Japanese scientists created a similar virus about a year ago, but it failed to grow in monkeys.
It does not seem as if the polio virus itself is involved, although similar viruses are known to take up permanent residence in the nervous system.
Monkeypox, which is caused by a virus similar to smallpox, turned out to be one of his next challenges.
A virus may just have been identified, but similar viruses may exist.
Profiles of adaptation in two similar viruses.
Capriati fell ill with a similar virus after her first-round match here last week.
The epidemiology of how koalas and gibbons came to share such similar viruses remains unclear.
By the 1960s, several similar viruses had been discovered and they were classified into the new family Arenaviridae.
It is particularly used when two similar viruses that are infecting the same cell exchange genetic material.
The smallpox vaccine is derived from a similar virus known as vaccinia, which is relatively harmless.