BOVINE VIRAL DIARRHEA VIRUS (BVDV) CAUSE MAJOR ECONOMIC LOSSES TO US PRODUCERS. BVDV INFECTION CAUSE TEMPORARY IMMUNOSUPPRESSION TO OTHER PATHOGENS. ONE IMPORTANT ORGAN IN THE IMMUNE SYSTEM OF CALVES IS THE THYMUS, AN ORGAN WITH LIMITED REGENERATION CAPABILITIES. BVDV MULTIPLIES IN THE THYMUS DAMAGING THE ORGAN. WE HYPOTHESIZE THAT BVDV INFECTION IN CALVES CAN LEAD TO LONG-TERM OR PERMANENT IMPACT IN THE ANIMAL'S ABILITY TO FIGHT INFECTION. IN THIS PROJECT WE WILL LOOK AT THE IMMUNE RESPONSE DEVELOPMENT TO PATHOGEN (INFLUENZA D) IN A GROUP OF CALVES PREVIOUSLY EXPOSED TO BVDV COMPARED TO A GROUP OF ANIMALS NOT EXPOSED TO BVDV. WE BELIEVE THAT ANIMALS PRE-EXPOSED TO BVDV WILL HAVE A WEAKER AND DELAYED IMMUNE RESPONSE TO THE SECOND PATHOGEN (INFLUENZA). WE WILL ANALYZE THE IMMUNE RESPONSE BY CHARACTERIZING THE IMMUNE CELL CIRCULATING IN THE CALVES AND WE WILL ANALYZE THE FUNCTION OF THE THYMUS BY CHARACTERIZING THE GENES EXPRESSED USING NEXT GENERATION SEQUENCING. OUR GOAL IS TO MEASURE AND DEFINE THE DIFFERENCES IN THE IMMUNE RESPONSES BETWEEN GROUPS. THE PROJECT MAY PROVIDE FURTHER SUPPORT TOWARD INDICATION OF A LOGICAL AND ASSERTIVE CONTROL APPROACH TO BVDV IN THE US.