SYDNEY: Australian researchers and their international colleagues discovered another pathway the COVID-19 virus uses to get into human cells, which may explain the high infection rate of the virus comparing to other similar viruses.

It was already known to researchers that the SARS-CoV-2 virus, which causes COVID-19 symptoms uses ACE2 receptor on human cells as a doorway to get in by binding its spike protein to the receptor.

In two studies released on Wednesday, researchers from the University of Queensland (UQ) in Australia and their colleagues in Europe found the virus can also use another receptor, called neuropilin to enter human cells.

“We now know that in addition to the already known ACE2 receptor, the spike binds to a second receptor on the host cells called neuropilin,” co-researcher Prof. Brett Collins from UQ’s Institute for Molecular Bioscience said.

“We used X-ray crystallography to see the structure of proteins at the atomic level and visualise the binding sites at a spectacular level of detail.”

The fact that antibodies blocking the neuropilin receptor NRP1 are able to block infection by 40 percent strongly suggested that this pathway is key for the virus’ infectivity, according to the researcher.

NRP1 is found on a variety of human cells, which could explain why SARS-CoV-2 virus can also affect human brain cells, with the long-term consequences are not yet known, according to co-researcher Prof. Frederic Meunier from UQ’s Queensland Brain Institute.

“The discovery that NRP1 binds to Spike opens the door to in-depth research into the virus’ neurotropism, its ability to infect nerve tissue, as well as new therapeutic avenues,” Meunier said.