Study: Antibodies Found to Protect Against Influenza B Virus

Investigators have identified 2 antibodies that protected mice against lethal doses of influenza B virus, which may potentially form the basis for a broad-spectrum flu drug, according to a new study published in Immunity.

Nearly all influenza viruses can be classified into either group A or group B. Tamiflu, the most widely used flu medication, is approved to treat both kinds but is less effective for influenza B, according to the study.

Influenza B is the less common of the 2 forms of the virus and usually shows up later in the flu season; however, children are particularly vulnerable to influenza B. During the 2019-2020 flu season, 187 children in the United States died of the flu, with nearly two-thirds of them from influenza B.

During the same flu season, between 24,000 to 62,000 adults died of influenza in the United States, but only one-quarter of adult deaths were due to influenza B.

Previous research from the investigators centered on an antibody known as 1G01. This antibody protected mice from influenza by jamming a viral enzyme known as neuraminidase.

Both influenza A and B use this enzyme to cut themselves free from cells so they can infect more cells. When this enzyme does not work properly, it cannot infect more cells. According to the previous research, that antibody protected against a wide range of influenza A virus and some influenza B viruses.

For the current study, investigators identified 2 antibodies, 1G05 and 2E01, that potentially inhibit all neuraminidases from a diverse set of 9 influenza B viruses. Investigators also found that the antibodies protected the mice against a lethal dose of influenza B.

Researchers infected groups of 5 mice with influenza B, then treated them 3 days later with either 1G05, 2E01, or a placebo. Four of the 5 mice treated with 1G05 survived and all of the mice treated with 2E01 survived. All 5 mice treated with the placebo died, according to the current study.

"There's a piece of the antibodies that gets down deep into the enzyme's active site and prevents it from cutting by interfering at multiple spots…It is hard to see how you could mutate this site in such a way that the antibodies no longer interfere but the site still functions. It's really a no-win situation for the virus, which is good for us," Daved Fremont, PhD, professor of pathology and immunology at Washington University, said in a press release.

Due to the complexities of the antibodies, it would be especially hard for the virus to develop drug resistance to both of them at once, according to the study. Investigators hope to continue their research into developing a universal flu vaccine.

Reference:

Antibodies protect against wide range of influenza B virus strains [News Release] September 24, 2020. St. Louis, MO. https://www.eurekalert.org/pub_releases/2020-09/wuso-apa092220.php. Accessed September 24, 2020