This colorized transmission electron micrograph shows a single Nipah virus particle (center, colorized green) budding from the surface of an infected cell (pink). The virus’s surface glycoproteins are labeled using immunogold labeling, where gold particles (yellow) bind to antibodies targeting a specific viral antigen or epitope. This technique helps researchers visualize the antibodies and confirm the virus type in the image. (Photo by: NIH-NIAID/Image Point FR/BSIP/Universal Images Group via Getty Images)
BSIP/Universal Images Group via Getty Images
Nipah and Hendra viruses rank among the deadliest, with a mortality rate of 40 to 75 percent in those infected. These viruses belong to the henipavirus family, with Nipah mainly present in South and Southeast Asia and Hendra primarily found in Australia. Despite the risk they pose for a pandemic, no approved treatments exist for these infections.
The viruses originate in fruit bats, their natural hosts, and spread to other animals before reaching humans. Nipah virus outbreaks are linked to contaminated food, infected livestock, and human-to-human transmission, whereas Hendra virus often spreads from bats to horses and occasionally to humans. Though outbreaks are infrequent, both viruses can cause severe pneumonia and encephalitis, making them top priorities for the World Health Organization as emerging pathogens.
Why Two Antibodies?
Nipah and Hendra viruses share many surface proteins, allowing the same antibodies to identify both viruses. The new treatment employs a novel strategy, combining two antibodies that target distinct viral proteins. One antibody interferes with the receptor binding protein, preventing the virus from attaching to human cells, while the other targets the fusion protein, blocking the virus from entering the cell.
Traditional antibody therapies often focus on a single target, but a mutation can enable the virus to evade treatment. By targeting two critical proteins, this antibody cocktail complicates the development of resistance and remains effective against both Nipah and Hendra viruses. This combination protected animals from deadly infections and was effective against viral mutations that individual antibodies could not counter.
The antibodies recognize stable regions of the proteins across different Nipah and Hendra virus strains, potentially maintaining their protective effect as new variants arise.
Animal Protection
In tests with hamsters infected with lethal doses of Nipah virus, animals that received either antibody survived the infection. The combined antibody treatment offered full protection even when administered after infection had started.
Laboratory tests showed similar results, with the cocktail neutralizing viruses from both major Nipah strains and Hendra virus, demonstrating its broad effectiveness across the henipavirus family.
Beyond Nipah and Hendra
Viruses are constantly evolving, and treatments targeting a single aspect can lose efficacy as mutations build up. Combining antibodies that target different conserved regions offers a more sustainable approach to preventing resistance while ensuring protection.
Similar approaches are being explored for other quickly evolving viruses. Future antibody treatments may increasingly focus on targeting multiple essential viral components rather than a single vulnerable site. This strategy could bolster treatments for both newly emerging viruses and persistent challenges in existing ones.
