Intramammary immunization with ultraviolet-killed Escherichia coli shows partial protection against late gestation intramammary challenge with a homologous strain

Abstract

The objective of this study was to evaluate the efficacy of intramammary immunization with UV-killed Escherichia coli ECC-Z on prevention of intramammary colonization after a challenge with a dose of the homologous E. coli ECC-Z live bacteria. A total of 10 cows were included in a study to evaluate the efficacy of intramammary immunization. All 10 cows received an intramammary immunization of 100 cfu of UV-killed E. coli ECC-Z bacteria into one hind quarter at the time of dry off. Approximately 2wk before the anticipated calving date, both hind quarters of all cows were challenged with 100 cfu of live E. coli ECC-Z bacteria. Five of the cows were vaccinated parenterally with a commercial J5 bacterin, and 5 cows served as controls with no parenteral vaccination. The cows were then followed over time and infection risk, clinical scores, somatic cell count, and milk production were observed over time. The results of these 10 cows showed partial protection of intramammary immunization on the outcome of a subsequent homologous intramammary challenge. Immunization resulted in a lower probability of infection, a lower bacteria count, lower somatic cell counts and milk conductivity, a lower clinical mastitis score, and increased milk production compared with unimmunized control quarters. Once the analysis was corrected for immunization, parenteral J5 vaccination had no significant effect on any of the measured parameters. These results provide the first evidence that intramammary immunization may improve the outcome of an intramammary E. coli infection in late gestation and onset of mastitis immediately following parturition. Unlike systemic vaccination, which generally does not reduce the intramammary infection risk, the intramammary immunization did show a 5-times reduced odds of an established intramammary infection after challenge. Cytokine profiles indicated a local return of proinflammatory response after challenge as the data showed a more pronounced increase in in IFN-γ with a subsequent negative feedback due to a spike in the level of IL-10 in immunized quarters relative to nonimmunized quarters. Although these results are preliminary and obtained on only 10 cows, the results provide insight into the biological benefits of triggering mucosal immunity in the mammary gland.

An update on environmental mastitis: Challenging perceptions

“…Vaccination does not reduce the negative impact of CM on reproduction, nor the overall number of CM cases (Wilson et al, 2007(Wilson et al, , 2008. The failure of current J5-vaccines to reduce incidence of E. coli IMI is their major limitation, and efforts are underway to enhance infection prevention through intramammary as opposed to systemic vaccination (Pomeroy et al, 2016). Intramammary immunization may trigger mucosal immunity, and targeting mucosal immunity is seen as the next battle in development of mastitis vaccines (Bharathan & Mullarky, 2011).…”

Th17-related mammary immunity, but not a high systemic Th1 immune response is associated with protection against E. coli mastitis

“…More recently, immunization locally with killed Streptococcus uberis had favorable effects on the reduction of mastitis frequency on the next lactation in dairy cows 13 . Local injection with a low number of dead E. coli bacteria also had some protective effects, although it is doubtful if immunity was really present at the time of challenge due to the low severity of the induced mastitis in the control group 14 .…”

Colonization and local host response following intramammary Staphylococcus chromogenes challenge in dry cows

“…The dry period is very important for dairy cows as intramammary infections (IMI) present at the moment of dry off can cure yet non-lactating mammary quarters can also become newly infected with potential negative effects for the start of the next lactation [23,24]. Despite the fact that the dry period is significant for dairy cows' udder health, only a limited number of intramammary challenge studies were conducted in the dry period [25][26][27], and none using NAS. Also, only a few studies have determined cytokine levels in dry period secretion from late gestation dairy cows.…”