To investigate which hairpin structures within the 5′ untranslated region of hepatitis C virus (HCV) are necessary for cap-independent translation, mutants were constructed that lack one or more hairpin structures. Here we demonstrate, by constructing precisely defined hairpin deletion mutants, that with the exception of the most 5′ located hairpin structure, which on deletion shows an increase on translation, each of the predicted hairpins is found to be essential for cap-independent translation. In addition, we demonstrate that HCV 5′UTR driven translation is stimulated by poliovirus 2Apro co-expression.
