Scientists working with the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, have reported promising results with a noel vaccine for Bovine Respiratory Syncitial Virus (BRSV).
BRSV is one of the most common viral agents involved in the bovine respiratory disease (BRD) complex. A closely related Respiratory Syncitial Virus (RSV), also of the Orthopneumovirus genus, is commonly associated with respiratory disease in humans. RSV infections are estimated to cause more than 250,000 human deaths annually around the world.
The novel vaccine is based on a single, stabilized version of the RSV fusion glycoprotein in its initial conformation, called pre-F. The researchers note that other RSV vaccines have used the final conformation of the same protein, known as post-F.
Using small groups of three- to six-week-old calves in this study, the researchers compared the vaccine based on the pre-F protein with one based on the post-F protein and with a control group injected with a placebo. They injected each treatment group twice, with four weeks between treatments, then challenged the calves with BRSV four weeks after the second treatment.
In this trial, the calves vaccinated with the pre-F protein had more than 100-fold higher levels of neutralizing antibodies than those that received the post-F protein. Four of the five calves in the pre-F group were protected from BRSV viral replication in the upper and lower respiratory tracts. In contrast, BRSV was detected in all calves immunized with either the post-F protein or placebo.
The researchers also note that recombinant subunit-based vaccines, such as the one tested in this trial, do not pose risks associated with live viruses, but do provide an opportunity to generate highly effective and targeted immune responses. They also have potential advantages in terms of ease and speed of manufacturing, quality control of purity, and long term stability.
In their discussion, the report’s authors say a similar approach to vaccine development could result in more effective vaccines to protect against the human form of RSV.
The study report, titled “Protection of calves by a prefusion-stabilized bovine RSV F vaccine” is published in the journal npj Vaccines. The full report is available online.