Animal clinical trials relevant, quantifiable for vaccine development: Study


Amid the controversy over lack of human clinical trial data for vaccine licensure in India, a new study has suggested that animal clinical trials too are “relevant” and “quantifiable” for vaccine development.

A comprehensive animal model study of SARS-CoV-2 published in the peer-reviewed journal Nature Microbiology evaluated three non-human primate species –Indian rhesus macaques, African baboons and new-world origin common marmosets — and young and old animals, to determine susceptibility to the SARS-CoV-2 virus and the development of covid-19 disease. The study found that non-human primates (NHP) showed similar progression of SARS-CoV-2 infection to that of humans, with some becoming more ill than others, and signs of the virus in both the upper and lower respiratory tracts and signs of pneumonia.

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The study by scientists at Texas Biomedical Research Institute and Southwest National Primate Research Center (SNPRC) said, over the course of the study, the macaque and baboon models showed significant promise as animal models for covid-19 disease.

Based on outcomes, researchers recommended use of the macaque as a model to help develop vaccines, while the baboon showed greater disease development, making it a potential option for evaluating anti-viral therapeutics and co-morbidities, such as understanding the connection between covid-19 and diabetes or covid-19 and heart disease.

“Our results tell us that these animal models will provide relevant, quantifiable information moving forward as we delve deeper into understanding the disease and targets for therapeutics and vaccines for human trials,” said Deepak Kaushal, Director of the Southwest National Primate Research Center and lead Principal Investigator on the macaque portion of the study.

Animal models for infectious diseases, such as covid-19, are allowing scientists worldwide to determine whether the candidate vaccines and antiviral therapeutics currently under development will be viable as human interventions. Additionally, animal models enable scientists to understand how the disease progresses in people with compromised immune systems to assist in the development of treatments for these individuals.

“Finding the appropriate animal models for covid-19 allows for these critical discoveries to happen now, and they are an important step in combatting this disease,” said Kaushal. “Without well-documented animal data, the FDA is unlikely to license a vaccine or antiviral therapy for human use, even those currently undergoing human trials, because animal model data assure us that we have a complete picture of the disease and how humans may respond to potential therapies,” he said.

The team of 43 researchers reported clinical, viral, imaging, immunological and histopathological (tissue examination) findings during SARS-CoV-2 infection/COVID-19 disease in all three species of NHPs.

While previous animal studies showed the macaque to be a viable model for SARS-CoV-2, this was the first time that researchers performed a longitudinal study of three different NHPs (looking at disease progression factors over several days) and in both young and older macaques to determine if age is a factor in disease progression.

Researchers used the most comprehensive set of evaluations, ranging from bronchoalveolar lavages (lung fluid collection) and nasal swabs to determine virus presence to chest x-rays and CT scans to evaluate lung health after infection.

This study was also the first report of SARS-CoV-2 infection specifically altering lymphoid cells (T cells) in the lung, which generated a strong and very specific immune response in the macaque, enabling the animals to clear the virus. This finding indicates the NHP model will be useful in understanding the immune response to SARS-CoV-2 and aid in the development of interventions that can create a similar response, as well as help evaluate the safety and effectiveness of vaccines, which require a specific immune response in order to be effective.

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