Specific pathogen-free (SPF) animal status as a variable in biomedical research: Have we come full circle?

Abstract

In this commentary, we discuss the pros and cons of using specific pathogen-free (SPF) animals in biomedical research, and present individual cases where altering the gut microbiome has dramatically changed the animal's basic physiology, immune/inflammatory functions and susceptibility to infection and disease. We argue that SPF manipulation of the microbiome-host relationship has itself become a confounding variable in biomedical research, which could have major implications to human translation.