Mouse Model Allows for Preparation Against Global Influenza Outbreak

Findings from a new study published by The Journal of Experimental Medicine suggest that a mouse model may be able to identify novel strains of influenza that could result in a global outbreak.

Influenza A can be devastating when transmitted from pigs, birds, or other animals to humans. To be transferred, the virus must mutate to allow it to invade the human immune system, including the MxA protein that protects against avian influenza in vivo; however, the protein is ineffective against strains that have mutated to infect humans, according to the study.

The authors created a transgenic mouse model that expresses human MxA to determine if the protein protects against cross-species infection.

The study authors discovered that the mice models were resistant to avian influenza viruses, but were susceptible to human influenza strains, which is similar to human cell models, according to the study.

MxA is believed to inhibit influenza A by binding to the nucleoprotein that houses the viruses’ genome. Mutations in the nucleoprotein are associated with the ability of influenza to infiltrate human cells.

The authors found that avian influenza strains engineered to have nucleoprotein mutations were able to infect the transgenic mice models, according to the study.

These findings suggest that MxA acts as a shield against cross-species influenza A, but the virus is able to evade immune attack through certain mutations.

The study authors report that this mice model could be used to determine if influenza strains pose a global threat, according to the study. If the strain is deemed harmful, scientists could work to develop a specific vaccination against it to prevent widespread infection.

Influenza can infect any individual, but young children and the elderly are particularly susceptible to infection. The CDC reported that patients infected with influenza can develop bacterial pneumonia, ear infections, sinus infections, dehydration, and worsening of chronic medical conditions, such as congestive heart failure, asthma, or diabetes.

For the 2015/2016 influenza season, the CDC estimated that vaccination prevented approximately 5.1 million influenza infections, 2.5 million influenza-associated medical visits, 71,000 influenza-associated hospitalizations, and thousands of deaths.

Understanding the potential infectious impact of a strain of influenza though mice models can allow the country to better protect itself against an outbreak that could spread around the world, the authors concluded.

"Our MxA-transgenic mouse can readily distinguish between MxA-sensitive influenza virus strains and virus strains that can evade MxA restriction and, consequently, possess a high pandemic potential in humans," said researcher Peter Staeheli, PhD. "Such analyses could complement current risk assessment strategies of emerging influenza viruses, including viral genome sequencing and screening for alterations in known viral virulence genes."