TY - JOUR
T1 - Vaccinia Virus Glycoproteins A33, A34, and B5 Form a Complex for Efficient Endoplasmic Reticulum to trans-Golgi Network Transport
AU - Monticelli, Stephanie R.
AU - Earley, Amalia K.
AU - Stone, Raychel
AU - Norbury, Christopher C.
AU - Ward, Brian M.
N1 - Funding Information:
We thank Bernard Moss for providing vΔA34R and vTF7-3. We also thank Catherine Berlot for providing constructs containing the C and N terminus of YFP and Jay Hooper for providing the A33VACV MAb-10F10. The following reagent was obtained through BEI Resources, NIAIID, NIH: polyclonal anti-vaccinia virus (WR) A33R protein, (antiserum, Rabbit), NR-628. This work was supported in part by NIH grants AI067391 and AI117105. S.R.M. was supported by award number T32AI118689 from the National Institute of Allergy and Infectious Diseases.
Funding Information:
We thank Bernard Moss for providing v?A34R and vTF7-3. We also thank Catherine Berlot for providing constructs containing the C and N terminus of YFP and Jay Hooper for providing the A33VACV MAb-10F10. The following reagent was obtained through BEI Resources, NIAIID, NIH: polyclonal anti-vaccinia virus (WR) A33R protein, (antiserum, Rabbit), NR-628. This work was supported in part by NIH grants AI067391 and AI117105. S.R.M. was supported by award number T32AI118689 from the National Institute of Allergy and Infectious Diseases.
Publisher Copyright:
Copyright © 2020 American Society for Microbiology. All Rights Reserved.
PY - 2020/4/1
Y1 - 2020/4/1
N2 - Orthopoxviruses produce two, antigenically distinct, infectious enveloped virions termed intracellular mature virions and extracellular virions. Extracellular virions are required for cell-to-cell spread and pathogenesis. Specific to the extracellular virion membrane, glycoproteins A33, A34, and B5 are highly conserved among orthopoxviruses and have roles during extracellular virion formation and subsequent infection. B5 is dependent on an interaction with either A33 or A34 for localization to the site of intracellular envelopment and incorporation into the envelope of released extracellular virions. In this report we show that an interaction between A33 and A34 can be detected in infected cells. Furthermore, we show that a three-protein complex between A33, A34, and B5 forms in the endoplasmic reticulum (ER) that disassociates post ER export. Finally, immunofluorescence reveals that coexpression of all three glycoproteins results in their localization to a juxtanuclear region that is presumably the site of intracellular envelopment. These results demonstrate the existence of two previously unidentified interactions: one between A33 and A34 and another simultaneous interaction between all three of the glycoproteins. Furthermore, these results indicate that interactions among A33, A34, and B5 are vital for proper intracellular trafficking and subcellular localization. IMPORTANCE The secondary intracellular envelopment of poxviruses at the transGolgi network to release infectious extracellular virus (EV) is essential for their spread and pathogenesis. Viral glycoproteins A33, A34, and B5 are critical for the efficient production of infectious EV and interactions among these proteins are important for their localization and incorporation into the outer extracellular virion membrane. We have uncovered a novel interaction between glycoproteins A33 and A34. Furthermore, we show that B5 can interact with the A33-A34 complex. Our analysis indicates that the three-protein complex has a role in ER exit and proper localization of the three glycoproteins to the intracellular site of wrapping. These results show that a complex set of interactions occur in the secretory pathway of infected cells to ensure proper glycoprotein trafficking and envelope content, which is important for the release of infectious poxvirus virions.
AB - Orthopoxviruses produce two, antigenically distinct, infectious enveloped virions termed intracellular mature virions and extracellular virions. Extracellular virions are required for cell-to-cell spread and pathogenesis. Specific to the extracellular virion membrane, glycoproteins A33, A34, and B5 are highly conserved among orthopoxviruses and have roles during extracellular virion formation and subsequent infection. B5 is dependent on an interaction with either A33 or A34 for localization to the site of intracellular envelopment and incorporation into the envelope of released extracellular virions. In this report we show that an interaction between A33 and A34 can be detected in infected cells. Furthermore, we show that a three-protein complex between A33, A34, and B5 forms in the endoplasmic reticulum (ER) that disassociates post ER export. Finally, immunofluorescence reveals that coexpression of all three glycoproteins results in their localization to a juxtanuclear region that is presumably the site of intracellular envelopment. These results demonstrate the existence of two previously unidentified interactions: one between A33 and A34 and another simultaneous interaction between all three of the glycoproteins. Furthermore, these results indicate that interactions among A33, A34, and B5 are vital for proper intracellular trafficking and subcellular localization. IMPORTANCE The secondary intracellular envelopment of poxviruses at the transGolgi network to release infectious extracellular virus (EV) is essential for their spread and pathogenesis. Viral glycoproteins A33, A34, and B5 are critical for the efficient production of infectious EV and interactions among these proteins are important for their localization and incorporation into the outer extracellular virion membrane. We have uncovered a novel interaction between glycoproteins A33 and A34. Furthermore, we show that B5 can interact with the A33-A34 complex. Our analysis indicates that the three-protein complex has a role in ER exit and proper localization of the three glycoproteins to the intracellular site of wrapping. These results show that a complex set of interactions occur in the secretory pathway of infected cells to ensure proper glycoprotein trafficking and envelope content, which is important for the release of infectious poxvirus virions.
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U2 - 10.1128/JVI.02155-19
DO - 10.1128/JVI.02155-19
M3 - Article
C2 - 31941777
AN - SCOPUS:85082094113
SN - 0022-538X
VL - 94
JO - Journal of virology
JF - Journal of virology
IS - 7
M1 - e0215519
ER -