Passive transfer of maternal Mycoplasma hyopneumoniae-specific cellular immunity to piglets

Veterinary Population Medicine, College of Veterinary Medicine. University of Minnesota, St. Paul, MN 55108

^* To whom correspondence should be addressed. Email: molit001{at}umn.edu.

	Abstract

Immunity in the neonatal animal is primarily maternally derived, either by lymphocytes that pass into the newborn across the placenta or following colostrum ingestion. However, the effect of this passively transferred cellular maternal immunity on the newborn's immune repertoire is not clearly understood. Various studies have shown that colostral lymphocytes are activated and possess functional abilities; however, no studies have shown the transfer of colostral antigen specific T cell specific responses in a newborn. In this study we examined the transfer of vaccine-induced Mycoplasma hyopneumoniae (M. hyopneumoniae) cellular immunity from immune dams to newborn piglets. Newborn piglets from vaccinated and non-vaccinated dams were assessed in two ways for cellular immune responses specific to M. hyopneumoniae: (1) Delayed-Type Hypersensitivity (DTH) testing; and (2) in vitro lymphocyte proliferation, assayed on piglet blood lymphocytes and sow colostral lymphocytes. DTH responses to M. hyopneumoniae were detected only in offspring of vaccinated sows, whereas DTH responses to the nonspecific mitogen phytohemagglutinin (PHA) were seen in all piglets. M. hyopneumoniae-specific proliferation was seen in colostral lymphocytes from vaccinated sows and in blood lymphocytes from neonatal piglets of vaccinated dams, but not in blood lymphocytes from piglets of non-vaccinated sows. Functional antigen-specific T cells were transferred to offspring from vaccinated sows and participated in the neonatal immune response upon stimulation. This data has implications for defining disease intervention strategies.