New Insights Into Andes Hantavirus Interaction with Human Cells for Future Treatment

Earlier this year, an outbreak of the Andes hantavirus on a cruise ship resulted in three passenger fatalities and 13 other infections, sparking urgent concerns regarding the lack of approved vaccines and treatments for this dangerous virus. New research published in the journal Nature by scientists from Albert Einstein College of Medicine, in collaboration with Institut Pasteur and LSU Health Shreveport, sheds light on how the virus attaches to human cells, which may lead to the development of effective therapies against the Andes virus and its relatives.

Understanding the Andes Hantavirus

The Andes hantavirus belongs to a broader family of viruses primarily carried by rodents and known for causing severe and often fatal diseases, including hantavirus pulmonary syndrome. This respiratory illness can escalate quickly, often leading to respiratory failure. Infections typically occur when individuals inhale airborne particles from the excrement and saliva of infected rodents. Notably, of the more than 20 known hantaviruses, Andes virus uniquely possesses the ability to spread from person to person, particularly through prolonged close contact.

Research by the team at Albert Einstein College centered on how the Andes virus's spike protein interacts with a protein on human cells known as PCDH1, which acts as a gateway for the virus to infiltrate and multiply within human cells. In earlier work, researchers identified PCDH1 as the receptor utilized by the Andes virus for cell entry, yet the mechanism of attachment remained a mystery until now.

Decoding the Infection Mechanism

The breakthrough study reveals that the Andes virus spike protein is constructed from four identical protein units, forming a square shape. This unique configuration contrasts sharply with other viruses, like SARS-CoV-2, whose spike proteins are built from three units arranged in a triangle, each capable of engaging a receptor independently.

Through advanced cryo-electron microscopy, researchers captured detailed structural images of the Andes virus spike in tandem with PCDH1, leading to an important discovery: a specific pocket or groove at the virus's core allows the receptor to embed itself deeply into the spike. This design limits antibody access, making it challenging for the human immune system to combat the virus effectively.

The Antibody Challenge

Notably, while researching various antibodies collected from human hantavirus patients, the team observed that some of these antibodies were able to bind to the spike protein but could not fit into the groove as PCDH1 does. This finding indicates a sophisticated method by which the Andes virus evades immune response. Though antibodies attempt to make contact with the virus, they ultimately fail to bind as effectively as the receptor does.

Kartik Chandran, one of the study’s corresponding authors, emphasizes this molecular intricacy, noting that the virus's mutations allow it to evade destruction by antibodies while still maintaining its ability to connect with PCDH1, akin to a fine-tuned “friend-or-foe” identification system.

Implications for Future Research and Treatments

The study also highlights potential avenues for therapeutic development. While human antibodies are restricted by size and structure, scientists could engineer compounds that mimic the slender architecture of PCDH1, which may block the receptor's access and hinder the virus entry. This approach may serve as a blueprint for innovative antiviral treatments capable of targeting Andes virus and its close counterpart, the Sin Nombre virus found in North America.

Dr. Pablo Guardado-Calvo of the Institut Pasteur perceives this research as monumental not just for Andes hantavirus but for the broader family of high-consequence viruses. By understanding receptor interactions on a molecular level, the research paves the way for the formulation of effective protective strategies against these pathogens.