Complex sentence: Translation of the positive single stranded RNA occurs at the endoplasmic reticulum; the RNA is translated into a polyprotein which is then cleaved by NS2B-N23, viral proteases, to produce mature proteins.
Split into simpler sentences: Translation of the positive single stranded RNA occurs at the endoplasmic reticulum. The RNA is translated into a polyprotein which is then cleaved by NS2B-N23, viral proteases, to produce mature proteins.