Comparison of antibody repertories against Staphylococcus aureus in healthy and infected dairy cows with a distinct mastitis history and vaccinated with a polyvalent mastitis vaccine.

Staphylococcus aureus is one of the pathogens most frequently isolated from cases of mastitis worldwide. To decrease the effect of S. aureus mastitis in dairy farming, alternative strategies for controlling mastitis are needed that depend on a better knowledge of cow-to-cow variations in S. aureus antibody production. The present study sought to explore the diversity of S. aureus antibodies produced by dairy cows with a distinct mastitis history and vaccinated with a polyvalent mastitis vaccine. We obtained protein extracts from S. aureus isolates derived from persistent subclinical mastitis. Proteins were fractionated using 2-dimensional gel electrophoresis and Western blotting. Then, Western blotting membranes were exposed to sera from 24 dairy cows that had been divided into the following groups: vaccinated dairy cows that were infected with S. aureus, further subdivided according to whether they (a) remained infected by S. aureus or (b) recovered from the intramammary infection; unvaccinated dairy cows infected with S. aureus; and vaccinated healthy dairy cows with no history of S. aureus mastitis. Proteins found to be reactive by Western blot were identified by mass spectrometry (MALDI/TOF-TOF). Our most important finding was that F0F1 ATP synthase subunit α, succinyl-diaminopimelate desuccinylase, and cysteinyl-tRNA synthetase were potential candidate proteins for the prevention of S. aureus mastitis. This study strengthens the notion that variations among animals should not be ignored and shows that the heterogeneity of antibody production against anti-staphylococcal antigens in animals may enable the identification of new immunotherapy targets.

The interactions and essential effects of intrinsic insulin-like growth factor-I on Leishmania (Leishmania) major growth within macrophages.

Previously, we showed in Leishmania infections that extrinsic insulin-like growth factor (IGF)-I favored Leishmania proliferation and leishmaniasis development. In this study, the interaction of intrinsically expressed IGF-I and Leishmania (Leishmania) major in macrophages was addressed, and a key finding was the observation, using confocal microscopy, of the co-localization of IGF-I and parasites within macrophages. Following stimulation with interferon-γ (IFN-γ), which is known to inhibit IGF-I production in macrophages, we observed a reduction in the expression of both IGF-I mRNA and protein. This reduced expression was accompanied by a reduction in the cellular parasite load that was completely recovered with the addition of extrinsic IGF-I, which suggests an essential role for IGF-I in Leishmania growth.

Specificity of T cells in human resistance to Mycobacterium tuberculosis infection.

Secreted proteins are considered to have an important role in inducing resistance to Mycobacterium tuberculosis infection. We analyzed the proliferation of PBMC from five healthy tuberculin-positive individuals, four tuberculosis patients, and six tuberculin-negative healthy controls to the whole bacilli, the 38- and 10-kDa-secreted antigens, and the 65- and 71-kDa hsp. Comparing the proliferative responses between the two mycobacterial-secreted proteins, we have found that both the 38- and the 10-kDa antigens were recognized by PBMC from healthy tuberculin-positive individuals. However, the magnitude of the proliferation caused by the 10-kDa antigen was significantly higher (P < 0.005) than that with the 38-kDa protein. It was a finding of importance that proliferation to the 10-kDa antigen was comparable to that elicited by the whole bacilli. Characterization of proliferative responses toward the 10-kDa antigen demonstrates that human cells process the 10-kDa antigen prior to its recognition by T cells, and that this process might be through lysosomal pathways. These data confirm the strong T cell response against the M. tuberculosis 10-kDa antigen and demonstrate, for the first time, characterization of cellular activation toward this antigen. The magnitude of the proliferative responses to the 65-kDa hsp in the healthy tuberculin-positive subjects compared with tuberculosis patients was not significantly different (P > 0.01). Finally, PBMC from the healthy tuberculin-positive individuals did not recognize the M. tuberculosis 71-kDa hsp. In summary, human resistant cells to tuberculosis respond to different classes of antigens, including constitutive cell wall proteins, secreted antigens, and hsp.