Compare biosynthesis of a + stranded RNA and a - stranded RNA virus.

Verified step by step guidance

1. Identify the type of nucleic acid in the virus: + stranded RNA viruses have RNA that can directly serve as mRNA, while - stranded RNA viruses have RNA that is complementary to mRNA.
2. For + stranded RNA viruses, understand that the viral RNA can be directly translated by the host's ribosomes to produce viral proteins.
3. For - stranded RNA viruses, recognize that the viral RNA must first be transcribed into a complementary + strand by an RNA-dependent RNA polymerase before it can be translated into proteins.
4. Consider the replication process: + stranded RNA viruses often use their RNA as a template to synthesize a complementary - strand, which then serves as a template for producing more + strands.
5. For - stranded RNA viruses, the initial - strand is used to produce a + strand, which then serves as a template for synthesizing new - strands for packaging into new virions.

Key Concepts

RNA Virus Classification

RNA viruses are classified based on their strand orientation: positive-sense (+) RNA viruses have genomes that can be directly translated into proteins, while negative-sense (-) RNA viruses require transcription into a complementary positive strand before translation. This distinction is crucial for understanding their replication mechanisms and the strategies they employ to hijack host cellular machinery.

Biosynthesis Mechanism

The biosynthesis of + stranded RNA viruses involves direct translation of their RNA genome by host ribosomes, leading to the production of viral proteins. In contrast, - stranded RNA viruses must first synthesize a complementary + strand using an RNA-dependent RNA polymerase, which then serves as a template for protein synthesis and replication of the viral genome.

Role of RNA-Dependent RNA Polymerase

RNA-dependent RNA polymerase (RdRp) is an essential enzyme for RNA viruses, particularly for - stranded RNA viruses. It catalyzes the synthesis of a complementary + strand from the - strand genome, enabling the production of viral proteins and replication of the viral genome. Understanding the function of RdRp is vital for developing antiviral strategies targeting these viruses.