An experimental nasal spray with a broad-spectrum flu antibody is effective against many different flu strains. Such a spray would provide a quick way to prevent flu infections in the future, not only during annual control but also in the event of an outbreak with a dangerous new flu virus. The antibodies can catch the viruses in the nasal cavity as soon as they enter.
Researchers from the Dutch Leyden Laboratories and Harvard University in Boston (USA) published the results on Wednesday Science Translational Medicine. The drug protected against infection in mice and monkeys, and in the first human trials it proved safe.
In the Netherlands, around 4,700 people die every year from the effects of flu, worldwide this is almost 650,000. Vaccines must be adapted every year to changing virus variants and often have only a moderate effect. On average they protect against 30 percent against infection and 41 percent against hospitalization due to fluaccording to the Dutch Society of General Practitioners. In addition, new influenza variants from animals, such as bird flu, pose a risk of a new pandemic. For years, scientists have therefore been looking for products that provide broad and rapid protection, without specifically targeting the circulating strain.
The researchers found such a broadly effective antibody: CR9114. This is aimed at a part of the surface protein hemagglutinin (H), which is the same in many flu virus variants. A flu virus attaches to the host cells with this protein.
There are several subtypes of H, the first three occur in human influenza viruses. The antibody in the spray recognized both human and animal flu viruses in laboratory tests. The antibody can therefore potentially protect against new variants of seasonal flu and unexpected new strains that jump from animals. For example, scientists have feared for years that the bird flu virus H5N1, which is now also circulating in wild mammals and dairy cattle, will one day adapt in such a way that it can circulate between people.
Antibodies remained active for hours
The biggest advantage of administration through the nose is that the antibodies are precisely where the flu virus enters. The antibodies remained active in high concentrations in the nasal mucosa for hours. This is a major improvement compared to the usual administration via an injection or infusion. The amount of antibodies that reach the nasal mucosa is very low.
The 143 healthy subjects who participated in the study tolerated the nasal spray well in various tested doses. Spraying twice a day kept the concentration high enough during the day.
The most convincing evidence came from the monkey tests. Monkeys given the spray and then exposed to the H1N1 flu virus had much lower virus levels and recovered more quickly than untreated animals.
Follow-up studies with larger groups of test subjects must now investigate how well this experimental drug protects people against flu infections, illness and against the transmission of various flu viruses.
In addition to the high concentrations of antibodies in the nose, a nasal spray has even more advantages, the authors write. It is easy to administer at home and can therefore be rolled out more quickly in the early stages of an outbreak. Moreover, it can save costs: antibodies made in the lab are expensive – targeted administration requires less of the drug than via an infusion.
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