeks of the first immunization. After two weeks of the second vaccination, the titre substantially increased in all chickens. Antibody titre was increased within the group from primary vaccination to secondary (booster) vaccination. However, antibody titre was decreased among the groups with advancing storage time of the vaccine. As a result, formalin-inactivated alum adjuvant FC vaccine-induced antibody response while being kept at the standard recommended condition of storage for up to twenty-four months.
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    Isolation, Molecular Identification and Vaccine Trial of Mycoplasma Gallisepticum in Ethiopia
    (Addis Ababauniversity, 2015-06) Bekele, Legesse; Mamo, Badaso (Professor)
    The study and entire laboratory works ware conducted from December 2014 to April 2015 in National Veterinary Institute, Bishoftu, Ethiopia. A total of 120(20 chickens from four farms and 40 backyard chickens from commercial farms and local markets respectively) were used for the study. The chickens were slaughtered at national veterinary institute postmortem room and tracheal, air sac and lung samples were collected from slaughtered chickens. Isolation and molecular characterization of Mycoplasma gallisepticum strains was done based on standard recommended methods. And the objective of this study is to identify local strains and to undertake molecular characterization of Mycoplasma gallisepticum circulating in the chicken population of farms in Bishoftu. This can help to device strategies in controlling the disease mainly through developing more effective vaccine which will replace the currently being imported Mycoplasma gallisepticum vaccines by some farmers. Then propagation was undertaken using appropriate culturing procedure. The mycoplasmal DNA was extracted and polymerase chain reaction was conducted for amplification of Mycoplasma gallisepticum Mgc2 gene. Amplified deoxyribonucleic acid fragments were analyzed by conventional 2% agarose gel electrophoresis incorporating appropriate size markers, followed by examination under Ultra violate light. The Polymerase chain reaction product for Mycoplasma gallisepticum was 185 bp. A number of 3 pooled (from 30 chickens) mycoplasma isolates were recovered from chickens in 2 farms and from back yard chickens in Bishoftu. Of these, 3 Mg isolates were identified using growth inhibition and rapid serum agglutination tests. Among six isolates (3 pooled and 3 lyophilized National veterinary institute isolates), (50%) or 3 samples were found strong positive and (50%) or 3 samples were weak positive to Mycoplasma gallisepticum as they gave 185 bp products, similar to the positive control when visualized electrophoretical analysis. Finally oil based Inactivated Mycoplasma gallisepticum vaccine was produced in suitable clean and secure accommodation, well separated from production facilities of National Veterinary institute. In this study, formaldehyde inactivated Montanide ISA70 based Mycoplasma gallisepticum vaccine from the Polymerase chain reaction confirmed positive from Samuel local isolate of National Veterinary Institute was prepared and evaluated in chickens. The amount of immune antigen per 0.5ml of the dose was 10 7 Colony forming units of the bacteria. At the age of 16 weeks, the chickens were randomly divided into three groups (A, B and C), each having twenty birds. Each bird of group B was vaccinated group of imported- live vaccine with 30μl dropped in the eye and each bird of group C was inoculated with 0.5 ml indigenous or trial vaccine subcutaneously at mid neck region and group A was used as a control. xiv After challenge test, among non-vaccinated chickens ( control or group A) 2 chickens were died (10 %), thicken and cloudy appearance of the air sac showed 18 (90% ), 2 chickens were not showed thickened and cloudy air sack ( 10% ). Although among vaccinated group (inactivated vaccine or group C) all chickens did not show clinical signs or post mortem changes (100 %). From attenuated imported live vaccine (group B) no clinical signs or post mortem changes was observed (100 %). It was concluded that oil based Mycoplasma gallisepticum vaccine induces protective level of anti Mycoplasma gallisepticum antibodies in chickens. Keywords: Adjuvant, Chickens, Inactivated vaccine, Mycoplasma gallisepticum, and polymerase chain reaction