In experiments on mice, researchers from the University of California in San Francisco found that the animals fed with house dust from homes that have dogs were protected from a childhood airway infectious agent, called respiratory syncytial virus (RSV).
"RSV infection is common in infants and can manifest as mild to severe respiratory symptoms. Severe infection in infancy is associated with a higher risk of developing childhood asthma," said Kei Fujimura, a researcher on the study.
In the study Fujimura and her colleagues compared three groups of animals: Mice fed house dust from homes with dogs before being infected with RSV, mice infected with RSV without exposure to dust and a control group of mice not infected with RSV.
"Mice fed dust did not exhibit symptoms associated with RSV-mediated airway infection, such as inflammation and mucus production. They also possessed a distinct gastrointestinal bacterial composition compared to animals not fed dust," said Fujimura.
Pet ownership, in particular dogs, has previously been associated with protection against childhood asthma development. Recently Fujimura and her colleagues showed that the collection of bacterial communities (the microbiome) in house dust from homes that possess a cat or dog is compositionally distinct from house dust from homes with no pets.
"This led us to speculate that microbes within dog-associated house dust may colonize the gastrointestinal tract, modulate immune responses and protect the host against the asthmagenic pathogen RSV," said Fujimura.
"This study represents the first step towards determining the identity of the microbial species which confer protection against this respiratory pathogen."
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Identification of the specific species and mechanisms underlying this protective effect represents a crucial step towards understanding the critical role of microbes in defining allergic disease outcomes and could lead to development of microbial-based therapies to protect against RSV and ultimately reduce the risk of childhood asthma development, she added.
The findings were presented at the 2012 General Meeting of the American Society for Microbiology in San Francisco.