Fig. 2.

Viral open reading frames (ORFs) and mutations in primer or probe regions.

A Four open reading frames (ORFs) in the viral genome are indicated for encoding viral structural or nonstructural proteins. B–E Mutations have been found in primer and probe regions in various countries and regions. As indicated, most mutations occur in the N protein region, and the efficiency of primers and probes against the N protein coding region will be affected by these mutations. Specific point mutations are indicated in primer or probe regions used in various countries, and these mutations may hamper the detection efficiency of RT-PCR kits and cause false-negative results. Therefore, for the detection of newly occurring mutated variants of the SARS-CoV-2 virus, updating specific primers and probes is essential for the reliability of the kits. E envelope protein, F forward primer, N nucleocapsid protein; ORF open reading frame, P probe, R reverse primer, RdRp RNA-dependent RNA polymerase.