I lie pulmonary imnuinopalliology of parainfluenza type 3 (I'l V-3) infection in sheep was investigated
firstly by isolating ttic virus from field cases of sliccp pneumonia, secondly by experimentally reproducing the
disease with the isolated vims and finally try studying changes in lymphocytes subsets and alveolar
macrophages, induced by HI V-3 in vivo and in vitro.Three ovine virus isolates (270-7, 390-10 and 430-7) were obtained and characterised, as l'IV-3.
according to virus morphology, transmission electron microscopy (I HM); cylopalhic cll'ccl (CI'H);
hacmagglutination, of guinea pig erythrocytes; physicochcmical properties; serological crossrcaclivity with
anliscra raised against l'IV-3; and reactivity with monoclonal antibodies to l'IV-3 structural proteins, that
crossrcact with human and bovine strains.flic ability of the virus to induce respiratory disease was investigated by experimental inoculation of
ovine l'IV-3 isolate, 270-7 in colostrum deprived lambs Clinical, pathological, bacteriological and virological
studies were carried out on days 2. 3, 3 and 7 post infection (p i ), l itis I'l V-3 ovine strain was able to induce
clinical disease, llistopathological findings were interstitial pneumonia with hyperplasia of bronchiolar
associated lymphoid tissue (HALT), degenerative bronchiolar epithelium with lymphocyte inlillration, areas of
atelectasis and increased alveolar septa thickness due to proliferation of type II pncmnocytcs, lymphocytes,
macrophages and later to Itbrosis. lire large number of lymphocytes, particularly on days 5 and 7 pi,
combined with the minimal to moderate cytolvsis of antigen bearing cells suggests that l'IV-3-induced
pulmonary disease has an inuuunopathological component. l'IV-3 particles were detected more frequently in
bronchiolar epithelium cells than in alveolar septal cell This was correlated with changes of these cell
populations in lung lesions, delected by iminunohistochemislry.Alter 7 days p i . virus-induced changes in the leukocyte composition of the lungs were detected using
a panel of rnAbs (o ovine lymphocytes and macrophages. Changes in lung tissue were detected by
inununohistology and changes in lungwash llnid (LWH) bv llowcylomctry. Association lieI ween lung cells and
virus particles was investigated by double immunoslaining. The differential cell count of LWIf from l'IV-3
infected animals was characterised by a significant increase (pet).03) in lymphocytes and neutrophils.
Lymphocy te phcnolyping showed a significant decrease (pet).05) of C'1711 cells, a significant increase (p<0.05)
oT CDK1 cells and a significant inversion (pcO.OO I) or the (171 '/COS1 ratio. Immunoslaining of I'l V-3 infected
lung sections showed a remarkable increase of lymphocy tes, particularly in HALT, and most cells were CD81.
flic number of macrophages increased in peribronchial and alveolar septa and some were positive lor I'l V-3
particles.Cultures of peripheral blood monocylc-dcrivcd macrophages (MUMf) and alveolar macrophages
(AMf) were established, file ability of l'IV-3 lo inlccl these cells was studied by CI'H, and virus particle
immtmoslaining. Viral replication was detected by TliM and scanning electron microscopy (SBM). l'IV-3
induced lytic CI'H'w ith inlracyloplastnic eosinophilic inclusion Ixidics and syncy tia formation. I'HM revealed
virus budding al the cell membrane, lilamcntous cytoplasmic inclusions and clusters of pleomorphic viral
particles in the extracellular space.es in the extracellular space.
flic expression of MIIC class I and MIIC class II molecules, which is associated willt antigen
presenting function, was studied alter in vitro inlccl ion of MUM and AM with I'l V-3. UK and IX) Ml It.' class
II expression was moderately high (60-80%) on noninl'cclcd fresh monocytes and AM but, allcr 3 days in
culture the expression of this molecules was dramatically reduced lo 5%. Stimulation with y-llrN was able to
promptly restore MIIC class II expression in cultured noninfcclcd MUM arid AM. This did not occur alter I'l V3
infection. The expression of MIIC class I molecules was not significantly all'cctcd (p>0,05) by culture or
I 'I V-3 infection.flic phagocytic activity of macrophages lor ITfC-lnbcllcd/nnlibody-coalcd sheep red blood
cclls(SRUC) alter I'l V-3 infection decreased significantly (p< ().()3) alter .3 days p i
