Determination of Mycoplasma Mycoides Subsp. Mycoides Components That Confer Protection Against Contagious Bovine Pleuropneumonia and Understanding of Immunological Responses
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Date
2016Author
Mwirigi, Martin K
Type
ThesisLanguage
en_USMetadata
Show full item recordAbstract
Contagious Bovine Pleuropneumonia (CBPP) is a severe respiratory disease caused by
Mycoplasma mycoides subsp. mycoides (Mmm) which is widespread in Africa. The main
control option is a live vaccine, with low efficacy and a short duration of immunity.
Development of an efficacious CBPP vaccine requires understanding immunogenicity of
the antigens and protective immune responses. A series of experiments were undertaken
to establish whether components of the Mmm, including whole cell lysate, membrane
proteins and capsular polysaccharide can induce protection. Three separate experiments
were conducted to evaluate the capacities to protect and detect possible correlations with
immunological responses. The first experiment examined the efficacy of inactivated
vaccine formulations: heat inactivated and formalin inactivated Mmm were compared
with the live attenuated vaccine. Second experiment involved evaluation of a vaccine
formulation generated from the Mmm membrane protein components. The third
experiment entailed vaccination of cattle with a conjugated Capsular Polysaccharide and
subsequent experimental challenge with the infective Afadé strain. Disease outcome was
analysed through clinical, pathological observations and immunological parameters. The
protection levels were 31%, 80.8% and 74.1% for the formalin-inactivated, heatinactivated
and live attenuated preparations, respectively. Conjugated capsular
polysaccharide produced a protection rate of 57%. The vaccine also elicited CPS-specific
antibody responses with the same or a higher titer than animals vaccinated with the live
vaccine. Interestingly, the animals immunised with membrane proteins had enhanced
disease. These findings indicate that; i) low doses of heat-inactivated Mmm can offer
protection to a level similar to the current live attenuated (T1/44) vaccine formulation, ii)
vaccination with membrane proteins revealed enhanced inflammatory reactions after
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challenge iii) capsular polysaccharide antigens conjugated to a protein is immunogenic
and induces protective immunity in cattle and iv) high immunoglobulin (IgG and IgM)
responses can be raised against the carbohydrate component of the CPS-based
glycoconjugate. Future development for a vaccine against CBPP needs to focus on
understanding of immunological reactions that leads to pathological conditions and those
that lead to protection especially the innate immune response.
Publisher
University of Nairobi
Rights
Attribution-NonCommercial-NoDerivs 3.0 United StatesUsage Rights
http://creativecommons.org/licenses/by-nc-nd/3.0/us/Collections
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