Biology Reference
In-Depth Information
Chapter 4
Virus H9N2
Mohamed Rajik, Fatemeh Jahanshiri, Abdul Rahman Omar, Aini Ideris,
Sharifah Syed Hassan, and Khatijah Yusoff
INTRODUCTION
Avian influenza viruses (AIV) cause high morbidity and mortality among the poul-
try worldwide. Their highly mutative nature often results in the emergence of drug
resistant strains, which have the potential of causing a pandemic. The virus has two
immunologically important glycoproteins, hemagglutinin (HA), neuraminidase (NA),
and one ion channel protein M2 which are the most important targets for drug discov-
ery, on its surface. In order to identify a peptide-based virus inhibitor against any of
these surface proteins, a disulfide constrained heptapeptide phage display library was
biopanned against purified AIV sub-type H9N2 virus particles.
After four rounds of panning, four different fusion phages were identifi ed. Among
the four, the phage displaying the peptide NDFRSKT possessed good anti-viral prop-
erties
in vitro
and
in ovo
. Further, this peptide inhibited the hemagglutination activity
of the viruses but showed very little and no effect on neuraminidase and hemolytic
activities respectively. The phage-antibody competition assay proved that the pep-
tide competed with anti-infl uenza H9N2 antibodies for the binding sites. Based on
yeast two-hybrid assay, we observed that the peptide inhibited the viral replication
by interacting with the HA protein and this observation was further confi rmed by co-
immunoprecipitation.
Our fi ndings show that we have successfully identifi ed a novel antiviral peptide
against avian infl uenza virus H9N2 which act by binding with the hemagglutination
protein of the virus. The broad spectrum activity of the peptide molecule against vari-
ous subtypes of the avian and human infl uenza viruses and its comparative effi ciency
against currently available anti-infl uenza drugs are yet to be explored.
Avian infl uenza A viruses (AIV) are enveloped, segmented, and negative-stranded
RNA viruses, that circulate worldwide and cause one of the most serious avian dis-
eases called Bird Flu, with severe economic losses to the poultry industry [1]. They
are divided into different subtypes based on two surface glycoproteins, hemagglutinin
(HA) and neuraminidase (NA). Currently, there are 16 different types of HA and nine
different types of NA circulating among aquatic birds [2]. Although, wild birds and
domestic waterfowls are considered natural reservoirs for all subtypes, they usually
do not show any symptoms of the disease. Domestic birds such as chickens are main
victims of this virus especially of H5, H7, and H9 subtypes. The H9N2 viruses are
