The mosquito-borne Zika virus (ZIKV) is one of the most feared viruses for pregnant women. Recent statistics justify this fear: Infants born to mothers infected with ZIKV during pregnancy face a risk of up to 42 percent of developing birth defects, including microcephaly (an abnormally small head and decreased brain volume). What do we know about how ZIKV causes damage to the developing brain? Draw a model to illustrate how the Zika virus genome is used to produce new virions. In your drawing, identify the steps required to replicate the genome and those used to produce mRNA. Also note where mRNAs that are used to produce capsid and envelope proteins are translated.

Verified step by step guidance

1. Step 1: Understand the Zika virus structure and genome. Zika virus (ZIKV) is an RNA virus that contains a single-stranded, positive-sense RNA genome. The genome is enclosed within a capsid and surrounded by an envelope with glycoprotein spikes.
2. Step 2: Virus entry into host cell. The virus enters a host cell (typically a neural progenitor cell in the case of brain development damage) by binding to cell surface receptors and undergoing endocytosis, a process where the cell membrane engulfs the virus, forming a vesicle.
3. Step 3: Release and translation of the viral genome. Once inside the cell, the viral envelope fuses with the vesicle membrane, releasing the RNA genome into the cytoplasm. The host cell's ribosomes then translate the viral RNA into a single polyprotein, which is subsequently cleaved into individual functional viral proteins.
4. Step 4: Replication of the viral genome. The viral RNA-dependent RNA polymerase (RdRp), which is encoded by the viral genome, synthesizes new RNA strands using the original RNA as a template. This replication occurs in replication complexes formed on rearranged cellular membranes.
5. Step 5: Assembly and release of new virions. The newly synthesized viral proteins and RNA genomes are assembled into new virus particles in the cytoplasm. The capsid proteins form the core that encloses the RNA genome, while the envelope proteins are embedded in the membrane derived from the host cell, which forms the new virion's outer layer. These new virions are then released from the cell to infect other cells.