Antibodies to the influenza D virus, a type first isolated from diseased pigs with respiratory disease in 2011, have been detected in horses.
Although the new flu virus was first found in pigs, scientists subsequently discovered it was more common in cattle.
South Dakota State University (SDSU) doctoral student Chithra Sreenivasan, working with the Minnesota Poultry Testing Lab, found no evidence of the new influenza strain in poultry.
However, she did find antibodies to the virus in sheep and goats from the Midwest through blood samples archived at Washington State University.
Sreenivasan co-authored a paper on those findings that was published in the international journal Veterinary Microbiology last year.
In ongoing work, she and her colleagues have since identified antibodies to the D virus in horses.
SDSU Professor Radhey Kaushik said the virus has not been shown to be pathogenic in humans.
“No one should be afraid of this,” he said.
SDSU alumnus Ben Hause, now a research assistant professor at Kansas State University, discovered the virus, which he identified and characterized as part of his doctoral work under Professor Feng Li.
Li and Kaushik secured a National Institutes of Health grant for nearly $US400,000 to continue this work.
Ultimately, the goal is to determine whether the virus can cause problems in humans, Kauschik explained.
“If the virus can undergo reassortment in combination with a closely related human influenza virus, it may be able to form a new strain that could pose more of a threat to humans.”
Meanwhile, Sreenivasan’s current work involves comparing virulence among bovine and swine influenza D strains and human influenza C.
Influenza D has about 50 percent similarity to human influenza C, Sreenivasan explained.
“Human C affects mostly children,” she said, noting that the most common symptom is a runny nose. “It’s not a serious disease. We all have some antibodies because we were infected as children.”
In addition, she is developing a way to study the virus in living cells — trachea and lung epithelial cells from swine and cattle. “I isolate the cells and allow them to grow and then infect them to study the genetic and biologic characteristics,” she said.
Megan Quast, Chithra Sreenivasan, Gabriel Sexton, Hunter Nedland, Aaron Singrey, Linda Fawcett, Grant Miller, Dale Lauer, Shauna Voss, Stacy Pollock, Cristina W. Cunha, Jane Christopher-Hennings, Eric Nelson, Feng Li. Serological evidence for the presence of influenza D virus in small ruminants. Veterinary Microbiology, 2015; 180 (3-4): 281 DOI: 10.1016/j.vetmic.2015.09.005