Vaccine Booster

Jianzhu Chen, professor of biology and a member of the Koch Institute for Integrative Cancer Research at MIT, is pursuing a different strategy from most of his colleagues working on SARS-CoV-2, the virus that causes Covid-19. “We focus on the immune system and fundamental mechanisms as well as their application in cancer immunotherapy, vaccine development, and metabolic diseases,” he explains. Rather than trying to develop a specific vaccine, Chen is pursuing vaccine platform technologies that can be used to enhance any vaccine.

This effort is built on Chen’s previous work on dengue fever, a severe tropical disease transmitted by mosquitos. “We have been working to improve a vaccine against dengue virus infection,” he says, “which has this phenomenon called antibody-dependent enhancement,” in which “non-neutralizing” antibodies bind to the virus but do not destroy it. The immune system’s pathogen-eating macrophages then consume these virus-antibody complexes and become infected themselves, making a subsequent infection worse.

Chen’s team has identified vaccine adjuvants, or enhancing agents, that can increase neutralizing (that is, effective) antibodies while reducing non-neutralizing antibody response in mice and nonhuman primates. The team is confident that using a similar strategy against Covid-19 would improve any vaccine’s effectiveness.

Addressing cytokine storm

Chen is also focusing on the dangerous hyperinflammatory response seen in Covid-19: the cytokine storm that can result when the immune system overreacts to infection.

“We have been working on macrophage biology for quite some time,” Chen says. “SARS-CoV-2 infection is a hyperinflammatory response, and macrophages probably play a critical role in that response.”

“We have identified many compounds, including FDA-approved drugs, bioactive compounds, and natural products that can modulate macrophage activity to become anti-inflammatory,” he says. Such macrophage modulation would likely be used in conjunction with other treatments as a therapeutic strategy for already-infected patients.

A promising result from either research project could be used along with a Covid-19 vaccine to enhance immune response while preventing or reducing the severity of any possible reinfection. But it’s too early to tell what might happen. “We don’t have a vaccine yet,” Chen notes. “It’s not clear when we’ll have one. Even when we have one, it’s not clear how well it will work. It could be 95% protection; it could be 50%. Some of them may not confer much protection at all. But even 50% or 60% is a significant number of people.”

Another challenge, Chen acknowledges, is that medical research must move from theory to lab and ultimately into the real world. Vaccines can be designed and modeled on computers but eventually “we have to test them to see if they work as we expect,” he says. “You have to immunize mice or some other animals and then challenge them with SARS-CoV-2 to see whether the vaccine protects the animals from infection or dramatically minimize disease symptoms. These kinds of studies can’t be modeled computationally.”

Chen also hopes that his particular contributions will have benefits beyond the pandemic. “We’re aiming to develop a vaccine platform prototyped on SARS-CoV-2 that can be used for the development of many other vaccines as well, using the most appropriate technologies.” If that happens, science will have dug at least one substantial jewel out of the depths of an unprecedented public health crisis.