Antibody drugs show promise for treating bird flu and HIV

Researchers are increasingly developing antibody therapies to treat infectious diseases. Treatments are being developed to reduce the severity of infections such as avian influenza and treat chronic diseases such as HIV. Synthetic antibodies could also make vaccines against diseases such as COVID-19 more effective.

Antibodies are part of the immune system's defense against infection. Scientists produce synthetic versions by combining mouse B cells and human cell lines. Majority approved antibody drugs intended for the treatment of cancer and autoimmune diseases.

Monoclonal antibodies are also widely used in antiviral therapy to treat severe Ebola infections. respiratory syncytial virus (RSV) and the COVID-19 virus SARS-CoV-2, says Ronghong Zhou, who studies immune responses at the University of Hong Kong. But past efforts to develop antiviral drugs against bird flu have not been as successful because the virus undergoes mutations that make treatments less effective, he adds. Antibody preparations against COVID-19 for the same reason, they became less effective over time.

Treatment of bird flu

For bird flu H5N1, Zhou and his colleagues developed an antibody that has two targets: the stalk region of proteins on the surface of the virus and receptors on human cells. In experiments on cells, they found that the antibody neutralized multiple live strains of the avian influenza virus and was superior to a model monoclonal antibody that targets only one specific antigen in preventing viral particles from attaching to or entering cells. Their results suggest that simultaneously targeting the viral stem and host receptors “is a good strategy to improve antibody efficacy,” says Zhou, who was among the teams presenting their findings in this area at the Pandemic Research Alliance International Symposium in Melbourne last week. But it is still unclear how long the protection will last and whether antibody treatment could cause the virus to mutate to allow it to evade the immune system.

Xiang Hong, a medical student at Columbia University in New York, is also part of the team using anti-H5N1 antibodies. He says he and his colleagues are developing a group of monoclonal antibodies that target multiple parts of the H5N1 virus to track how it evolves over time and identify potential treatments that could target multiple variants of the virus.

Helping hand

Antibodies can also improve the effectiveness of other treatments such as vaccines, which need to be updated because most viruses mutate frequently as they evolve.

Zhiwei Chen, an immunology researcher at the University of Hong Kong, says antibodies that can bind to highly conserved parts of SARS-CoV-2 could help vaccines remain effective even as the virus mutates. Chen and his team identified several areas on the surface of SARS-CoV-2 particles that do not change when the virus mutates. They also found that several antibodies targeting these highly conserved regions were effective in neutralizing a variety of coronaviruses, including SARS-CoV-1, which causes severe acute respiratory syndrome, SARS-CoV-2 variants, and some coronaviruses found in pangolins and bats.