Covid-19 infection can reactivate several latent viruses in the body: study

LONDON: Covid-19 can reactivate several latent viruses hiding in the body’s cells from previous infections, even in people with chronic fatigue syndrome, a study has found.
The findings, published in the journal Frontiers in Immunology, contribute to our understanding of the causes of myalgic encephalomyelitis/chronic fatigue syndrome, also known as ME/CFS, and the prospects for arriving at a diagnosis.
Intense and long-lasting tiredness, post-exercise malaise, pain and sleep disturbances are hallmarks of the disease.
The causes of the disease are not known with certainty, although it has been established that the onset in most cases follows a viral or bacterial infection.
“Our study now shows that objective measures are available that show physiological differences in the body’s response to viruses between ME patients and healthy controls,” he said. Anders Rosenteacher a Linkoping UniversitySweden, and responsible for the study.
The widespread spread of the SARS-CoV-2 coronavirus during the COVID-19 pandemic has given researchers a unique opportunity to study what happens in people with ME/CFS during a mild viral infection and to compare it with what happens in healthy controls.
The research group, in collaboration with the Braga Clinic in Stockholm, started a study early in the pandemic, involving 95 patients diagnosed with ME/CFS and 110 healthy controls. They provided blood and saliva samples four times a year.
The researchers analyzed samples of antibodies against SARS-CoV-2 and latent viruses and found a special fingerprint of antibodies against common herpes viruses in saliva.
One such virus was the Epstein-Barr virus (EBV), which infected almost everyone. Most people suffer from a mild infection in childhood.
People infected with EBV in their teens can develop glandular fever, also known as “kissing sickness.”
The virus then remains in a latent state in the body.
The EBV virus can proliferate in situations where the immune system is compromised, causing fatigue, autoimmune responses and an increased risk of lymphoma if allowed to continue, the researchers said.
About half of the participants were infected with SARS-CoV-2 during the first wave of the pandemic and developed mild COVID-19, they said. In more than a third of cases, the infection was asymptomatic, so the person was unaware of the infection.
However, after the SARS-CoV-2 infection had passed, the researchers detected specific antibodies in the saliva, suggesting that three latent viruses had been strongly reactivated, one of which was EBV.
Reactivation was seen in both ME/CFS patients and the control group, but was significantly stronger in the ME/CFS group. This can have negative consequences, one of which is that the immune system attacks certain tissues, such as nerve tissue, in the body, the researchers said.
Previous studies have also shown that mitochondria, which produce energy in cells, are affected, suppressing energy metabolism in people with ME/CFS, they said.
“Another important result of the study is that we see antibody differences against reactivated viruses only in saliva, not in blood. This means that in the future we should use saliva samples when studying antibodies to latent viruses,” said Rosen.
He noted that there is a large overlap between the symptoms of ME/CFS and those of long-term Covid, which is experienced by about a third of patients who contract Covid-19.
Exhaustion after light exercise, brain fog and unrefreshing sleep are common symptoms, while impaired lung capacity and abnormal smell and taste are more specific to long Covid.
The findings may contribute to the development of immunoassays to diagnose ME/CFS, and perhaps even long-term Covid, the researchers added.