Final answer:
Negative-strand RNA viruses contain single-stranded RNA with a sequence that is complementary to mRNA, requiring synthesis of a positive strand before translation can occur. They utilize RNA-dependent RNA polymerase for replication and are a significant human health concern, as is exemplified by viruses such as Influenza and SARS.
Step-by-step explanation:
Negative-strand RNA viruses are a type of RNA virus that house their genetic material as single-strand RNA with a negative polarity, which is complementary to the mRNA. They belong to Group V of the Baltimore classification system. Unlike their positive-strand counterparts, these viruses must first synthesize a positive RNA strand from their genomic RNA using an enzyme called RNA-dependent RNA polymerase (RdRP) before their genetic material can be translated into viral proteins by the host's ribosomes.
During the replication process, the negative RNA strand serves as a template for the production of both mRNA and full-length positive RNA strands. The positive strands are then used as templates to create new negative-strand genomes. This replication strategy distinguishes them from positive-strand RNA viruses, which can have their RNA directly translated by host ribosomes. Notable examples of negative-strand RNA viruses include the Influenza virus and the Severe Acute Respiratory Syndrome (SARS) virus, both of which have significant impacts on human health.