May SARS-CoV-2 evolve resistance to COVID-19 vaccines?

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Could SARS-CoV-2 evolve resistance to COVID-19 vaccines?

<img src = "https://scx1.b-cdn.net/csz/news/800/2020/couldsarscov.jpg" alt = "Could SARS-CoV-2 develop a resistance to COVID-19 vaccines?" title = "Schematic representation of three ways in which standard samples from COVID-19 clinical trials can be reused to assess the risk of vaccine resistance. 1. The complexity of the B-cell and T-cell responses can be determined using blood samples Neutralizing antibodies are shown in different colors above. More complex responses indicate evolutionarily more robust immunity. 2. The effect of vaccination on transmission potential can be assessed by collecting virus titre data using routine nasal swabs. Plaque assays of multiple vaccinated and control persons are compiled. Undetectable virus titers indicate little or no transmission potential, either due to complete immune protection or lack of exposure. High virus titers indicate high transmission potential due to the lack of a protective immune response. Marked above with an asterisk indicates a moderate transmission potential due to partial vaccination protection Intermediate titers indicate an increased risk for the development of resistance, as pathogen diversity can be generated within the hosts and selection can take place during transmission between hosts. 3. The pre-existing variation in vaccine resistance can be assessed by extracting genome sequences from nasopharyngeal swabs of symptomatic COVID-19 cases included in the study. In a placebo-controlled double-blind study, significant differences in the genome sequences of samples from vaccinated persons and control persons indicate an at least partial vaccination resistance. Photo credit: Kennedy et al., 2020 (PLOS biology, CC BY 4.0) "width =" 800 "height =" 480 "/>
Schematic representation of three ways in which standard samples from COVID-19 clinical trials can be reused to assess the risk of vaccine resistance. 1. The complexity of B-cell and T-cell responses can be measured using blood samples. Different neutralizing antibodies are shown in different colors above. More complex reactions indicate an evolutionarily more robust immunity. 2. The effect of vaccination on transmission potential can be assessed by collecting virus titer data using routine nasal swabs. Plaque assays from multiple vaccinated individuals and controls are compiled into a histogram. Undetectable virus titers indicate little or no transmission potential, either due to complete immune protection or due to lack of exposure. High virus titers indicate a high transmission potential since there is no protective immune response. Intermediate virus titers, which are marked with an asterisk above, indicate a moderate transmission potential due to partial vaccination protection. Intermediate titers indicate an increased risk for the development of resistance, since pathogen diversity can be generated within the hosts and selection can take place during transmission between hosts. 3. The pre-existing variation in vaccine resistance can be assessed by extracting genome sequences from nasopharyngeal swabs of symptomatic COVID-19 cases included in the study. In a placebo-controlled double-blind study, significant differences in the genome sequences of samples from vaccinated persons and control persons indicate an at least partial vaccination resistance. Photo credit: Kennedy et al., 2020 (PLOS Biology, CC BY 4.0)

Similar to bacteria that develop resistance to antibiotics, viruses can develop resistance to vaccines, and the development of SARS-CoV-2 could undermine the effectiveness of vaccines that are currently being developed. This is evident from an article published Nov. 9 in the open access journal PLOS Biology by David Kennedy and Andrew Read of Pennsylvania State University, U.S. The authors also provide recommendations to vaccine developers to minimize the likelihood of this finding.

"A COVID-19 vaccine is urgently needed to save lives and help society return to its pre-pandemic normal," said David Kennedy, assistant professor of biology. "As we've seen with other diseases like pneumonia, resistance development can quickly render vaccines ineffective. By learning from these previous challenges and implementing that knowledge during vaccine design, we can potentially maximize the long-term impact of vaccines against Covid19 vaccinations."

The researchers specifically suggest that the standard samples of blood and nasal swabs taken during clinical trials to quantify people's responses to vaccination can also be used to assess the likelihood that the vaccines tested will drive resistance development . For example, the team suggests that blood samples can be used to assess the redundancy of immune protection created by vaccine candidates by measuring the types and amounts of antibodies and T cells present.

"Similar to the way combined antibiotic therapy delays the development of antibiotic resistance, vaccines that are supposed to trigger a redundant immune response or in which the immune system is stimulated to target several points, so-called epitopes, on the surface of the virus can prevent the development of vaccine resistance" said Andrew Read, Evan Pugh Professor of Biology and Entomology and Director of the Huck Institute of the Life Sciences. "That's because the virus would have to acquire not just one, but several mutations in order to survive the attack by the host's immune system."

The researchers also recommend that nasal swabs, typically collected during clinical trials, can be used to determine the virus titer or the amount of virus present, which can be viewed as a proxy for the potential for transmission. They found that strong suppression of virus transmission by vaccinated hosts is key to slowing the development of resistance by minimizing the possibility of mutations occurring and reducing the possibility of natural selection acting on the mutations that occur.

In addition, the team suggests that the genetic data collected through nasal swabs can be used to investigate whether vaccine-driven selection has occurred. For example, differences in alleles or forms of genes resulting from mutations between the viral genomes collected from vaccinated and non-vaccinated individuals would indicate that selection has occurred.

"According to the World Health Organization, there are at least 198 COVID-19 vaccines in the development pipeline. 44 are currently under clinical evaluation," Kennedy said. "We suggest using the risk of resistance to prioritize investments among otherwise similarly promising vaccine candidates."

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More information:
PLOS Biology (2020). DOI: 10.1371 / journal.pbio.3001000

Provided by
Pennsylvania State University

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Could SARS-CoV-2 develop resistance to COVID-19 vaccines? (2020, November 9th)
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