Researchers have identified a new virus in patients with severe brain infections in Vietnam. Further research is needed to determine whether the virus is responsible for the symptoms of disease.
The virus was found in a total of 28 out of 644 patients with severe
brain infections in the study, corresponding to around 4 per cent, but
not in any of the 122 patients with non-infectious brain disorders that
Infections of the brain and central nervous system are often fatal,
and patients who survive - often young children and young adults - are
left severely disabled. Brain infections can be caused by a range of
bacterial, parasitic, fungal and viral agents; however, doctors fail to
find the cause of the infection in more than half of all cases, despite
extensive diagnostic efforts. Not knowing the causes of these brain
infections makes public health and treatment interventions impossible.
Researchers at the Oxford University Clinical Research Unit, the
Wellcome Trust South East Asia Major Overseas Programme and the Academic
Medical Center at the University of Amsterdam identified the virus,
tentatively named CyCV-VN, in the fluid around the brain of two patients
with brain infections of unknown cause. The virus was subsequently
detected in an additional 26 out of 642 patients with brain infections
of known and unknown causes.
Using next-generation gene sequencing techniques, the team sequenced
the entire genetic material of the virus, confirming that it represents a
new species that has not been isolated before. They found that it
belongs to a family of viruses called the Circoviridae, which have
previously only been associated with disease in animals, including birds
Dr Rogier van Doorn, Head of Emerging Infections at the Wellcome
Trust Vietnam Research Programme and Oxford University Clinical Research
Unit Hospital for Tropical Diseases in Vietnam, explains: "We don’t yet
know whether this virus is responsible for causing the serious brain
infections we see in these patients, but finding an infectious agent
like this in a normally sterile environment like the fluid around the
brain is extremely important. We need to understand the potential threat
of this virus to human and animal health."
The researchers were not able to detect CyCV-VN in blood samples from
the patients, but it was present in 8 out of 188 faecal samples from
healthy children. The virus was also detected in more than half of
faecal samples from chickens and pigs taken from the local area of one
of the patients from whom the virus was initially isolated, which may
suggest an animal source of infection.
Dr Le Van Tan, Oxford University Clinical Research Unit, Wellcome
Trust Major Overseas Programme, said: "The evidence so far seems to
suggest that CyCV-VN may have crossed into humans from animals, another
example of a potential zoonotic infection. However, detecting the virus
in human samples is not in itself sufficient evidence to prove that the
virus is causing disease, particularly since the virus could also be
detected in patients with other known viral or bacterial causes of brain
"While detection of this virus in the fluid around the brain is certainly remarkable, it could still be that it doesn't cause any harm. Clearly, we need to do more work to understand the role this virus may play in these severe infections."
The researchers are currently trying to grow the virus in the
laboratory using cell culture techniques to develop a blood assay to
test for antibody responses in patient samples, which would indicate
that the patients had mounted an immune response against the virus. Such
a test could also be used to study how many people in the population
have been exposed to CyCV-VN without showing symptoms of disease.
The team are collaborating with scientists across South-east Asia and in the Netherlands to determine whether CyCV-VN can be detected in patient samples from other countries and better understand its geographical distribution.
Professor Menno de Jong, head of the Department of Medical
Microbiology of the Academic Medical Centre in Amsterdam, said: "Our
research shows the importance of continuing efforts to find novel causes
of important infectious diseases and the strength of current technology
in aid of these efforts."
The study, funded by the Wellcome Trust, the European Union and the
Li Ka Shing Foundation-University of Oxford Global Health Program, was
published today in the journal 'mBio' from the American Society for
Source: Wellcome Trust