Inactivation of Highly Transmissible Livestock and Avian Viruses Including Influenza A and Newcastle Disease Virus for Molecular Diagnostics

Abstract

There is a critical need for an inactivation method that completely inactivates pathogens at the time of sample collection but maintains the nucleic acid quality required for diagnostic PCR testing. This inactivation method is needed to alleviate concerns about transmission potential, reduce shipping complications and cost, and allow testing in lower containment laboratories to improve disease diagnostics by improving turn-around time. This study evaluated a panel of ten surrogate viruses that represent highly pathogenic animal diseases. These results showed that a commercial (PrimeStore®) molecular transport media (PSMTM) completely inactivated all viruses tested by >99.99% as determined by infectivity and serial passage assays. However, detection of viral nucleic acid by qRT-PCR was comparable in PSMTM and control-treated conditions. These results were consistent when viruses were evaluated in the presence of biological material such as sera and cloacal swabs to mimic diagnostic sample conditions for non-avian and avian viruses, respectively. The results of this study may be utilized by diagnostic testing laboratories for highly pathogenic agents affecting animal and human populations. These results may be used to revise guidance for select agent diagnostic testing and shipment of infectious substances.Contribution to the fieldActive surveillance and confirmatory testing efforts are in place to protect animals in the United States from certain highly contagious diseases and to limit financial impacts to consumers and producers when the food supply is disrupted. Confirmatory testing typically utilizes nucleic acid detection to identify active infection. Testing is required to be completed in high containment facilities due to the elevated pathogenicity and impact potential of animal diseases. The requirement for testing in high containment facilities limits the ability for regional and state laboratories to test for Tier 1 select agents. Shipment of diagnostic samples is costly, as well as time and temperature sensitive to avoid deterioration of sample quality needed for testing. These constraints lengthen response time and testing turn-around time. Here, we showed that a commercial (PrimeStore®) molecular transport media (PSMTM) completely inactivated all viruses tested without affecting nucleic acid detection/integrity. These data suggest that highly contagious agents are effectively inactivated by PSMTM without compromising the nucleic acid needed for diagnostic testing. These data provide support that this inactivation method can be utilized during sample collection to reduce constraints in disease diagnostics and in reagent sharing among international laboratories.