Vaccinia Virus Vaccine
Creative Biolabs enjoys a high reputation in the vaccine industry. The company has been researching and developing vaccines for decades, and has accumulated a wealth of experience and established a mature R&D system. In terms of poxvirus vaccines, the company has a comprehensive research layout and has corresponding and comprehensive services for vaccine research in various members of the poxvirus family.
Vaccinia virus is a member of genus Orthopoxvirus in family Poxviridae and has been widely used for immunization against smallpox.
Immunogenicity of Vaccinia Virus
In the past, scientists have thought that the protective effect against smallpox is related to the presence of neutralizing antibodies in human serum after infection. However, it has now been found that the production of protection is not always correlated with the level of neutralizing antibodies produced after immunization. Activation of CD8+ T cells triggered by vaccination with VACV vaccine is thought to be related to the protective effects of the vaccine. In human, inoculation with Dryvax® at a dose of 2.5 × 105 pfu could activate about 3-14% of CD8+ T cells to produce IFN-γ. And these cells could present markers of memory cell a month after vaccination and would be reactivated again after 6 months of immunization. And a study has been carried out to verify the role of CD8+ T cells in protection for poxvirus infection. The study used naïve mice with depletion of antibody and results showed that CD8+ T cells were necessary for preventing weight loss in these mice and this outcome may due to the non-specific cell-mediated response before the induction of the humoral immune response. Other studies, for example, vaccination of B-cell-deficient mice also support the significance of the early and non-specific cellular immune response.
Applications as A Vaccine for Other Poxviruses
Historically, vaccinia virus is used widely for immunization to induce cross-protection against smallpox until its eradication in the late 1970s. From then on, a series of researches on VACV relating to safety profiles have been put forward and many improved vaccines have been made.
First-Generation VACV Vaccines
The first-generation VACV vaccine involves the global smallpox eradication campaign. A lot of VACV strains were used during that time and New York City Board of Health (NYCBH) strain was widely applied in West Africa and Americas. Till the year 2007, the first vaccine using NYCBH strain of VACV was available in the US. And a derivative of NYCBH strain, EM-63 strain was approved in Russia and India. Lister or Lister/Elstree strain made by Lister Institute in UK was most extensively used vaccine around the world. Other VACV strains were also developed for vaccine like the Temple of Heaven and the Vaccinia Tian Tan (VTT) strains (China), Paris strain (France), the Bern strain (Switzerland), the Copenhagen (Cop) strain (Denmark), the Ankara strain (Turkey) and the Dairen strain (Japan). But these first-generation VACV vaccines often cause adverse complications.
Second-Generation VACV Vaccines
The second-generation VACV vaccines are produced in embryonated chicken eggs and or tissue culture systems, while the first-generation vaccines were manufactured in live animals, which often leads to microbial contamination. The second-generation VACV vaccine, for example, is plaque purified from isolates of the Dryvax® (a representative of first-generation VACV vaccine) and produced in the Vero monkey cell line. In addition, complications that the second-generation VACV vaccines induced are similar to that by the first-generation vaccines.
Third-Generation VACV Vaccines
Because of the safety issues raised by the first- and second-generation vaccines, third-generation VACV vaccines are made via sequential passage to attenuate virulence of the viruses. Such vaccines include Modified Vaccinia Ankara (MVA), Lister clone 16m8 (LC16m8) and Darien I Strain (Dis). These three vaccine candidates are all derived from passage on alternative hosts and MVA has extra ability to trigger proinflammatory cytokines which may be important in inducing adaptive immunity.
Fourth-Generation VACV Vaccines
Compared to third-generation vaccines that reduce viral toxicity by serial passage, the fourth-generation VACV vaccines are attenuated by genetic engineering with the development of biotechnology. There are a number of strategies for obtaining highly attenuated viruses, including deletion of genes responsible for immunomodulation and nucleic acid metabolism in the viral genome. The principle of genetic engineering in VACV is to reduce its virulence meanwhile enhance its immunogenicity. It has been determined that deleting certain genes can attenuate the virulence of the virus, but it is not known whether it can maintain or even improve the immunogenicity of the virus. Studies have shown that deletion of any of the E3L, B15R/184R, or A41L genes enhances T cell responses. NYVAC, VACVΔE3L and VACVvD4-ZG vaccines are representatives of the fourth-generation VACV vaccines.
Vaccinia Virus has always played an important role in protecting poxvirus infections. Creative Biolabs has in-depth systematic research on VACV and has a variety of effective strategies to achieve different application requirements for VACV. The company stocks a variety of VACV strains and is able to adapt and modify them with years of R&D experience to meet the diverse needs of our customers.
All of our products can only be used for research purposes. These vaccine ingredients CANNOT be used directly on humans or animals.
