Turkeys at a farm in Virginia do not appear to have been exposed to the highly deadly strain of avian flu seen in other parts of the world, the Agriculture Department said Wednesday.

State officials on Monday banned all live poultry sales and shows for the rest of the month after a flock of 54,000 turkeys at a Shenandoah County farm tested positive for avian flu antibodies. The state of West Virginia followed with a 30-day suspension on shows and sales.

The USDA's National Veterinary Services Laboratories on Wednesday confirmed the presence of antibodies that indicate a possible prior exposure to an H5N1 avian influenza virus that does not pose a threat to humans, the department said in a statement.

Several thousand poultry samples collected from poultry operations in the area of the affected farm, which has not been identified publicly, have tested negative for avian influenza. The finding reinforces the conclusion that the case involves a common avian influenza virus that poses no threat to human health, the USDA said.

"Every indication is that the virus detected is consistent with the North American strain of low pathogenic H5N1, which is not a human health concern," said the department's chief veterinarian, Dr. John Clifford. "LPAI is commonly found in birds and typically causes only minor sickness or no noticeable symptoms in birds."

LPAI H5N1 has been detected in the United States, most recently in wild birds in October 2006, the department said.

The Agriculture Department said the samples were collected as part of routine surveillance that occurs before the birds are slaughtered. The testing detected only antibodies, which indicate possible past exposure to the virus, and showed no evidence the virus is actually present in the samples, the department said.

The National Veterinary Services Laboratories will do further testing to better characterize the virus to which these birds may have been exposed, according to the department.