The similar distributions of innate cytokines IL-1β and IL-6 and KoRV pol transcription loads (Supplementary Fig. S4) are of interest considering a previous study in mice where increased secretion of IL-1β was induced by, and enhanced, retroviral infection, replication and persistence in vivo by recruiting susceptible cells to the sites of infection creating a positive feedback loop for retroviral infection83. This evidence concerns the gene IL1B and infection.