The immunophysiological basis for vaccinating ruminants against mastitis.

The roles of humoral and cellular defence mechanisms in protection of the mammary gland against bacterial infection are reviewed. Effective protection depends on opsonisation of pathogens and subsequent phagocytosis by neutrophils. A concomitant requirement for protection is the rapid infiltration of neutrophils into the infected gland. Immunological studies have shown the need to prime animals against antigens expressed by bacteria when they grow in vivo. Vaccination procedures which promote these mammary defence mechanisms are discussed.