Among these thousands of sequences, the researchers identified a sequence from a member of the Cyclovirus genus that was present in two patients, one adult and one child, both with acute central nervous system infections of unknown cause. Follow-up work with a technique called inverse PCR used that short sequence to determine the entire genome sequence of the virus present in one of the samples. CyCV-VN is a unique new species of Cyclovirus, a group that includes no known pathogens.
With the full genome in hand, the researchers went back to 642 samples from patients with suspected acute central nervous system infections and were able to detect the virus in samples from 26 patients (4 percent). The virus was not detected at all in samples from patients with non-infectious conditions of the central nervous system, like multiple sclerosis, a fact that argues that the virus could well be a human pathogen.
The virus was also detected in samples from farm animals in the province where the index patient lived: between 42 percent and 100 percent of fecal samples from pigs, ducks, and chickens in that region harbored viruses that are extremely closely related to CyCV-VN. This raises the possibility - but not certainty - say the authors, that livestock could represent a source for human infection with the virus.
Van also cautions that it is too soon to point an accusing finger at CyCV-VN. "Detection of a virus in human samples alone is insufficient to provide a direct link with an ongoing infection," he says. "Addressing the question of causation requires extensive effort."
Van says they are currently trying to isolate the virus in cell culture and develop a serological assay. If they are able to identify an antibody response to the virus in patient samples, h
|Contact: Jim Sliwa|
American Society for Microbiology