Viruses use ‘GPS’ to move precisely within insects 

Viruses are expert parasites, having evolved to infect a variety of host species. Some viruses, known as arboviruses, use insects to spread their infections to other hosts, such as humans and animals.

Understanding how these viruses move through insect hosts could provide key insights for blocking their transmission.

Virus movement within insects

A recent study published in the Journal of Virology sheds light on how viruses strategically move within their insect hosts, and how this movement aids in the spread of infection to other animals.

This knowledge is especially important for addressing viruses like Zika , dengue, and West Nile virus, which are transmitted from insects to humans and livestock.

Navigating specific routes

“Viruses that use insects as hosts must navigate specific routes through different insect tissues to complete their life cycles. The routes may differ substantially depending on the life cycle of the virus,” noted the study authors.

“Both insect pathogenic viruses and insect-vectored viruses must navigate through the polarized cells of the midgut epithelium to establish a systemic infection. In addition, insect-vectored viruses must also navigate through the polarized salivary gland epithelium for transmission.”

Tracing the paths of proteins

To investigate viral movement, the researchers used fruit flies as a model to trace the paths of proteins from two different viruses. One virus was insect-specific, while the other could infect both insects and animals, including humans.

By studying these viral proteins, the team gained a better understanding of how they navigate through insect hosts to facilitate transmission .

“Using Drosophila as a model to examine tissue-specific polarized trafficking of these viral envelope proteins, we identified one of the virus-encoded signals and several host proteins associated with regulating the polarized trafficking in the midgut epithelium,” explained the researchers.

Precise movement of viruses

Gary Blissard is a professor at the Boyce Thompson Institute and co-lead author of the study.

“Even when expressed on their own, without the rest of the virus, these proteins moved to precisely the correct locations in the insect cells,” said Professor Blissard.

In the insect’s gut, the viral proteins migrated to the bottom of the cells, positioning themselves to move into the insect’s body cavity. This movement set the stage for the viruses to spread further.

Varying behavior of the viral proteins

In the salivary glands, however, the two viral proteins behaved differently. While the protein from the insect-only virus still moved to the cell's bottom, the protein from the virus capable of infecting animals often shifted to the top of the cells.

This is an ideal location for assembling new virus particles and releasing them into the saliva, ready to infect another animal host.

Guided by “GPS” signals

This precise positioning is critical to the viruses’ life cycles and ability to spread. It’s almost as if the viral proteins have an internal “GPS” guiding them to the right locations within the insect host.

The study revealed that this “GPS” is made up of amino acid sequence signals encoded in the viral proteins themselves.

These signals are recognized by the host insect’s own protein transport systems, which help direct the viral proteins to their target destinations. The researchers also identified parts of the insect's cellular machinery that the viral proteins hijack to reach their final locations.

Disrupting the movement of viruses

This discovery opens the door to potential new strategies for combating virus transmission.

If scientists can find a way to disrupt the viral proteins' GPS or the cellular machinery they rely on, it may be possible to prevent the viruses from reaching or leaving the salivary glands of the insect.

This could effectively block the virus from using the insect as a vector, halting its spread to new hosts.

Broader implications of the study

“Our research highlights the incredible adaptations viruses have evolved to navigate through complex biological systems such as insects,” said Nicolas Buchon, an associate professor at Cornell University ’s Department of Entomology and co-lead author of the study.

“It's a reminder of the continuous evolutionary arms race between viruses and their hosts and the importance of basic research in understanding these intricate biological processes.”

By uncovering the molecular mechanisms behind viral movement within insects, this research paves the way for new approaches to controlling insect-borne diseases .

This knowledge could also have applications in managing agricultural pests, ultimately leading to better public health measures and improved crop protection in the future.

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