Refining and Improving BRSV Testing

Background

While not all Bovine Respiratory Disease (BRD) is Bovine Respiratory Syncytial Virus (BRSV), all BRSV is BRD, and it can mean big losses in terms of animal health and production. There are many pathogens that play a role in BRD infections, BRSV plays an important role. Currently, BRSV is diagnosed by looking for specific RNA sequences through PCR. The issue with this method is we are unable to tell the BRSV of disease apart from BRSV from the vaccine which can lead to misdiagnoses. However, genomic sequencing opens to potential to not only tell what is a BRSV infection versus virus in a vaccine, it can also tell regional variation between strains which could help inform how to manage and treat an outbreak more effectively.

Objectives

•  Refine the current methods of diagnosing Bovine Respiratory Syncytial Virus (BRSV) with the ability to detect regional strains, differentiate strains causing disease from the vaccine strains and improve BRSV surveillance.

What they will do

This team will use existing known positive samples ranging from highly positive to borderline, from the Prairie Diagnostic Services Inc. and other labs in western Canada and subject them to two different methods of testing:

• Metagenomic sequencing (nanopore technology) – sequencing the all DNA and RNA from a sample which include BRSV sequences.

• Targeted sequencing – only looking at BRSV

The first method is to evaluate the limits of whole genome testing – how positive of a BRSV sample is needed in order to yield meaningful results. This method is less sensitive but can potentially detect all pathogens in a sample. The second method is less expensive and more sensitive, while it won’t yield a whole genome sequence, the team will be able to test it’s ability to pick out specific genes to yield more information on the particular strain of BRSV that is causing the infection. Samples that are triggering positive results due to vaccination will also be included as to build an internal database so those testing can differentiate between vaccinated animals and those that are infected AND go beyond to report the specific field strain driving the infection.

Implications

Refining how we currently test for BRSV can open many doors for producers. The ability to differentiate between infected and vaccinate animals means producers can vaccinate without worrying about false positives or treating animals that don’t actually need it. Having the ability to go beyond and understand the actual strain of BRSV that is driving infection can inform treatment plans and prevention strategies as well as adds to our base of knowledge for BRD surveillance. Finally, the methodology and learning that comes from this project can be used to improve how we test for other BRD important pathogens.