March 22, 2017

New RSV Vaccine Technology Shows Promise in Cattle, Humans

A new investigational vaccine has shown promise in protecting cattle from respiratory syncytial virus infection, according to a recent study.
By Nicola M. Parry, BVSc, MRCVS, MSc, DACVP, ELS
A new investigational vaccine has shown promise in protecting cattle from respiratory syncytial virus (RSV) infection, according to a recent study by scientists at the Vaccine Research Center of the National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health, Bethesda, Maryland.
 
Using a similar approach to vaccine development could also help produce more effective vaccines to protect against the human form of the virus, the authors say. Results of the study were published online in npj Vaccines.
 
In an interview with American VeterinarianTM, Peter D. Kwong, PhD, chief of the Structural Biology Section at the NIAID Vaccine Research Center, highlighted the significant economic impact that bovine RSV places on the cattle industry. RSV is responsible for the majority of respiratory disease in cattle, at an estimated cost of $1 billion per year.
 
He added that human RSV also poses a substantial burden. In the United States, an estimated 57,000 children under 5 years of age and more than 100,000 adults are hospitalized each year due to RSV infection, costing billions of dollars.
 
In the case of both calves and infants, however, vaccines need to overcome the difficulties associated with both activation of very young immune systems and the inhibitory effect of maternal antibodies. Bovine RSV vaccines continue to suffer from issues of effectiveness, and no licensed human RSV vaccine is currently available.
 
Therefore, development of safe and effective RSV vaccines for cattle and humans continues to be a priority. “The most potently neutralizing RSV antibodies identified thus far target the pre-fusion (pre-F) form of the RSV fusion (F) glycoprotein,” the authors say.
 
Dr. Kwong and his team, therefore, conducted a study to test whether a structure-based fusion (F) glycoprotein vaccine, called DS2, could succeed where other vaccines have failed. This novel vaccine contains a single, structurally engineered RSV protein that led to high levels of neutralizing antibodies in mice. 
 
The researchers tested the investigational vaccine in calves 3 to 6 weeks of age and found that it succeeded in protecting them from RSV infection.
 
“When challenged with a heterologous bovine RSV, the DS2-immunized animals showed no virus in nasal secretions nor in respiratory tract samples,” said Dr. Kwong. “In contrast, bovine RSV was found in all placebo-immunized animals.”
 
These results suggest that the DS2 vaccine could help to reduce the incidence of bovine RSV, Dr. Kwong stated. And because bovine RSV is also a good model system for how an equivalent human RSV F vaccine might work, he added that an equivalent human RSV F vaccine might also be efficacious.
 
Indeed, Dr. Kwong noted that the NIAID recently began testing a similar vaccine construct, called DS-Cav1, in a phase 1 human trial.
 
“Both the DS2-bovine vaccine and the DS-Cav1-human RSV vaccine are examples of structure-based vaccines, which use atomic-level design to fix immunogen conformation,” he explained. “It is hoped that structure-based design can deliver successful vaccine against other viruses, such as HIV-1, for which conventional vaccinology has failed.” 
 
 
Dr. Parry graduated from the University of Liverpool, England in 1997 and is a board-certified veterinary pathologist. After 13 years working in academia, she founded Midwest Veterinary Pathology, LLC where she now works as a private consultant. She is passionate about veterinary education and serves on the Indiana Veterinary Medical Association’s Continuing Education Committee. She regularly writes continuing education articles for veterinary organizations and journals, and she has also served on the American College of Veterinary Pathologists’ Examination Committee and Education Committee.

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