One of the most common viruses found in the human body is TTV (torquetenovirus), which is also common in monkeys and domestic animals. Its presence to date has not been associated with any disease. But when it starts replicating too much, it’s a sign that something’s wrong with the immune system.
This correlation between elevated TTV load and immunosuppression has already been used in medicine in some contexts, for example, to monitor transplant patients who need to take medication to prevent organ rejection. Now, a new study by the University of São Paulo (USP) suggests that the concentration of TTV in the organism of someone infected with Sars-CoV-2 can serve as a marker of intensity and recovery of covid-19. The results were published in the magazine PLOS ONE.
“We analyzed samples from 91 patients with Sars-CoV-2 infection confirmed by RT-PCR and from another 126 people with the flu-like illness who tested negative. We found that TTV titers increased in those infected with the new coronavirus – the higher, the longer they remained sick – and that the fall in viral load was accompanied by resolution of symptoms. In uninfected individuals, the concentration of TTV remained stable throughout the symptomatic period”, says Maria Cássia Mendes-Correa, professor at the Faculty of Medicine (FM-USP) and one of the authors of the article.
Mendes-Correa coordinates the Laboratory of Medical Research in Virology (LIM52) of the Tropical Medicine Institute of São Paulo (IMT-USP), where for some years TTV has been analyzed in different contexts. The research line is led by Tania Regina Tozetto-Mendoza, biologist and co-author of the recently published work.
“We have been studying TTV as a potential biomarker of certain clinical outcomes, measured in different biological fluids”, says Tozetto-Mendoza.
The current study was developed within the scope of the Corona São Caetano Program, an online platform created to organize the remote monitoring of residents with symptoms of covid-19 by health teams and the collection of samples for diagnosis at home. The initiative involves the Municipal University of São Caetano do Sul (USCS), the local city hall, the startup MRS – Modular Research System and the IMT-USP (read more at: agencia.fapesp.br/33604).
With samples collected from patients assisted by this program, the IMT-USP researchers have been investigating – with support from FAPESP – how the elimination of SARS-CoV-2 varies over time in various body fluids, including blood, urine and saliva .
“So we had the idea of ??analyzing the TTV load in these samples to see if there was any relationship with the clinical picture of covid-19. And the results show that TTV, in fact, can be a marker of disease evolution and resolution. The more symptomatic the patient was, the greater the load of TTV in the sample”, says Mendes-Correa.
The researcher says that all patients included in the research had mild or moderate covid-19. Viral load analysis – both TTV and Sars-CoV-2 – was performed using saliva samples. Through a questionnaire applied to the participants, it was possible to verify that none of them had diseases that cause immunosuppression, such as cancer or AIDS.
“It is believed that covid-19, by causing an immunological imbalance, can lead to a certain degree of immunosuppression. And this favors the replication of TTV”, explains Mendes-Correa.
According to the researcher, there is no direct clinical application for the discovery. But it may, in the future, contribute to improving the diagnosis and prognosis of covid-19.
“Today, we are all looking for ways to obtain a quick and accurate diagnosis. One of the possibilities is to develop a kit capable of measuring several biomarkers of the disease at the same time and then evaluate the results with the help of algorithms. The measurement of TTV load is one of the possibilities. several tests that can be incorporated into these algorithms to support the diagnosis. It is in this direction that medicine is heading”, he says.
The article Torquetenovirus in saliva: A potential biomarker for SARS-CoV-2 infection? can be read at: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0256357.
This text was originally published by Agência FAPESP under the Creative Commons CC-BY-NC-ND license. Read the original here.