New research led by researchers at Massachusetts General Hospital (MGH), published in Nature Communications, gives an insight that could help improve treatment strategies for patients infected with COVID-19. The researchers looked into what SARS-CoV-2, the virus behind the COVID-19 pandemic, does once it enters a person’s body. The study also analyzed how the infection in lung cells alters the patient’s immune response.
Scientists examined the autopsied material from 24 individuals who have succumbed to COVID-19. Research co-author David T. Ting explained that they had used a method called RNA in Situ hybridization to look at the SARS-CoV-2 virus in human lung specimens. David T. Ting is an MD and associate clinical director for Innovations at the Mass General Cancer Centre and an assistant professor of Medicine at Harvard Medical School, said the method they used has now become a clinical test. Professionals at MGH are using this testing method to understand what tissues the virus can infect.
The analysis highlighted two phases of infection in patients with severe COVID-19 disease. The earlier stage is the period of high levels of virus in the lungs that trigger a patient’s to express genes involved with the interferon pathway. It is a critical part of the immune system response. The virus disappears from the system in the later phase, but the lungs’ damage is too severe for recovery.
Ting said that the interferon response to COVID-19 shows that people’s immune systems can attack SARS-CoV-2, but the immune response is not uniform among the patients and even in different parts of the same patient’s lungs. This odd immune system behavior makes the ‘one drug fits all’ treatment approach difficult. Due to the two-phase nature of the SARS-CoV-2 attack, medicines centered on inhibiting the virus replication, such as Remdesivir, are only useful in the early infection phase.
The research team also discovered a minuscule amount of viral replication in the lungs. This finding indicates that the virus mostly replicates in the nasal passage and then enters the lung, where it causes pneumonia and other severe complications.
It is vital to conduct more of these autopsy analyses to understand the extent and timing of SARS-CoV-2 infection. More research will uncover the specific period the virus takes to infect the lungs and other tissues, leading to improved treatment strategies for COVID-19 patients.