Novel Negative Sense Genes in the RNA Genome of Coronaviruses

The coronavirus family consists of lipid-containing envelope viruses that have a single-stranded RNA genome that encodes 25–30 proteins in different viruses by the mechanism of positive-polarity strategy. In addition, extended open reading trnslation frames (ORFs, genes) located in a negative-sense orientation were found in the genomes of coronaviruses. The size of negative-sense genes varies in the range of 150–450 nt, which corresponds to polypeptides encoded by negative-polarity genes (negative gene proteins, NGP) with m. m. 5–30 × 10(3) kDa. Coronaviruses show marked differences from virus to virus in the number of negative genes detected. These negative-sense genes in the coronavirus genome allow this family to be considered as viruses developing an ambisense genome strategy.