Other bacteria infrequently observed were species. IMI without an increase in the somatic cell count (SCC) [2]. Some studies showed that strains from IMI are host-adapted and have characteristics of contagious nature, whereas other strains are not host-adapted and cause transient IMI of environmental nature [1,2]. Despite several years of vaccine trials, there is no effective commercial SF1126 vaccine against mastitis in dairy cows that can prevent clinical disease and associated production losses. The only commercial vaccine UBAC??vaccine (UBAC?) (Laboratory of Hipra, S. A. Amir (Girona), Spain) that exists in Europe, Canada, and few other countries achieved some level of efficacy (partial efficacy) but does not prevent clinical disease and production losses [3]. The UBAC??vaccine from Hipra is also not well characterized under controlled experimental studies and field-based studies to confirm label claims from the producer. Intramammary vaccinations of dairy cows with bacterin induced protection from experimental contamination with the same strain [4] but were less effective when challenged with different strains. Subcutaneous injection of live with subsequent booster injection with cell surface proteins through intramammary route induced protection against homologous strain but the efficacy was limited against heterologous strain [5]. Vaccination with multifunction protein (adhesin and glycolytic) glyceraldehyde-3-phosphate dehydrogenase C (GapC) reduced inflammation post-challenge [6]. Some of the technical aspects of the challenge protocols [6] were questionable [7]. Although GapC is usually SF1126 a highly immunogenic protein, its protective effect as vaccine antigen is usually yet to be decided. The in milk or its ability to infect the udder of lactating dairy cows did not change. It was concluded that PauA protein does not have a role in the IMI [11]. has multiple proteins on its cell surface including adhesion molecule (SUAM) and extracellular proteins that bind to host matrix, which allows bacterial adhesion and invasion of udder tissue, resulting in the establishment of IMI [12,13,14,15,16,17,18,19]. Recombinant SUAM (rSUAM) based vaccine efficacy trials in dairy cows induced good immunological responses in vaccinates compared with unvaccinated controls [20]. Under in vitro study, the hyperimmune serum from rSUAM vaccinated cows reduced attachment and internalization into epithelial cells [20]. Intramammary infusion of co-incubated with hyperimmune serum from rSUSAM vaccinates reduced the severity of the disease [21]. The gene mutant clone is usually less virulent SF1126 to epithelial cells [22] and cows [16]. Series of controlled experimental vaccination of cows with rSUSAM and subsequent challenge with heterologous strains showed that rSUAM is usually immunogenic [20]. Similarly, intramammary administration of preincubated with hyperimmune serum from rSUAM vaccinated cows SF1126 reduced clinical SF1126 mastitis and bacterial shedding through milk, post-challenge [21]. Vaccination SAPKK3 trials with a single protein (subunit vaccine), such as glyceraldehyde-3-phosphate dehydrogenase C (GapC) [6], plasminogen activator A (mastitis is limited. Recently, Collado et al. [3] developed a vaccine (UBAC?) (Laboratory of Hipra) which reduced the clinical severity of mastitis, but the induced adaptive immunity was not shown in their report. There is no efficacious vaccine against mastitis in dairy cows. Consequently, the control of mastitis is based on good management practices, such as maintaining clean and dry housing areas, culling chronic cases, dry cow therapy, and treating clinical cases. The search for an effective vaccine that prevents clinical mastitis and associated production losses needs to be based on a profound understanding of humoral and cellular intramammary immunity and knowledge of virulence traits of are not well understood. Encapsulation and biofilm formation [23,24,25,26,27,28], adherence and invasion of mammary epithelial cells [12,14], virulence-associated immunogenic surface proteins [29], and other virulence factors.