Development and clinical application of a novel CRISPR-Cas12a based assay for the detection of African swine fever virus.

Background: As no treatment or effective vaccine for African swine fever virus (ASFV) is currently available, a rapid, highly sensitive diagnostic is urgently needed to curb the spread of ASFV.
Results: Here we designed a novel CRISPR-Cas12a based assay for ASFV detection. To detect different ASFV genotypes, 19 crRNAs were designed to target the conserved p72 gene in ASFV, and several crRNAs with high activity were identified that could be used as alternatives in the event of new ASFV variants. The results showed that the sensitivity of the CRISPR-Cas12a based assay is about ten times higher than either the commercial quantitative PCR (qPCR) kit or the OIE-recommended qPCR. CRISPR-Cas12a based assay could also detect ASFV specifically without cross-reactivity with other important viruses in pigs and various virus genotypes. We also found that longer incubation times increased the detection limits, which could be applied to improve assay outcomes in the detection of weakly positive samples and new ASFV variants. In addition, both the CRISPR-Cas12a based assay and commercial qPCR showed very good consistency.
Conclusions: In summary, the CRISPR-Cas12a based assay offers a feasible approach and a new diagnostic technique for the diagnosis of ASFV, particularly in resource-poor settings.