Bunyaviridae nonstructural S proteins

Bunyaviridae nonstructural S proteins (NSs) are synthesized by viral DNA/RNA and do not play a role in the replication or the viral protein coating.^[1] The nonstructural S segment (NSs) created by Bunyaviridae virus family, are able to interact with the human immune system, in order to increase their replication in infected cells.^[2] Understanding this mechanism can have global health impacts.^[3]

Inhibition pathways

Within the Bunyaviridae virus family, specifically phlebovirus genus, there has been multiple pathways of the inhibition of the immune response.^[3] NSs proteins are able to interact with interferon (INF) pathways, but the mechanism varies from virus to virus.^[4] The NSs protein in different viruses have been shown to differ in amino acid sequence by up to 85%.^[5]

Rift Valley Fever Virus (RVFV)

Further information: Rift Valley fever

NSs protein is distributed throughout the cytoplasm and nucleus of the RVFV-infected cell. The protein created fiber-like substances within the nucleus.^[3] NSs in RVFV to the SAP30 region of DNA in the nucleus of the cell, which is an important promotor region of INF-b.^[6] Many other NSs proteins in the Bunyaviridae virus family do not function in this same way.^[5]

Severe Fever with Thrombocytopenia Syndrome Virus (SFTSV)

Further information: Severe fever with thrombocytopenia syndrome

Although the exact target of the SFTSV is unknown, many believe that the virus attacks human hemopoietic cells.^[7] It has been shown that upstream molecules of INFs are unchanged in infected cells, such as MAVS, TRAF6 and TRAF3.^[7] This suggests that INFs are still being produced, but they have no effect and are undetectable in people's blood serum.^[6] The NSs protein in SFTSV has been shown to interfere with TBK1 which is needed in the activation of both IRF and NF-κB pathways.^[7]

Uukuniemi virus (UUKV)

Further information: Uukuniemi virus

UUKV is a non-human pathogen that still creates a NSs protein.^[5] The NSs protein has only been shown to weakly interact with the 40s subunit of ribosomes and MAVS.^[8][9][10]

Arumowot virus (AMTV)

AMTV is another non-human pathogen and its NSs protein is quickly degraded by proteasomes, and therefore doesn't cause infection in humans.^[11]