Virology: Vaccines and Other Biologics
At the Centre for Biologics Evaluation, viruses are studied in order to improve assays for viral vaccines and other biologics.
- Why we study viruses and vaccines
- How we study viruses and vaccines
- Research highlight 1: Rapid batch testing of vaccines
- Research highlight 2: Development of analytic tests for vaccine-induced host responses
Why we study viruses and vaccines
Viruses are small infectious particles composed of genetic material (DNA or RNA) surrounded by a protein coat. They are not capable of growth or replication outside a living organism. Viruses generally initiate infections through one of three common routes. For example
- Influenza viruses initiate infection in the respiratory pathway and are transmitted through inhalation
- Respiratory Syncytial Viruses (RSV) also attack our respiratory pathway and are transmitted through inhalation.
The immune system can recognize previously encountered pathogens. This function is the reason why many pathogens are unable to cause serious infections in a person the second time that the person encounters it.
Vaccines are biologic agents that trigger this immunological memory through a small or pseudo first infection. This immune system preview allows a more rapid and complete response when the real pathogen is encountered, preventing or lessening the severity of the infection.
In 1796, Edward Jenner demonstrated that infection by the cow-pox virus (vaccinia virus) prevented a subsequent infection by the smallpox virus (variola virus) after observing that milk-maids were seemingly immune to the devastating effects of smallpox. This protective demonstration has since developed into world-wide public health programs to prevent the transmission of serious human pathogens.
In Canada, we are currently using three types of viral vaccines:
- Subunit vaccines
- Live attenuated virus particles
- Inactivated virus particles
Subunit vaccines are composed of recombinant viral proteins as well as an immunostimulatory molecule called an adjuvant. These vaccine types have good safety profiles as all of the components are purified and characterized. However, subunit vaccines tend to be more expensive and induce a smaller immune response when compared with live attenuated vaccines.
Live attenuated viral vaccines are made up of infectious viruses that have been changed, so that they cannot start a systemic infection. Some types can infect single cells, but cannot replicate.
Inactivated whole viruses can also be used as vaccines. In these vaccines, viruses are grown in vaccine-approved cell lines, purified and inactivated. The killed virus vaccines are also given with an adjuvant to boost the immune response.
How we study viruses and vaccines
While enzyme-linked immunosorbent assays (ELISAs) are a standard method for quantifying protein antigens in matrices such as vaccines, the assays have several limitations. ELISAs use a relatively large amount of resources per assay (antibodies, time) and are only capable of examining one analyte per reaction.
Using the standard method, a relatively simple vaccine containing two antigens requires two ELISAs per vaccine lot. If the vaccine has more than two antigenic components or is part of a multi-component vaccine, the number of ELISAs required increases, quickly multiplying the work required for this analysis-based approach. This approach has been used to detect cytokines, pathogens and antibodies. The advantages of these assays are increased speed, reproducibility, and multiplexing or the capacity to simultaneously detect the multiple analytes.
Other assays aimed at evaluating host responses induced by vaccines include flow cytometry. It is an assay for the determination of surface markers on the immune cells in the host. Such assay would allow us to better understand how our body responds to vaccines.
Research highlight 1: Rapid batch testing of vaccines
Influenza infection occurs in as much as 5-15% of the world population, resulting in 3-5 million cases of severe illness and up to 500,000 deaths annually. While vaccination remains the most effective means to prevent and contain influenza, the current flu vaccines have inherent weakness because they have to be updated annually and can only protect the humans within one year. Therefore, it is desirable to explore next generation of flu vaccine capable of inducing long lasting immune responses. Currently, we are developing several immunoassays for multi-component vaccines or next generations of universal flu vaccines.
We are working to
- Develop an assay to quantify components of anti-viral vaccines especially next generation of flu vaccines which otherwise wouldn’t be detected by the traditional methods
Research highlight 2: Development of new immunological analysis assays for respiratory syncytial viral vaccine
Respiratory syncytial virus (RSV) infection is a severe threat to young children and the elderly. Despite decades of research, there is no vaccine is available. The slow progress in RSV-vaccine development in the last several decades is largely to due to a lack of critical elements necessary for evaluating the efficacy and safety associated with RSV vaccines
We are working to
- Develop a new test for the quality analyses of prototype RSV vaccines
- Better understanding vaccine-induced host responses.
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