Oncolytic Measles Virus
Oncolytic viruses have become serious contenders in cancer treatment. They preferentially infect and lyse cancer cells whilst leaving normal tissue unharmed. Measles virus (MV) is potentially oncotropic in nature and holds oncolytic properties by syncytia formation. With years of experience in immunology and oncology, Creative Biolabs provides a one-stop solution for oncolytic measles virus construction and engineering. Our brilliant scientists can manipulate the genome of measles virus to obtain novel and effective recombinant oncolytic MV. The oncolytic viruses can be manipulated to alter the capsid to reduce pathogenicity and immunogenicity, to secrete antibody to boost the anti-tumor immune response, to express cytokine/chemokine to attract immune cells migration to the tumor site, and even to be loaded with immune checkpoint inhibitors.
Brief Introduction of MV
MV is a member of the genus Morbillivirus under the family Paramyxoviridae of the Mononegavirales. It is an enveloped single-stranded negative-sense RNA virus with a 16 kb long genome comprising six genes that encode eight viral proteins: the nucleoprotein (N), phosphoprotein (P), matrix (M), fusion (F), hemagglutinin (H) and large (L) protein, as well as the two accessory non-structural proteins C and V which are encoded by the P-cistron. The viral genome is encapsidated by N, P and L proteins forming the ribonucleoprotein complex (RNP), which is surrounded by M protein. V and C are primarily implicated in the prevention of type 1 interferon (IFN)-induced immune responses. H and F proteins mediate virus attachment and fusion, respectively.
Fig.1 A diagrammatic representation of the measles virus structure. (Aref, 2016)
MV Receptors
The H glycoprotein naturally interacts with the three known MV receptors: CD150 or signal lymphocyte-activation molecule (SLAM), CD46, and nectin-4, also known as Poliovirus receptor-related 4 (PVRL4).
- SLAM is the main receptor for wildtype MV strains that is predominantly expressed on activated B and T lymphocytes, immature thymocytes, monocytes and dendritic cells (DCs).
- CD46, often over-expressed in many tumor cells, has become the preferred target of oncolytic MV. Usually, MV Edmonston-B (MV-Edm) vaccine strains are attenuated lineages with selective oncolysis. They have adapted to use CD46 receptor through a single amino acid substitution at position 481 in MV-H protein (asparagine to tyrosine).
- Nectin-4, an adherens junction protein, is exploited by both wildtype and vaccine strains to facilitate MV cellular entry. It plays an important role in MV pathogenesis by 'shedding' the virus in epithelial airways through the course of infection.
MV as an Oncolytic Virus
MV virotherapy is mainly based on the tumor-selective oncolytic properties of the attenuated MV vaccine strains derived from the MV-Edm vaccine lineage. MV-Edm derivatives preferentially enter cells via MV CD46 receptor and show considerable genetic stability and less pathogenicity. MV-Edm vectors and MV-Edm-based oncolytic therapeutics have now been investigated in a wide range of solid and hematologic malignancies.
Engineered MV to Enhance Their Utility as Oncolytic Agents
Reverse genetic system opened the door for the generation of recombinant MVs encoding additional transcription units (reporter gene, cytokine/chemokine, suicide gene) as well as the modification of viral structural and nonstructural protein to modulate virus biology.
Fig.2 Summary of modifications introduced into MV-Edm through genetic engineering. (Hutzen, 2015)
- Monitoring: The virus can be engineered to express reporter genes (CEA: carcinoembryonic antigen; EGFP; LacZ) which enable noninvasive monitoring of the profiles of viral gene expression over time by sampling body fluids.
- Imaging: The virus can be engineered to express the sodium iodide symporter (MV-NIS) which concentrates radioiodine in the infected cell, thus enabling noninvasive monitoring of the sites of MV infection by gamma camera, SPECT-CT or PET-CT imaging.
- Arming: Engineering the virus with genes that enhance the oncolytic efficacy, such as P-gene from wild-type measles, GM-CSF gene, IFN β, IL-13, etc.
- Retargeting: Numerous strategies have been developed to re-direct MV specificity to cancer cells, thereby minimizing off-target side effects and addressing further safety concerns. MV tropism is usually modified by the insertion of tumor-specific ligands at the carboxyl-terminal extensions of the H protein. For example, single-chain antibodies against tumor associate antigens CEA, CD20 and CD38 have all been displayed on recombinant MV to facilitate targeted entry to epithelial carcinoma, non-Hodgkin's lymphoma and myeloma cells, respectively.
The genetic modifications of MV are summarized in the following table.
Table.1 Summary of genetically engineered MV. (Aref, 2016)
Featured Services and Construction Workflow
The clinical application of MV's properties in developing a virotherapeutic vector system is being highlighted by scientific and medical institutions. By using a clonal reverse genetics system, we can generate diversified recombinant viruses to meet different demands from global customers. Our versatile OncoVirapy™ platform allows producing new viruses expressing very large amounts of additional genetic material. We provide a comprehensive range of services covering the whole pipeline of oncolytic MV construction.
- Cloning services: transgene (gene of interest, GOI) synthesis, GOI cloning and confirmation (e.g., reporter genes, antibody, bispecific antibody, cytokine, chemokine, shRNA or gRNA, miRNA), functional validation of transgenes, promoter adjustment, shuttle plasmid construction
- Recombinant virus rescue and recovery with different strategies
- Stable cell line for recombinant virus rescue and packaging
- Viral genes engineering (single gene or different genes combination)
- MV amplification, purification, titering services
- MV whole genome sequencing (WGS) service
Fig.3 Workflow of oncolytic MV construction at Creative Biolabs.
In addition to recombinant MV construction, Creative Biolabs also offers customized oncolytic MV engineering services to promote oncolytic efficiency and safety. Besides, the proof-of-concept validation assay (in vitro and in vivo validation study) for the oncolytic virus is also provided.
References
- Aref, S.; et al. Measles to the rescue: a review of oncolytic measles virus. Viruses. 2016, 8(10): 294.
- Hutzen, B.; et al. Advances in the design and development of oncolytic measles viruses. Oncolytic Virotherapy. 2015, 4: 109.