CD4/CXCR4 co-expression allows productive HIV-1 infection in canine kidney MDCK cells
Guillermo Cervantes-Acosta1, Mélanie Welman, Frédéric Freund
1Département de Microbiologie et Immunologie, Université de Montréal, P.O. Box 6128, Station Centre-ville, Montréal, Québec, Canada H3C 3J7. guicerva@uninorte.edu.co
Insights
Researchers created an HIV-1-infectable canine kidney cell line. This new model allows for studying viral budding and glycoprotein transport in polarized cells, advancing human immunodeficiency virus (HIV-1) research.
Area of Science:
- Cell biology
- Virology
- Molecular biology
Background:
- Madin-Darby canine kidney (MDCK) cells are a standard model for studying viral glycoprotein transport and assembly in polarized cells.
- MDCK cells are not naturally infected by human immunodeficiency virus (HIV-1), limiting studies on viral propagation and infection.
- Previous studies used transfected MDCK cells to observe HIV-1 glycoprotein transport and budding, but this model has limitations for productive infection.
Purpose of the Study:
- To establish an MDCK-derived cell line productively infected by HIV-1.
- To enable further studies on the polarization of viral budding in an infectious model.
- To investigate the role of viral proteins in the site-specific budding of HIV-1.
Main Methods:
- Engineered MDCK cells to express HIV-1 receptors (CD4) and co-receptors, rendering them permissive to T-tropic HIV-1 strains.
- Analyzed viral binding, entry, and release from the engineered canine cells.
- Compared the infectivity of viral particles released from different cell surfaces.
- Utilized HIV-1 variants expressing Vpu and Nef to assess their impact on CD4-mediated interference.
Main Results:
- Canine kidney cells were successfully engineered to be permissive to HIV-1 infection.
- Viral particles released from the basolateral surface showed reduced infectivity, attributed to CD4 molecule interference.
- Viruses engineered to down-regulate cell surface CD4 (using Vpu and Nef) largely overcame this infectivity reduction.
- Demonstrated that viral protein function is dependent on the budding site, influenced by glycoprotein targeting signals.
Conclusions:
- An MDCK-derived cell line productively infected by HIV-1 was successfully established.
- This model system is valuable for studying HIV-1 polarization and viral budding mechanisms.
- The study provides further evidence for the site-specific function of viral proteins, influenced by envelope glycoprotein signals and cellular localization.
Abstract:
The Madin-Darby canine kidney (MDCK) cell line has become the prototypic cell type for studying the mechanisms involved in viral glycoproteins transport and viral assembly in polarized cells. This cell line has been used in our laboratories for studying human immunodeficiency virus (HIV-1), despite the fact that MDCK cells cannot be infected by HIV. In transfected MDCK cells, HIV-1 glycoproteins are specifically transported to the basolateral cell surface where viral budding also mostly occurs. However, this model is of limited use when viral propagation, infection of most cells, or larger production of virions, is needed. The initial objective of this work was thus to establish an MDCK-derived cell line that could be productively infected by HIV-1, in order to pursue our studies on the polarization of viral budding. Expression of both receptor and co-receptor for T-tropic strains of the virus showed that canine cells are rendered permissive once virus binding and entry is allowed. In addition, a reduced infectivity of the viral particles released from the basolateral surface was observed. This observation most likely reflects the interference mediated by CD4 molecules that accumulate at the basolateral domain. Accordingly, this effect was largely prevented when using viruses that down-regulate cell surface CD4 by expression of both viral accessory proteins Vpu and Nef. This is a further evidence that the function of different viral proteins depends of the site of viral budding, which is itself determined by the presence of targeting signal(s) harbored by viral envelope glycoproteins.
