) ‫أنموذج ( أ ) الخاص برسائل الماجستير و اطاريح الدكتوراة ( اخر شهادة‬
University of Baghdad
College Name
Veterinary Medicine
Department
Unit of Zoonotic Diseases
Full Name as written
in Passport
WAFFAA ABDULELAH AHMED
e-mail
waffaabduleah@yahoo.com
Career
Assistant Lecturer
Master
Lecturer
Assistant Professor
Professor
PhD
Thesis Title
An experimental immunopathological study of cross protection between
Mycobacterium bovis and Brucella abortus
Year
2002
Abstract
A number of criteria have been tackled during the course of our study , the first one is the
evaluation of S19 vaccine which is produced locally to know the potential efficacy in protecting
against the brucellosis disease , the second criterion was investigated by many experiments that
have been carried out to study the degree of similarity in the structural components that comprises
the antigenicity between M.bovis and B. abortus by cross immunization and testing the cross
protection that is conferred by one against the other and finally an attempt was made to derive new
methods to simplify the diagnosis .
The brucellin ( PGB) which is mainly composed of the peptidoglycan proved to be a powerful
trigger for the production of antibodies and delayed type hypersensitivity when applied
intradermally in sensitized experimental animals as confirming .
The infections in these animals , and also done in sheep , goats , calves and heifers , no
negative reaction obtained when using the doses of 10 , 100 , and 200 µg .On the contrary 500 µg
gave wheal and flare even in the skin of non immunized ( control ) animals, it was shown later ,
during the evaluation of S19 vaccine , that there was no skin reaction given by the control animals
of all species ( guinea pigs , sheep , goats , calves and heifers )
These findings form a good base for the sustained potency and specificity of our new product
in the diagnosis of the disease .
The results showed also , that the locally produced vaccine is effective in immunization
whether given to laboratory animals by one or two doses , by installation in the conjuctiva , or
subcutaneous injection and this immunization lasted for up to ten weeks .
The fact that vaccine has proved effective despite that we have reduced the dose ( 8 X10 9
viable cell /ml ) for cattle . A good titers of specific antibodies were obtained up till 23 rd weeks after
vaccination . Another important finding is that locally produced vaccine has given positive results
in animal species other than those specified for , these are sheep , and goats which may pave the
way widely for more studies then after , with the possibility of using one vaccine for different
species instead of the two vaccines currently in use .
The new trend of immunization technique by the conjuctival rout in cattle , this will help in a
comprehensive immunization against brucellosis mainly in buffalo but such technique failed to
immunize sufficiently calves .
Our results , that were obtained by serological methods were re-evaluated by passive
haemagglutination test and found out that they were comparable and the averages of antibodies
titers in guinea pigs were 685.71 after two weeks which rises to 923.57 at tenth week . This is in
accordance with those of serological tests .
On the other hand , the titer averages which were shown after conjunctival immunization , were
higher than those appeared by subcutaneous immunization . These results prove that the local
vaccine is an effective with high efficiency both in experimental animals as well as field animals
) ‫أنموذج ( أ ) الخاص برسائل الماجستير و اطاريح الدكتوراة ( اخر شهادة‬
with no obvious side effect that could be noticed as a result of vaccination .
The novel criterion in our study is dealing with the cross reactions as was investigated by
delayed hypersensitivity skin testing and PHT . The main goal was to verify the cross immunization
between M. bovis and B. abortus which may assist in the diagnosis and immunization . It is
concluded , with no doubt , the presence of cross immunization among the two organisms . As
shown by skin testing , the mean diameter of erythemas was 7.16 mm with brucellin and 6.7 mm
with tuberculin and thickness difference was 1.64 mm with brucellin and 0.93 with tuberculin .
A positive results were also obtained when cross reaction tests were done in sheep as compared
with the negative controls for both the erythemas and skin thickness .
Cross reactions among S19 and PPD , immunized animals were also , confirmed by a more
sensitive PHT especially in guinea pigs immunized with S19 by conjunctival installation . These
animals were either immunized with BCG and tested with brucellin but with lower titers when
immunized with S19 but tested by PPD antigen . Despite that an obvious cross reaction was noticed
between BCG and our brucellin .It was shown that immunization with BCG gave good results .
This vaccine proved to be a specific and non specific immunopotentiator by using serum from S19
conjuctival immunized sheep and tested by PPD and PGB antigens . This suggests the success of
immunization of these animals with S19 vaccine .
As for the results of PHT with the sera of calves and heifers, they also referred to the clear cross
reaction when comparing the averages which result from the reaction with PPD and PGB . This
again may conclude the efficiency of such immunization of calves and heifers .
We should note that our prepared antigens PPD & PGB have sensitized the RBC properly , that
in turn , gave high agglutination titers when tested with the sera of immunized animals which
confirm the cross reactions . From the serological and skin experiment it can be concluded that
shared serological and cellular immune reactions between B.abortus and M.bovis are definite .
Our results sustained by gross and histopathological changes in vaccinated , infected and
vaccinated infected guinea pigs. The vaccinated guinea pigs were infected with hetrologus virulent
bacteria. The appearance of granulomatous lesions in almost all or some organs which were
indicative for tuberculosis , a signal that the strain used in our experiment is of high virulence and it
resisted phagocytosis by macrophages , also appearance of epitheliod cell considered as an
advanced stage of progression of macrophages which have high activity to kill tubercle bacilli . The
same state for brucella strain which causes appearance of many granulomatus lesions on the liver
surface and histologically presence of many focci of granulomatous lesions surrounded by
histological capsule with vacuolar and degenerative changes .
Also the presence of abscesses and casseated material in the site of inoculation in some
vaccinated challenged animals demonstrated the strong immunological response and delayed
hypersensitivity for M.bovis and B.abortus .
Finally the appearance of moderate pathological changes in sustained on the pathological lesion
on one hand and subside of some others on the other hand especially in internal organs in
comparison with infected not vaccinated animals considered a proof for declining level of the mean
of multiplication and dissemination of virulent bacteria due to provokation of cellular immunity. Of
what have been presented we concluded that there was cross reaction & cross protection between
M.bovis and B.abortus .