Influenza virus infection is a highly communicable acute
respiratory disease that causes significant morbidity and
mortality in young children, immunocompromised patients
and elderly people in annual epidemics and pandemic
outbreaks worldwide (1, 2). Influenza viruses are
classified into three types: A, B and C. The causative agents
for worldwide influenza outbreaks are the type A and B
viruses, both of which express two envelope glycoproteins:
hemagglutinin (H or HA) and neuraminidase (N or NA)
(also known as sialidase).