Xenoantigen-Dependent Complement-Mediated Neutralization of Lymphocytic Choriomeningitis Virus
Lisa Pipperger1, Iris Koske1, Nicole Wild1
1Division of Virology, Medical University of Innsbruck, Innsbruck, Austria.
Abstract:
Neutralization by antibodies and complement limits the effective dose and thus the therapeutic efficacy of oncolytic viruses after systemic application. We and others previously showed that pseudotyping of oncolytic rhabdoviruses such as maraba virus and vesicular stomatitis virus (VSV) with the lymphocytic choriomeningitis virus glycoprotein (LCMV-GP) results in only a weak induction of neutralizing antibodies. Moreover, LCMV-GP-pseudotyped VSV (VSV-GP) was significantly more stable in normal human serum (NHS) than VSV. Here, we demonstrate that depending on the cell line used for virus production, VSV-GP showed different complement sensitivities in nonimmune NHS. The NHS-mediated titer reduction of VSV-GP was dependent on activation of the classical complement pathway, mainly by natural IgM antibodies against xenoantigens such as galactose-α-(1,3)-galactose (α-Gal) or N-glycolylneuraminic acid (Neu5Gc) expressed on nonhuman production cell lines. VSV-GP produced on human cell lines was stable in NHS. However, VSV-GP generated in transduced human cells expressing α-Gal became sensitive to NHS. Furthermore, GP-specific antibodies induced complement-mediated neutralization of VSV-GP independently of the producer cell line, suggesting that complement regulatory proteins potentially acquired by the virus during the budding process are not sufficient to rescue the virus from antibody-dependent complement-mediated lysis. Thus, our study points to the importance of a careful selection of cell lines for viral vector production for clinical use.IMPORTANCE Systemic application aims to deliver oncolytic viruses to tumors as well as to metastatic lesions. However, we found that xenoantigens incorporated onto the viral surface from nonhuman production cell lines are recognized by natural antibodies in human serum and that the virus is thereby inactivated by complement lysis. Hence, to maximize the effective dose, careful selection of cell lines for virus production is crucial.
Insights
Oncolytic virus therapy effectiveness is limited by immune responses. Using human cell lines for virus production prevents inactivation by human serum complement, enhancing therapeutic potential.
Area of Science:
- Virology
- Immunology
- Biotechnology
Background:
- Systemic application of oncolytic viruses is hindered by antibody and complement-mediated neutralization, reducing therapeutic efficacy.
- Pseudotyping vesicular stomatitis virus (VSV) with lymphocytic choriomeningitis virus glycoprotein (LCMV-GP) yields a virus (VSV-GP) with reduced immunogenicity and increased serum stability.
- However, complement sensitivity of VSV-GP can vary based on the cell line used for its production.
Purpose of the Study:
- To investigate the impact of production cell lines on the complement-mediated neutralization of VSV-GP in normal human serum (NHS).
- To determine the role of xenoantigens and antibody responses in VSV-GP inactivation.
- To assess strategies for enhancing the stability and efficacy of systemically applied oncolytic viruses.
Main Methods:
- Production of VSV-GP in various human and nonhuman cell lines, including genetically modified human cells expressing xenoantigens.
- Assessment of VSV-GP stability and infectivity in normal human serum (NHS) through viral titration assays.
- Analysis of complement pathway activation and the role of natural antibodies against xenoantigens (e.g., α-Gal, Neu5Gc).
Main Results:
- VSV-GP produced in nonhuman cell lines was susceptible to complement-mediated neutralization in NHS, primarily due to natural antibodies against xenoantigens.
- VSV-GP produced in standard human cell lines demonstrated stability in NHS.
- However, VSV-GP produced in human cells engineered to express α-Gal became sensitive to NHS-mediated inactivation, and GP-specific antibodies induced neutralization regardless of the producer cell line.
Conclusions:
- The choice of cell line for producing oncolytic viruses like VSV-GP is critical for their stability in human serum.
- Incorporation of xenoantigens from nonhuman production cells triggers complement lysis via natural antibodies, limiting therapeutic effectiveness.
- Utilizing human cell lines, particularly those lacking immunogenic xenoantigens, is crucial for maximizing the effective dose of oncolytic viruses for systemic cancer therapy.
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