Metapneumovirus (taxid:162387)

VIRION

Enveloped, spherical. Diameter from about 150 nm.

GENOME

Negative-stranded RNA linear genome, about 13 kb in size. Encodes for eight proteins.

GENE EXPRESSION

The viral RNA dependent RNA polymerase binds the encapsidated genome at the leader region, then sequentially transcribes each genes by recognizing start and stop signals flanking viral genes. mRNAs are capped and polyadenylated by the L protein during synthesis.

ENZYMES

• RNA-dependent RNA polymerase [L]
• Mononega-type capping
  • RNA TPase, GTase, N7 Mtase, 2'O Mtase [L]

REPLICATION

CYTOPLASMIC

1. Virus attaches to host cell surface receptors through F and G glycoproteins.
2. Fusion with the plasma membrane; ribonucleocapsid is released in the cytoplasm.
3. Sequential transcription, viral mRNAs are capped and polyadenylated in the cytoplasm.
4. Replication presumably starts when enough nucleoprotein is present to encapsidate neo-synthetized antigenomes and genomes.
5. the ribonucleocapsid interacts with the matrix protein under the plasma membrane and buds via the ESCRT complex, releasing the virion.

Host-virus interaction

Inhibition of host Interferon induction

The G protein plays a role in inhibition of RIG-I antiviral signaling

The M2-2 protein plays a role in inhibition of MAVS antiviral signaling