Scientists around the world are investigating different modes of treatment for the new coronavirus such as vaccines, convalescent plasma, and antiviral drugs. A new review by researchers at The University of North Carolina at Chapel Hill in the United States proposes several potential therapies for coronaviruses including SARS-CoV-2. The speediest solutions to the global pandemic appear to be antiviral drugs and gene therapies.
“Coronaviruses poses a real threat to human health and the global economy,” says Ralph Baric, a professor and co-author on the study. “We must consider new countermeasures to control the pandemic virus SARS-CoV-2, as well as the wide variety of zoonotic viruses that also pose a threat and may cause problems in the future.”
Undoubtedly, a preventative vaccine would be the most effective tool to challenge COVID-19. According to the WHO, at least 70 vaccines are being developed for the new coronavirus globally, with several having already entered human trials.
Researchers are taking varied routes to develop a vaccine against SARS-CoV-2. Vaccines that target the SARS-CoV-2 spike protein, which mediates the attachment of the virus to the host cell and its subsequent fusion. Additionally, vaccines that take modern routes such as those using DNA or RNA, or nanoparticle vectors are more favourable to traditional vaccines containing live or attenuated virus particles. While a few different types of vaccine are being developed, the long road ahead means other treatment options need to be explored.
Broad-spectrum antiviral drugs are especially encouraging when it comes to looking for drugs that target COVID-19. One example of such hopefuls are nucleoside analogues. Nucleoside molecules are an integral part of DNA or RNA structure. Drugs that imitate some nucleosides can trickily replace their counterparts during DNA synthesis, leading to the halting of viral replication. But coronaviruses possess enzyme proteins that are responsible for accurately copying DNA and fixing any errors—such enzymes can reduce the efficacy of some antiviral drugs. Presently, two antivirals appear to be promising in the fight against COVID-19. The U.S. FDA has granted emergency use authorization to remdesivir while β-D-N4-hydroxycytidine is also being explored as a candidate drug.
While vaccines and drugs may take longer to develop, convalescent plasma is a treatment method that is more immediately accessible. Blood plasma, from patients who have recovered from the condition, contain antibodies that can be used to treat patients with COVID-19. In the past, this method has been used to treat patients during the 1918 flu pandemic. The treatment requires only the use of equipment needed for blood transfusions and while its efficacy needs to be studied further, the immunity of patients can be boosted with the help of these antibodies. This makes it a relatively easy fix for the disease caused due to SARS-CoV-2 that can ease the burden on ICUs and other medical services.
Gene therapy is another possible mode of treatment for COVID-19. In gene therapy, genetic material is administered to a patient’s cells or tissues using a vector such as the adeno-associated virus (AAV). This results in the activation of the immune system and the delivery of a large number of immune molecules to the upper respiratory tracts, resulting in immunization with low levels of toxicity. Compared to other treatment options, gene therapies of this kind can be speedily developed and tested.
“Passive AAV-based immunization can be used as a rapid alternative. It is simple and contains only two components, the viral vector and the antibody,” says Victor Longping, a co-author on the paper. “In theory, a single dose could generate a protective response in one week and last more than a year. It may be too late to treat SARS-CoV-2, but it could still be taken into account for future outbreaks of the disease.”
Reference: Longping et al. 2020. The Current and Future State of Vaccines, Antivirals and Gene Therapies Against Emerging Coronaviruses. Front. Microbiol., April 24, 2020.