|dc.description.abstract||Ovine IgG, IgM and IgA and antisera specific for these immunoglobulins
were prepared. These reagents were used to estimate immunoglobulin levels
in sheep sera and certain other body fluids including the respiratory
secretions. The results showed that a secretory IgA system existed in
the ovine respiratory tract. Furthermore IgA antibodies to Mycoplasma
ovipneumonia were identified in the lung fluid of a sheep clinically
affected with pulmonary adenomatosis.
IgA antibodies specific for Parainfluenza 3 were demonstrated in the
respiratory secretions of lambs which had been experimentally infected
with the virus.
A large molecular weight non-immunoglobulin substance, which inhibited
Parainfluenza 3 and three other paramyxoviruses, was also identified in
the respiratory secretions of both conventionally reared and specific
pathogen free lambs. It is suggested that in certain reports non-specific
inhibitors present in the nasal secretions of calves may have been confused
with Parainfluenza 3 specific IgA antibody.
Attempts were made to define the protective role of nasal secretion
antibody with vaccination-challenge experiments in specific pathogen free
lambs. It was shown that live Parainfluenza 3 administered intranasally
stimulated comparable serum antibody titres but higher nasal secretion
titres than the same dose of live virus given intramuscularly. Inactivated
virus inoculated without adjuvant by either route stimulated low or undetectable serum titres and no nasal antibody. Immunity to aerosol challenge,
as assessed by viral shedding from the nose and changes in post challenge
antibody titres, was best conferred by intranasal inoculation with live
virus. Hence there was some evidence that the presence of antibody in
the nasal secretions reduced the susceptibility to infection.
In subsequent experiments it was found that intramuscular inoculation
of inactivated Parainfluenza 3 in complete Freund's adjuvant stimulated
high serum and nasal secretion titres, which protected against challenge.
However the nasal secretion antibody was IgG^, which was possibly selectively transferred from serum. This contrasted with the earlier finding
of IgA antibodies in the respiratory secretions after intranasal inoculation of live virus and showed that a second mucous antibody system
existed in the ovine respiratory tract.
Results from an experiment with young colostrum fed lambs indicated
that maternal antibody alone could prevent infection with Parainfluenza 3
virus. This showed that the presence of cell-mediated immunity may not
be essential to prevent sheep becoming infected with this virus. In this
and a subsequent experiment it was demonstrated that colostral IgG passed
into the nasal and lachrymal secretions of young lambs. This finding
supported the earlier suggestion that IgG1 is selectively transferred
from serum into the nasal secretions of young lambs. It is suggested
that the presence of maternal IgG1 antibodies in the respiratory secretions
of newborn suckled lambs could constitute an important defence mechanism
against respiratory infections before local antibody synthesis begins at
about two weeks of age.||en
|dc.publisher||The University of Edinburgh||en
|dc.relation.ispartof||Annexe Thesis Digitisation Project 2016 Block 4||en
|dc.title||Studies on the immune response of the ovine respiratory tract toparainfluenza 3 virus||en
|dc.type||Thesis or Dissertation||en
|dc.type.qualificationname||PhD Doctor of Philosophy||en