Aims: The importance of cathelicidin-1 as an indicator of the severity of mammary infection
Background. Mastitis is an important disease of sheep, affecting their health and welfare.
Objective: The association of the presence of cathelicidin-1 in milk samples from ewes with mastitis
with the severity of the infection.
Methods: Ewes were intramammarily inoculated with Mannheimia haemolytica or Staphylococcus
chromogenes. Conventional (clinical, bacteriological and cytological examinations; milk yield measurements)
and proteomics evaluation (2-DE, MALDI-TOF MS) to record cathelicidin-1 spot optical
densities in milk samples were recorded.
Results: Ewes challenged with M. haemolytica developed clinical and ewes challenged with S.
chromogenes subclinical mastitis (P=0.05). The challenged organism was isolated from milk samples
from inoculated mammary glands; increased somatic cell counts were also recorded. Cathelicidin-
1 was detected in milk samples from the inoculated side of udders of all ewes. Mean spot density
of cathelicidin-1 from samples from inoculated glands of ewes challenged with M. haemolytica
was higher than from ewes challenged with S. chromogenes: 2896 ± 973 versus 1312 ± 361 (P
=0.034). There were significant correlations between the presence of clinical mastitis / somatic cell
counts with the spot density of cathelicidin-1 on 2-DE gels (P=0.043 and P=0.023, respectively).
There was also a significant inverse correlation between the mean spot densities of cathelicidin-1
in milk samples and the milk yield of respective ewes on D10 (P =0.031).
Conclusion: Potentially, cathelicidin-1 could be used as a marker to indicate the severity of damage
to the mammary parenchyma.
Keywords: Biomarker, cathelicidin-1, mastitis, mammary epithelial cells, pathogenesis, proteomics, sheep, somatic cell
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