Acta Veterinaria-Beograd, cilt.71, sa.2, ss.170-188, 2021 (SCI-Expanded)
Respiratory syncytial virus (RSV) is an RNA virus that belongs to the Pneumovirus genus
of the Paramyxoviridae family. The aim of this study was to evaluate the expressions of
inducible nitric oxide synthetase (iNOS), CD3 (pan T cells), and CD8 (cytotoxic T cells)
in lamb lungs naturally infected with RSV using immunohistochemistry (IHC). For this
purpose, 100 pneumonic and 10 control lung tissue samples were taken from lambs
slaughtered in the slaughterhouse after macroscopic examination. The streptavidin–
peroxidase method (ABC) was used for IHC staining, and it revealed RSV positivity
in 18 of 100 examined lungs with pneumonia (18%). These positive cases were then
immunostained for iNOS, CD3, and CD8, and compared to controls. In all these cases,
an increase in iNOS expression (100%) was detected, the higher number of CD3+ T
lymphocytes was detected in 14 (78%) cases while CD8+ T lymphocytes were detected
in five (28%) cases, only. Given the increase of iNOS immunoexpression in all RSVpositive
cases and increase in the number of CD3+ T lymphocytes in most cases, it was
concluded that iNOS and CD3+ T lymphocytes play an important role in the immune
response in lamb pneumonia with naturally occurring RSV infection. With this study,
the role of the mentioned markers was evaluated for the first time in lambs naturally
infected with RSV.