Study shows how viruses escape the immune system

Scientists from the University of Otago have gained a deeper understanding of how viruses work and escape the immune system. The team is presently using this finding to find out more about the COVID-19 pandemic.

The new study particularly analyzed the Oryctes rhinoceros nudivirus, or OrNV, virus—a crucial biocontrol agent against the coconut rhinoceros beetle. This beetle is considered a devastating pest for oil palm and coconut trees that grow in the Pacific Islands and Southeast Asia.

The study was headed by Dr Mihnea Bostina and PhD student Sai Velamoor from the Department of Microbiology and Immunology and Otago Micro and Nano Imaging, Electron Microscopy.

At the University of Otago, the researchers discovered that a “decoy” strategy is used by the virus to escape the immune system. This discovery is a small step in an attempt to have a better understanding of the infectious disease, explained Dr Bostina.

The team is currently using the same method to examine the modifications in SARS-CoV-2-infected cells. SARS-CoV-2 is the coronavirus that is responsible for causing COVID-19.

We have used the same technique to investigate changes in cells infected with SARS-CoV-2 and are continuing work in this area.”

Dr Mihnea Bostina, Department of Microbiology and Immunology, University of Otago

Dr Bostina explained that viruses replicating and assembling within the nucleus have evolved unique strategies to alter the landscape of the nucleus for their advantage. The researchers employed electron microscopy to analyze cellular modifications that take place during nudivirus infection and identified a special mechanism for how the virus operates.

Our study revealed that the virus acquires a membrane inside the nucleus of the infected cell and it gets fully equipped to infect new cells at this precise location. This is in contrast with other enveloped viruses—like coronavirus, which is also an enveloped virus—which derive their membranes from other cellular compartments.”

Sai Velamoor, PhD, Department of Microbiology and Immunology, University of Otago

Velamoor continued, “After it gets fully assembled, the virus uses a clever tactic of passing through different environments, packed inside various membrane structures until it gets released at the cellular membrane.”

Ms Velamoor further stated that this kind of approach indicates that several viruses discharged by the infected cells will be covered in a cellular membrane while moving within the infected organism.

This means they will be missed by the immune system and they can use this membrane decoy to penetrate any other type of cells, without the need of a virus specific receptor. It shows for the very first time a clever strategy available to insect viruses. It will be interesting to find in what measure other types of viruses—like the ones infecting humans - are also capable of carrying out a similar process.”

Sai Velamoor, PhD, Department of Microbiology and Immunology, University of Otago

According to Dr Bostina, the study shows another way through which viruses can hijack the infected cells, and thus alerts investigators to the innovative mechanism of viral transmission.

“Viruses will never cease to amaze us with their indefatigable arsenal of tricks. Only by studying them can we be prepared to adequately respond when they infect us,” Dr Bostina concluded.