Anthony Schmitt, PhD
- Postdoctoral training in molecular virology with Dr. Robert A. Lamb, Northwestern University, Evanston, IL
- Ph.D. in Biological Chemistry with Dr. Kevin McEntee, UCLA School of Medicine
- B.S. in Honors Biology, University of Illinois, Urbana
Assembly and Budding of Paramyxovirus Particles
particles are vehicles that transmit infection from cell to cell and from host
to host. For viruses that are membrane-enveloped, particles are formed by
budding. Buds emerge from selected sites on cellular membranes, then pinch off
and are released. Prior to budding, different viral components assemble
together in a coordinated way and concentrate at budding sites. This assembly
process allows for the release of particles that are likely to be infectious,
as they are densely packed with viral proteins and contain viral genomes. My
research group studies assembly and budding of the paramyxoviruses. These enveloped RNA viruses include a number
of important human and animal pathogens that impact human health and agriculture worldwide, including measles virus, mumps virus,
respiratory syncytial virus, Newcastle disease virus, and the newly emerged
Nipah and Hendra viruses.
Mumps virus has caused a resurgence of disease in developed countries in recent years, mainly due to lack of compliance with vaccination protocols. Many of the molecular aspects of mumps virus replication, including mechanisms of virus assembly, remain poorly understood. We have recently developed and optimized procedures that allow for efficient production of mumps virus-like particles (VLPs) in cultured mammalian cells. The VLPs bud from transfected cells and resemble authentic virions when viewed with an electron microscope. Interestingly, we found that cooperation among different mumps virus proteins was necessary for efficient VLP production. We are currently investigating how mumps virus proteins are able to cooperate with one another during particle formation, and why such cooperation during VLP assembly is required for mumps virus, but not for many of the other paramyxoviruses. In addition, we are examining the roles of host factors in mumps virus budding.
Parainfluenza virus 5 (PIV5) is a model paramyxovirus that is closely related to mumps virus. A reverse genetics system has been established for PIV5, allowing recombinant viruses to be generated from cloned DNA. By manipulating the infectious DNA clone, we are able to make targeted changes to the viral RNA genome and test what effects these changes have on virus assembly and budding. Using this approach, we defined a region of the viral nucleocapsid (NP) protein that mediates interaction with the viral matrix (M) protein during virus assembly. Recombinant viruses with defects in M-NP protein interaction acquired different types of adaptive mutations that provide new insights into mechanisms of virus spread. We have also identified host factors that bind to the PIV5 M protein. Angiomotin-like 1 (AmotL1) and ubiquitin bind to PIV5 M protein and facilitate particle formation, while 14-3-3 protein binds to PIV5 M protein in a way that is detrimental to the virus assembly function of M protein. We are currently working to understand the mechanisms by which these host factors influence PIV5 budding.
The Henipaviruses, Nipah virus and Hendra virus, are newly-emerged paramyxoviruses that cause deadly infections in humans. These zoonotic viruses readily infect domesticated pigs and horses, and spread to workers who come into contact with infected animals. We have identified a number of host factors that bind to the Nipah and Hendra virus M proteins, and are working to develop new strategies for the inhibition of Henipavirus replication, by targeting M protein-host protein binding interfaces. These studies are supported by the Middle Atlantic Regional Center of Excellence for Biodefense and Emerging Infectious Disease Research (MARCE).
Harrison, M.S., Schmitt, P.T., Pei, Z., and Schmitt, A.P. (2012). Role of ubiquitin in PIV5 particle formation. J. Virol., In press.
Pei, Z., Harrison, M.S., and Schmitt, A.P. (2011). PIV5 M protein interaction with host protein 14-3-3 negatively affects virus particle formation. J. Virol., 85, 2050-2059.
Schmitt, P.T., Ray, G., and Schmitt, A.P. (2010). The C-terminal end of PIV5 NP protein is important for virus-like particle production and M-NP protein interaction. J. Virol. 84, 12810-12823.
Pei, Z., Bai, Y., and Schmitt, A.P. (2010). PIV5 M protein interaction with host protein angiomotin-like 1. Virology 397, 155-166.
Harrison, M.S., Sakaguchi, T., and Schmitt, A.P. (2010). Paramyxovirus assembly and budding: building particles that transmit infections. Intl. J. Biochem. Cell Biol. 42, 1416-1429.
Li, M., Schmitt, P.T., Li, Z., McCrory, T.S., He, B., and Schmitt, A.P. (2009). Mumps virus matrix, fusion, and nucleocapsid proteins cooperate for efficient production of virus-like particles. J. Virol. 83, 7261-7272.
Schmitt, A.P., Leser, G.P., Morita, E., Sundquist, W.I., and Lamb, R.A. (2005). Evidence for a new viral late domain core sequence, FPIV, necessary for budding of a paramyxovirus. J. Virol. 79, 2988-2997.
Schmitt, A.P. & Lamb, R.A. (2004). Escaping from the cell: Assembly and budding of negative-strand RNA viruses. Curr. Top. Microbiol. Immunol. 283, 145-196.
Schmitt, A.P., Leser, G.P., Waning, D.L., and Lamb, R.A. (2002). Requirements for budding of paramyxovirus simian virus 5 virus-like particles. J. Virol. 76, 3952-3964.
Schmitt, A.P., He, B., and Lamb, R.A. (1999). Involvement of the cytoplasmic domain of the hemagglutinin-neuraminidase protein in assembly of the paramyxovirus simian virus 5. J. Virol. 73, 8703-8712.
Greeshma Ray - Paramyxovirus M-NP interactions
Weina Sun - Host factors that affect Henipavirus budding
Dr. Phuong Schmitt - Assembly and budding of PIV5
Helen Correll - Paramyxovirus M-NP interactions
- Immunology and Infectious Disease Research Faculty
Assembly and budding of paramyxovirus particles.