GALVESTON, Texas — Scientists at the University of Texas Medical Branch at Galveston and the Scripps Research Institute in La Jolla, Calif., have received a five-year, $4.8 million grant from the National Institute of Allergy and Infectious Diseases to produce a new, safer vaccine candidate for Junin virus, a deadly Argentine hemorrhagic fever pathogen identified as a potential bioterrorism threat.
Junin is one of several closely related South American viruses naturally found in different species of rodents. The viruses don’t harm the animals, but infectious particles shed in rodent urine can produce severe hemorrhagic fever in humans who encounter them, leading to fatality rates as high as 30 percent and long-term neurological disorders among survivors.
A vaccine for Junin — a weakened strain of the virus that produces immunity without causing any disease — already exists and is being manufactured in Argentina. But issues related to its production, including the use of locally derived bovine serum that could spread highly contagious foot and mouth disease and lack of regulatory documentation required for the drug’s approval, have prevented the vaccine’s adoption in the United States.
An FDA-approved Junin vaccine would make research on the virus safer and more practical — and could also open the door to experiments that would shed light on related pathogens, including Lassa fever virus. In addition, it could prove essential if Junin virus were to be released by bioterrorists.
“This is a spinoff of a small developmental project sponsored by the Western Regional Center of Excellence in Biodefense and Infectious Diseases, in which we developed the techniques to produce both the original vaccine strain and the virulent strain using recombinant genetics— essentially assembling viruses gene by gene and artificially re-generating the viruses in the cell culture,” said UTMB associate professor of Pathology and Director of the Preclinical Studies Core at the Galveston National Laboratory, Slobodan Paessler. “In this project we want to better characterize this vaccine strain that we generated and examine it very closely, which will allow us to create a recombinant vaccine candidate that is safer and potentially more effective than the original vaccine. In addition, we want to improve our understanding concerning the stability of such vaccines in general.”
Accomplishing that will require the resources of UTMB’s biosafety level 4 laboratories, which allow researchers to work safely with highly pathogenic viruses like Junin. And because the genes of Junin viruses are coded in mutation-prone RNA rather than DNA, identifying variations in the recombinant vaccine is critical to quality control — which is where the Scripps team comes in.
“Our co-principal investigator at Scripps, Juan Carlos de la Torre, is an expert in viral genetics and very good at what is called ‘deep sequencing’ of genetic samples, which allows him to pick out very low-level viral populations that would be missed by more conventional methods,” Paessler said. “With RNA viruses there’s always a lot of variation, and they’re going to be performing deep sequencing and data analysis so we can see what the changes are, and reconstruct them and test them for safety. It’s very exciting to be able to work with a collaborator with such powerful capabilities.
“Of course, we are also absolutely thrilled to receive this prestigious award from NIAID — this kind of support has been essential in helping us build a community of highly skilled scientists in Galveston.”