Par Alexandra Second
Published on
After Sars-CoV-2, here is the HCirV-1. Behind this term a “new virus” detected at the end of January by scientists from the Institut Pasteur, the Necker-Enfants Malades Hospital AP-HP, Inserm within the Imagine Institute, Paris Cité University and the National Veterinary School of Alfort (EnvA).
More concretely, it is the “first circovirus in humans”, […] a yet unknown species of circovirus, provisionally named HCirV-1″, notes the Institut Pasteur in a press release. Here’s what we know.
A virus specific to pigs and birds
Human circovirus (HCirV-1), by its provisional name, belongs to the Circoviridaea family of “very resistant small DNA viruses”, as the Institut Pasteur press release describes it, was discovered in 1974.
Until now, in fact, the circovirus was present only in the animal world. “Circovirus is a virus common to pigs, present all over the world”, note ainsi l’Iowa State University. It also affects birds and causes respiratory, kidney, dermatological and reproductive problems,” adds the Institut Pasteur.
What is unprecedented is the fact that, almost 50 years after its discovery, scientists have identified this virus for the first time in humans. “While the passage of animal viruses to humans is regularly reported in the scientific literature, it is rare for a new virus to be identified in Europe in a patient”.
Detected in a 61-year-old patient with hepatitis
So what did the researchers find? Patient zero – the first person to be infected with a pathogen in a given population, previously free of the disease or virus, recalls Futura-Sciences – East a 61-year-old woman with chronic hepatitis.
“The patient had unexplained chronic hepatitis, with few symptoms. She had been double heart and lung transplant 17 years earlier, with very regular follow-up “and anti-depressant treatment, indicates Marc Eloit, last author of the study, head of the Discovery of pathogens laboratory at the Institut Pasteur and Professor of virology at National Veterinary School of Alfort (EnvA).
We were able to access many samples over several years, which allowed us to identify this new virus, which was unexpected to say the least.
Liver damage
Samples taken from the patient were sequenced to identify the previously unknown cause of this pathogenic hepatitis. As a reminder, sequencing makes it possible to analyze the DNA of cells.
Once collected, the DNA is placed in a casing and then inserted into a sequencer. The process, which lasts several hours, makes it possible to analyze the genome of the virus, to establish its “identity card”, as detailed in this report fromNews Val-de-Marne at the sequencing center of the Henri-Mondor hospital.
It was last year that scientists noticed anomalies in the situation of the sixty-year-old. Indeed, his liver enzyme level jumped, a potential sign of a liver infection.
“After ruling out common common etiologies, the analysis identified a yet unknown species of circovirus, tentatively named Human circovirus 1 (HCirV-1),” reports the Institut Pasteur, adding that “no other viral or bacterial sequences were found”.
It is therefore liver of the patient who was particularly affected by the circovirus, with 2% to 3% of the cells having been infected. If she is now cured, damage has been observed in her liver. “Once this virus has used the resources of the liver cell to multiply, it destroys it,” details the institution in its press release.
mild symptoms
These sequences also made it possible to understand the absence or weakness of the patient’s symptoms. Thus, “the results showed that the viral genome of HCirV-1 was undetectable in blood samples from 2017 to 2019, then its concentration reached a peak in September 2021″.
But, more generally, the symptoms of this circovirus are not destined to worsen. Patient zero’s symptoms remained mild, and could be identified because she was already being carefully monitored by a medical team due to her double transplant.
How was the patient infected?
For now, this question has not found an answer. “The origin of the virus, virus circulating in humans or virus of animal origin, remains to be identified, as well as the source of the infection itself”, by direct contact or by food, explains the Institut Pasteur .
But research is continuing actively, since a PCR test specific to this circovirus has been developed to make “an etiological diagnosis of hepatitis of unknown origin”. A serological test is also in development.
“To adapt the treatment and follow-up of patients, it is essential for us to know the cause of hepatitis, and in particular to know if it is viral”, explains Professor Anne Jamet, co-author of the study and microbiologist clinic at the Necker-Enfants Malades Hospital AP-HP. “It is always important for clinicians to know whether it is a viral infection or not, in order to adapt the treatment”, adds Professor Eloit.
It is also essential to have the ability to identify a new pathogen when an infection is unexplained and to develop a diagnostic test, as potentially any new case of infection with an emerging pathogen in humans may witness beginning of an epidemic.
Is there a vaccine?
As well as the origin of the virus or the way in which it was transmitted to humans, no vaccine is yet available. “Certain circoviruses are pathogenic for animals and can be vaccinated, especially in pigs,” specifies the Institut Pasteur.
But this case is unprecedented, since it is a question, once again, of the first pathogenic circovirus for humans. There is no reason to be alarmed, says epidemiologist Antoine Flahault, interviewed by BFM TV.
“We should not worry about the discovery of a single case in a patient, who also has very particular immunity”, insists the professor.
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