Scientists Isolate Antibodies From Vaccinated Blood as Potential Measles Treatment

Scientists have isolated four potent antibodies from the blood of a 56-year-old vaccinated woman that block the measles virus. The antibodies were identified in a study published Thursday in the journal Cell Host & Microbe. The work could lead to a treatment for people exposed to the highly contagious respiratory disease.

Measles was declared eliminated in the United States in 2000 after a safe and effective vaccine became available in the 1960s. Sporadic cases and outbreaks have occurred since then. However dropping vaccination rates have led to large outbreaks in multiple states and the country is approaching a point where the virus could spread freely again.

New treatments would be particularly useful for immunocompromised individuals and babies under one year old who cannot receive the vaccine. The antibodies target two key proteins on the virus surface. One protein allows the virus to attach to cells while the other enables it to fuse with and enter them.

In tests on rodents the experimental antibodies reduced virus levels in the lungs when administered one to two days after infection. The approach is not intended to replace vaccination. A spokesperson for the research team said the treatment would always be more expensive than the vaccine and prevention remains the priority for public health.

The study examined antibodies that bind to the H protein which helps the virus latch onto cells and the F protein which changes shape to allow cell entry. Two of the selected antibodies lock the F protein in place while the other two block the H protein's attachment function.

Further testing is required to determine whether the antibodies are safe and effective in humans. If successful the therapy could be given after exposure similar to antivenom following a snakebite or used preventively like the antibody treatment given to protect infants from RSV.

Scientists decoded the three-dimensional structures of both the viral proteins and the antibodies to identify the most effective candidates.

For decades there was little incentive to develop such treatments because the live weakened measles vaccine generates strong immunity. A biochemist who has studied the measles virus for 40 years and was not involved in the research described the structural details as impressive and potentially relevant to understanding other viruses.

A pediatrician and director of a vaccine education center at a children's hospital noted that any antibody treatment would need to be administered shortly after exposure before symptoms appear. Immune globulin derived from people with immunity is already available as an option.

The pediatrician emphasized that prevention through vaccination has been effective in controlling the disease. An associate professor of biology at a university who studies infectious disease evolution said the characterization of antibody responses is valuable for understanding immune complexity.

The professor raised the possibility that monoclonal antibodies could exert selective pressure on the virus potentially affecting future vaccine effectiveness though this remains a theoretical concern.