3.4 Replication of H6N6 subtype AIV in human lung tissue
Lung and bronchus tissues of humans were collected at 12h, 24h, and 48h
post-inoculation of H6N6 viruses, after which they were ground. Their
supernatant was then inoculated in 10-day-old embryonated chicken eggs
and MDCK cells. In the isolation and culture of embryonated chicken
eggs, the virus was detected in the lungs of humans inoculated with
ZZ346, the HA titers on days 3 post-inoculation were 1:8; it was not
observed for ZZ1923 and JX20490 virus. For MDCK isolation, three strains
were not detected. The lung tissue inoculated with ZZ346 strain showed
that lung tissue structure was destroyed, inflammatory cells such as
lymphocytes and monocytes infiltrated in lung interstitial and
bronchiolar mucosal epithelium necrosed and fell off. However, the
obvious pathological changes of lung tissue inoculated with ZZ1923 and
JX20490 virus strain were not observed. But there were no obvious
histopathological changes in bronchial tissue inoculated with three
strains of the H6N6 virus.
The immunohistochemical method was used to detect NP protein of
influenza virus in bronchial and lung inoculated with three strains of
the H6N6 virus. The virus NP protein was detected in alveolar cells of
lung inoculated with ZZ346 virus strain, while was not detected in human
lung tissues of JX20490 and ZZ1923 virus strain (Figure 6 ). NP
protein of influenza virus was not detected in bronchus and bronchioles
inoculated with three strains of H6N6. Our study suggested that the
ZZ346 strain of the H6N6 virus, with binding to avian-like SAα-2,3Gal
and human-like SAα-2,6Gal, was effectively replicated in the human lung
without prior adaptation.