A release from the university said the Finnish researchers had developed a molecule that has the ability to inactivate the coronavirus spike protein and offers effective short-term protection against the virus.
It said that cell cultures in a petri dish and animal studies have shown that the TriSb92 molecule protects against infection for “at least eight hours even in cases of high exposure risk” and is effective immediately after its administration.
“TriSb92 potently neutralizes SARS-CoV-2 and its variants of concern, including delta and omicron. Intranasal administration of a modest dose of TriSb92 (5 or 50 micrograms) as early as eight hours before the challenge with SARS-CoV-2 B.1.351 efficiently protected mice from infection,” the study’s authors wrote. “The target epitope of TriSb92 was defined by cryo-EM, which revealed triggering of a conformational shift in the Spike trimer rather than competition for ACE2 binding as the molecular basis of its strong inhibitory action.”
“Our results highlight the potential of intranasal inhibitors in protecting susceptible individuals from SARS-CoV-2 infection, and describe a novel type of inhibitor that could be of use in addressing the challenge posed by the omicron variant,” they said.
The group’s findings were released as a preprint late last month but have yet to be peer-reviewed and more research is necessary before it could be used on humans.
“In animal models, nasally administered TriSb92 offered protection against infection in an exposure situation where all unprotected mice were infected,” postdoctoral researcher Anna Makela, the first author of the study, said in a statement.
“Targeting this inhibitory effect of the TriSb92 molecule to a site of the coronavirus spike protein common to all variants of the virus makes it possible to effectively inhibit the ability of all known variants, omicron included, to infect people,” she explained, noting the molecule was able to prevent the spread of SARS, potentially indicating future variants of SARS-CoV-2 or new coronaviruses could be “susceptible to it.”
The nasal spray treatment is not a vaccine for COVID-19 and University of Helsinki’s professor Kalle Saksela – who works in the laboratory with Makela – is involved in the development of a Finnish nasally administered coronavirus vaccine, which is expected to progress to clinical trials in the spring.
The pair emphasized that TriSb92 is “a solution that supplements vaccines.”
“These types of molecules that prevent infections, or antiviral drugs for that matter, cannot substitute for vaccines in protecting the population against the coronavirus disease,” Saksela said.
“Individuals whose immune system does not respond strongly enough to vaccines spring to mind in particular. Having said that, we know that new variants, especially omicron, are capable of circumventing even effective vaccine responses worryingly well. Taken before any kind of social interaction, TriSb92 could be useful to people whose vaccine protection is insufficient for one reason or another. Depending on the epidemic situation, it could also benefit fully vaccinated individuals when administered before any situation associated with a high risk of exposure,” the virologist noted.
Saksela told Gizmodo in an email that the technology is “cheap and highly manufacturable,” but that he doesn’t know how long it might take for the spray to reach clinical trials and whether it would be designated a drug or medical device.