Veterinary Microbiology

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Browsing Veterinary Microbiology by Subject "adjuvant"

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    COMPARATIVE STUDY OF THE STABILITY AND IMMUNOGENICITY OF INACTIVATED BACTERIN, ALUM PRECIPITATED AND OIL ADJUVANTED HEMORRHAGIC SEPTICEMIA VACCINE
    (2018-06) Hassen, Belay; Dr. Nick Nwankpa; Dr. Bedaso Mammo, Dr. Fufa Daewoo
    Haemorrhagic septicaemia (HS) is the most devastating disease of cattle and buffalo particularly to smallholder farmers where husbandry and preventive practices are poor. Due to the acute nature of the disease and the presence of carrier animals after recovery, vaccination is considered as the only efficient method of controlling the disease. Although alum precipitated vaccine is the most widely used; it has come across drawbacks including poor stability and weak immune response. Oil adjuvanted vaccine on the other hand has been emerging with better stability, longer periods of protection and stronger immune response. Therefore, this experimental study was conducted with the objectives of comparing the stability and immunogenicity of inactivated bacterin (IBV), alum precipitated (APV) and oil adjuvanted (OAV) HS vaccine candidates. To achieve this, Pasteurella multocida B:2 (Ethiopian isolate) was grown on tryptose soy broth (TSB) supplemented with 10% horse serum, inactivated with formalin (0.5%) and the turbidity was standardized to contain 1.5mg antigen/ml. APV was prepared by admixing aluminium potassium sulphate (1%) with the bacterin whereas OAV was prepared by mixing the bacterin with equal volume of Montanide ISA 61 VG. The inactivated culture was used as IBV. The three vaccine formulations were stored at 4ºC and tested for stability (potency and identity) once a month for 5 months. Potency test was conducted on mice while test for identity was conducted using polymerase chain reaction. On the other hand, nine calves were divided into three groups, each group vaccinated with each candidate and boosted on day 28 post primary vaccination. Sera were collected on days 0, 28, 42 and 56 to assess the immune response. The IBV and APV showed retention of stability when stored at 4°C for 30 days. The potency dropped to 0.2 log10 and 0.8 log10 for IBV and APV respectively when storage period was extended to 60 days whereas there was no difference between vaccinated and unvaccinated groups when both formulations were stored for 90 days. OAV retained stability when stored at 4°C for 90 days and potency dropped to 0.6 log10 and 0.2 log10 when storage was extended to 120 and 150 days respectively. Application of indirect hemmaglutination test on sera obtained from calves revealed that OAV induced stronger immune response with peak antibody titre of 3.4 log10 on day 56 while APV induced protective, but, relatively weaker immune response with peak antibody titre of 2.4 log10 on day 56. The IBV induced weak immunity (1.5 log10 on day 56) indicating the need for incorporation of a suitable adjuvant. There was a significant difference in the immune response between the vaccine groups (P<0.05, ANOVA). Therefore, this study revealed the weak stability as well as immunogenicity of the conventionally used alum precipitated vaccine and urges the need to produce oil adjuvanted vaccine for the control of the disease.
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    Evaluation of different adjuvant formulations of inactivated trivalent foot and mouth disease vaccine in cattle
    (Addis Ababa University, 2021) Getu Ayele; Dr. Bedaso Mammo; Dr. Belayneh Getachew
    Foot-and-mouth disease is globally one of the most economically important viral diseases of cloven-hoofed animals that can primarily controlled by vaccination. Selection of the effective adjuvants formulated simultaneously with the antigen in the vaccine is crucial in ensuring the quality of vaccine and the protective effect of the vaccine against FMD. Aluminum hydroxide gel and saponin (AS) is the most used adjuvant, with its shortcoming in short duration and poor immune response in FMD vaccine. Therefore, the present experimental study was undertaken to evaluate different formulation of adjuvants for inactivated trivalent FMD vaccine containing A, O and SAT 2 serotypes in cattle. Additionally, this study was also performed to demonstrate the effect of booster dose administration on immune response. The vaccines were prepared by mixing 10 % of aluminum hydroxide gel, 0.3 % of saponin with the virus suspension. Oil based was prepared with equal volume of virus suspension (50:50). Twenty-nine cattle were classified into five groups, with four experimental groups consisting of six cattle in each group (n=6) and the fifth group is a control group with five cattle (n=5). The experimental cattle were grouped as: AS, AS boosted, oil based and AS + oil. The sera sample were collected on day 0, 7, 14, 21, 28 and 42, their immune response was measured using Solid Phase Competitive Enzyme Linked Immune Sorbent Assay (SPCE). There was a significant difference in the immune response between the adjuvant groups (P<0.05, ANOVA). The results showed that, the antibody level in cattle vaccinated with AS were significantly lower than AS boosted group for serotype A, O and SAT 2, indicating that the need for booster dose. Whereas the antibody response in the AS + oil group was higher followed by oil alone, AS boosted and AS. It can be concluded that oil based and AS with oil induce better antibody response relative to others and they could replace the aluminum hydroxide gel and saponin for FMD vaccine production to control the disease. On different note, challenge test was not successful in this study indicating the need for further research on the virus infectivity.