Respiratory
syncytial virus (RSV) was
first isolated in 1956 by Morris and co-workers who named it
“chimpanzee coryza agent”.
Shortly thereafter, Chanock and co-workers
confirmed that the agent was able to cause respiratory illness in
humans.
Respiratory syncytial virus measures from 121 to 300 nm.
It
has an RNA genome, and like all members of the paramyxovirus family,
the envelop exhibits spokes of glycoprotein.
RSV is of worldwide
distribution, and primary infection occurs in the very young.
Visit:
Measles
In the initial
pulmonary Infection there is a lymphocytic peribronchiolar infiltrate
with some edema of the bronchial walls.
Image Link
Necrosis of the cells lining
the bronchioles can be seen.
Subsequently there is a proliferative
response of the bronchial epithelium.
The lumen of the small airways
becomes narrowed because of sloughing of necrotic epithelium and an
increase in mucin secretion.
Obstruction of airflow occurs,
resulting in hyperinflation and trapping of air.
Complete bronchiolar
obstruction may lead to atelectasis.
In severe cases there is a
prominent interstitial alveolar infiltrate accompanied by edema.
Other
manifestations of RSV infection include otitis media, meningitis,
myelitis, and
myocarditis.
|
The histopathology of fatal
untreated human respiratory syncytial virus infection.Mod
Pathol. 2006 Nov 24;
The pathology of
respiratory syncytial virus (RSV) infection was evaluated 1 day
after an outpatient diagnosis of RSV in a child who died in a
motor vehicle accident. We then identified 11 children with
bronchiolitis from the Vanderbilt University autopsy log between
1925 and 1959 who met criteria for possible RSV infection in the
preintensivist era. Their tissue was re-embedded and evaluated by
routine hematoxylin and eosin and PAS staining and immunostaining
with RSV-specific antibodies. Tissue from three cases was
immunostain-positive for RSV antigen and was examined in detail.
Small bronchiole epithelium was circumferentially infected, but
basal cells were spared. Both type 1 and 2 alveolar pneumocytes
were also infected. Although, not possible for archival cases,
tissue from the index case was evaluated by immunostaining with
antibodies to define the cellular components of the inflammatory
response. Inflammatory infiltrates were centered on bronchial and
pulmonary arterioles and consisted of primarily CD69+ monocytes,
CD3+ double-negative T cells, CD8+ T cells, and neutrophils. The
neutrophil distribution was predominantly between arterioles and
airways, while the mononuclear cell distribution was in both
airways and lung parenchyma. Most inflammatory cells were
concentrated submuscular to the airway, but many cells traversed
the smooth muscle into the airway epithelium and lumen. Airway
obstruction was a prominent feature in all cases attributed to
epithelial and inflammatory cell debris mixed with fibrin, mucus,
and edema, and compounded by compression from hyperplastic
lymphoid follicles. These findings inform our understanding of RSV
pathogenesis and may facilitate the development of new approaches
for prevention and treatment. |
|