EFFICACYAND IMMUNOGENICITY OF EIMERIA TENELLA APICAL MEMBRANE ANTIGEN-1 (EtAMA1) DNA VACCINE AGAINST EIMERIA TENELLA INFECTION IN BROILER CHICKENS
EFFICACYAND IMMUNOGENICITY OF EIMERIA TENELLA APICAL MEMBRANE ANTIGEN-1 (EtAMA1) DNA VACCINE AGAINST EIMERIA TENELLA INFECTION IN BROILER CHICKENS
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Date
2021-04
Authors
HAMBESHA, Paul Terkende
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Abstract
Apical membrane antigen-1 (AMA1), being a micronemal transmembrane protein of
apicomplexan parasites, is secreted by the microneme organelles onto the parasite surface
during host cells invasions. In this study, the performances, immune response,
haematological, gross, and histopathological changes were assessed to evaluate the level of
protective immunity of the Eimeria tenella apical membrane antigen-1 (EtAMA1) DNA
vaccine in broiler chickens challenged with two strains of E. tenella oocysts. Eighty (80)
day-old broiler chicks divided into four groups (G1, G2, G3, and G4) were used for the
study. Chicks in G1 were unvaccinated unchallenged and G2 unvaccinated challenged.
Chicks in G3 and G4 were intramuscularly vaccinated with a DNA vaccine, a construct of
EtAMA1 Houghton strain, at 14, and21daysofage. Seven days after the booster vaccination,
G2 and G3 were challenged with a local isolate of E. tenella while G4 was challenged with
Houghton strain of E. tenella. The chickens were observed for clinical signs, body weight
gain, survival rate, oocyst count, lesion scores, and anticoccidial index. Blood samples were
collected on day 14, 21, 28, and 35 of age for haematology and sera harvested for
determination of IgY and interferongamma (IFN-γ) concentration. Also, at 7 days post
challenge, caeca collected from sacrificed birds were observed grossly for lesions, weighed
and fixed in 10 % neutral buffered formalin for histopathology. Clinical signs associated
with coccidiosis which include depression, dullness, somnolence, reduced feed in-take,
bloody faeces, and soiled vent were mild in vaccinated challenged chickens, but very
severe in unvaccinated challenged chickens.There was significant (p < 0.05)reduction in the
oocyst output and increased weight gain in vaccinated challenged birds (G3 and G4)
compared to unvaccinated challenged birds (G2). Haematology revealed significantly (p <
0.05) decreased PCV, Hb, total protein, MCV, MCH, and MCHC in unvaccinated
challenged chickens when compared to vaccinated chickens. The heterophil/lymphocyte
ratio was significantly higher in unvaccinated challenged birds. Significantly high (p <
0.05) levels of serum IgY and IFN-γ concentrations were observed in vaccinated chickens.
Histopathological examination showed desquamation and necrosis of mucosal glands in
unvaccinated challenged birds. The results showed that DNA vaccine encoding EtAMA1
improved performance and elicited an increase in serum levels ofIgY and IFN-γ thus, could
provide some level of immunity against caecal coccidiosis of not just that of the
homologous strain but also of a heterologous strain from another geographical area.
Description
A THESIS SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES,
AHMADU BELLO UNIVERSITY ZARIA, NIGERIA IN PARTIAL
FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF THE
DEGREE OF MASTER OF SCIENCE IN AVIAN MEDICINE
DEPARTMENT OF VETERINARY MEDICINE,
FACULTY OF VETERINARY MEDICINE,
AHMADU BELLO UNIVERSITY,
ZARIA, NIGERIA
Keywords
EFFICACY AND IMMUNOGENCITY,, EIMERIA TENELLA,, APICAL MEMBRANE ANTIGEN-1 (EtAMA1),, DNA VACCINE,, EIMERIA TENELLA INFECTION,, BROILER CHICKENS