Zeev Trainin

Development of a Staphylococcus aureus vaccine against mastitis in dairy cows. I. Challenge trials.

A vaccine composed of three field isolates of Staphylococcus aureus (S. aureus) derived from cases of mastitis in cows was developed. The vaccine was administered to nine uninfected cows while 10 other cows were used as controls. All cows were challenged with a highly virulent S. aureus strain administered into two quarters of each cow. Quarters were tested for clinical signs, secretion of S. aureus, and somatic cell count (SCC). No systemic effects were observed in any of the cows, vaccinated or control. Vaccinated cows had 70% protection from infection compared with fewer than 10% in the controls. Moreover, all quarters challenged in the vaccinated cows, regardless of whether they were successfully infected or not with S. aureus, exhibited very mild inflammatory reactions, identified by their low SCCs (<100,000).

Staphylococcus aureus vaccine against mastitis in dairy cows, composition and evaluation of its immunogenicity in a mouse model

Bovine mastitis caused by Staphylococcus aureus (S. aureus) is a most important infection disease that affects both the quality and the quantity of milk production. Antibiotic therapies formulated for intramammary use are generally unsuccessful in eliminating existing S. aureus infections. Vaccination is a logical approach to the control of S. aureus udder infections. However, to date commercially available S. aureus vaccine have shown limited efficacy under field conditions, mainly due to the paucity of information regarding relevant antigens which will induce a broad spectrum immunization. In the present paper the attempt to develop a new vaccine designated MASTIVAC I is described. MASTIVAC I is composed of three strains of S. aureus namely: VLVL8407; ZO3984 and BS449 which were isolated from clinical and sub-clinical cases of bovine mastitis. A mouse model was used to evaluate the S. aureus specific antibody production and protection of mice against virulent S. aureus strains. The results obtained showed that this vaccine exhibits a broad spectrum of antigenic and immunogenic properties that protects mice from homologues and hetrologous S. aureus challenge.

SHORT-TERMED EXPRESSION OF INTERLEUKIN-12 DURING EXPERIMENTAL BLV INFECTION MAY DIRECT DISEASE PROGRESSION TO PERSISTENT LYMPHOCYTOSIS

In this study an attempt was made to elucidate cellular response cytokine expression upon experimental bovine leukemia virus (BLV) infection in cattle. Progression of infection was monitored by BLV gp51 mRNA expression or DNA amplification by RT-PCR or PCR, respectively, to detect provirus infected cells. Antibodies to BLV were detected by an agar gel immuno-diffusion (AGID) test in 5 weeks and persistent lymphocytosis (PL+) was established in all four BLV-infected animals in 24 weeks after infection. At the initial stage of infection a strong cellular immune response was induced mediated by IL-12p40 mRNA expression. Short-termed IL-12p40 expression was observed in peripheral blood mononuclear cells (PBMC) in two out of four infected animals following 1-3 weeks after infection, while viral mRNA expression was observed 2 weeks following infection. Expression of genes coding for the pro-inflammatory TNFalpha, IL-1beta and cellular response cytokines IFNgamma and IL-2 was detected beginning with the second and third week after infection in all BLV-infected animals. However, IFNgamma expression significantly decreased in 12 weeks after infection in three animals while IL-10 message initially detected 3 weeks after infection increased by 12 weeks and persisted. The observed immediate short-termed cell mediated immune response characterized by IL-12p40 and IFNgamma expression followed by an early shift to an IL-10 induced humoral response, may change the cytokine balance and direct disease progression to the PL+ stage.

Experimental infection of calves with bovine leukemia virus (BLV): an applicable model of a retroviral infection

An experimental model of chronic infection with bovine leukemia virus (BLV) was established in young calves within a relatively short time. In the sera of all infected calves, precipitating antibodies were detected within 5 weeks after infection but upon disease progression pattern of cellular profiles varied. Three calves exhibited transient lymphocytosis 3-5 weeks after infection, two became persistent lymphocytotic (PL+) by that time and one stayed non-lymphocytotic (PL-) for 11 weeks and became PL+ after 4.5 months. Eventually all infected calves became PL+ by the end of the experiment, 6-12 months after infection. Increase of total counts of peripheral blood mononuclear cells (PBMC) related to polyclonal expansion of B-cells. The latter was assessed in all infected calves where the expansion of CD5-bearing cells (B+ CD5+) correlated with increase or decrease of total PBMC counts. Other cell populations such as CD4 and CD8 were also affected. Percentages decreased by 5 weeks after experimental infection to about half their original values though actual cell numbers stayed relatively stable. The experimental model we established compared well with field cases of naturally BLV-infected cattle and thus permitted the investigation of the disease at early stages of infection.

A possible linkage between gonadal hormones, serum and uterine levels of IgG of dairy cows

We have investigated the possible linkage between serum and uterine fluid immunoglobulin G (IgG) levels and the hormonal status of the cow. In cycling cows there was a significant (P < 0.01) drop in average (of 4 consecutive days) serum IgG levels, from 36.4 +/- 6.7 mg ml-1 during the luteal phase of the estrous cycle to 28.3 +/- 5.3 mg ml-1 during and around estrus. In prepartum cows, there was a significant drop (P < 0.01) from an average of 37.6 +/- 3.7 mg ml-1 from 5 consecutive days, i.e. 11-7 before parturition, to 28.0 +/- 5.5 mg ml-1 on the day of parturition. Total IgG in the uterine fluid ranged from 30 to 115 mg in one horn and from 24 mg ml-1 to 70 mg ml-1 in the other horn during the luteal phase, but was essentially undetectable at estrus. The drop in serum and uterine IgG occurred concomitantly with the drop in peripheral serum progesterone, from 2-3 ng ml-1 at the luteal phase, and 11-7 days before calving to less than 0.5 ng ml-1 around estrus and calving. Data suggest a possible linkage between steroid hormone and IgG levels.