Abstract
The influenza virus surface glycoprotein hemagglutinin (HA) is responsible for viral attachment to sialic acid-containing host cell receptors and it facilitates the initial stage of viral infection. In the present study, we isolated an RNA aptamer specific to the glycosylated receptor-binding domain of the HA protein (gHA1) after 12 cycles of the systematic evolution of ligands by exponential enrichment procedure (SELEX), and we then investigated if the selected aptamer suppresses viral infection in host cells. Nitrocellulose filter binding and enzyme-linked immunosorbent assay (ELISA) experiments revealed that 1 RNA aptamer, HA12-16, bound specifically to the gHA1 protein. Cell viability assay showed that the HA12-16 RNA aptamer suppressed viral infection in host cells by enhancing cell viability. Immunofluorescence microscopic analysis further demonstrated that the HA12-16 RNA aptamer suppresses viral attachment to host cells by neutralizing the receptor-binding site of influenza virus HA. These results indicate that the isolated RNA aptamer can be developed as an antiviral reagent against influenza through appropriate therapeutic formulation.
Highlights
Avian influenza is an acute viral respiratory disease that causes severe damage to the poultry industry because it results in high mortality
Recent global outbreaks of avian influenza caused by the avian influenza virus (AIV) poses a serious public health threat because of potential transmission among humans
Influenza viruses belong to the family Orthomyxoviridae and are further divided into subtypes according to the combination of 2 major immunogenic surface glycoprotein components: hemagglutinin (HA) and neuraminidase (NA), which are present on the surface of viral envelopes [1,2]
Summary
Avian influenza is an acute viral respiratory disease that causes severe damage to the poultry industry because it results in high mortality. HA is a homotrimeric transmembrane protein with a globular head and a stem region that are both exposed to the outside of the membrane [5]. These regions contain N-linked oligosaccharides [6], which have been known to affect the functional properties of HA [7,8]. The recombinant HA1 subunit, expressed and purified from bacteria, induces an immune response against the influenza virus in humans [13] and is sufficient for screening antiviral RNA aptamers [14]. The recombinant HA protein, which retains glycosylation, has been expressed and produced in a baculovirus/insect cell system, which exhibited enhanced HA inhibition and virus neutralization [15]
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