RATIONALE:

Influenza A viruses (IAVs) still threaten human health and life. The process of virus infection involves a series of biological regulations, such as signal transduction that may be closely linked with the function of glycoproteins. However, the number and level of glycoproteins is low compared with other proteins in the whole protein pool.

METHODS:

Viruses obtained from chicken embryos were purified by sucrose gradient centrifugation. PNGase F enzyme was then used to remove the glycan modification, followed by two-dimensional electrophoresis (2DE) to separate the hemagglutinin1 (HA1) glycoprotein. In-gel digestion was used to obtain peptides that were detected by MALDI-TOF mass spectrometry.

RESULTS:

Remarkably, we found 5 isoforms of HA1 with the same molecular weight but different isoelectric points. Furthermore, HA1 treatment with PNGase F enzyme changed all but one protein spot from 2DE, indicating that the different HA1 isoforms in 2DE were a result of different glycosylation modifications.

CONCLUSIONS:

The difference in isoelectric point of these HA1 was caused by glycan modification. This method provides a new approach for the study of glycosylation of the proteome for viruses or any other organisms.