Periparturient reduction in buffalo of mitogen-induced lymphocyte proliferation and antibody to Toxocara vitulorum

Fuel feeds function: Energy balance and bovine peripheral blood mononuclear cell activation

A general phenomenon in peripartum mammals is the breakdown of (acquired) immunity. The incidence of parasite load, disease and inflammation often rise during the specific energetically demanding time of pregnancy and lactation. In this period, blood leukocytes display decreased DNA synthesis in response to mitogens in vitro. Leukocyte activation, the phase of the cell cycle preceding the DNA synthetic phase has hardly been investigated, but the few studies suggest that leukocyte activation may also be impaired by the limited energy/nutrient availability. Leukocyte activation is characterized by manifold processes, thus, we used the cellular oxygen consumption rate (OCR) as a measure of ATP turnover to support all these processes. We hypothesized that the activation of peripheral blood mononuclear cells (PBMC) - in terms of oxygen consumed over basal levels after in vitro stimulation - is altered by energy balance around parturition. We studied peripartum high-yielding dairy cows because they undergo substantial fluctuations in energy intake, energy output and body fat mass. We established a fluorescence-based test strategy allowing for long-term (≥24h) quantification of O(2)-consumption and studied the peripartum period from 5 weeks ante partum to 5 weeks postpartum. In addition, we determined cellular lactate production, DNA/RNA synthesis and cell size and zoo-technical parameters such as animal energy intake and milk yield were assessed, as well as selected plasma parameters, e.g. glucose concentration. The basal OCR of PBMC from pregnant, non-lactating cows (n=6, -5 weeks ante partum) was 1.19±0.15 nmol min(-1) (10(7)cells)(-1) and increased to maximum levels of 2.54±0.49 nmol min(-1) (10(7)cells)(-1) in phytohemagglutinin (PHA)-stimulated PBMC. The basal OCR did not change over the peripartum period. Whereas the activation indices, herein defined as the PHA-induced 24h-increase of OCR above baseline, amounted to 1.1±0.3, 4.2±0.3, 4.1±1.1, 2.1±0.3, and 2.7±0.5 at weeks -5, -1, +1, +2, and +5 relative to parturition, respectively. Because the activation index was positively correlated to plasma glucose levels and to energy balance during late pregnancy (week -5/week -1) and transition to lactation (week -1/week +2), we conclude that PBMC activation is modulated by energy/nutrient availability. In future studies, the activation index should aid the identification of causal mechanisms of disparity in PBMC activation, such as attenuated ion transport or macromolecule synthesis.

[Immune-humoral response of water buffalo (Bubalus bubalis) against Anaplasma marginale (Theiler, 1910)]

The aim of the present study was to analyze the humoral-immune response of water buffalo (Bubalus bubalis) naturally infected against Anaplasma marginale. For this work, colostrums/milk and blood samples were sequentially collected from buffalo cows prior and after partum for a period of 335 days and from buffalo calves from birth to 365 days after. The antibodies in the colostrums/milk and serum samples of these animals were determined using an ELISA indirect method and the data were analyzed as a mean of a group of animals with the matched ages during the period of 1999/2000 or individually during the year of 2005. The data from animals analyzed in group showed that the antibodies against A. marginale were in low concentration (below the cut off point: D.O. = 0.265 and ELISA levels, EL < or =3), in the sera of buffalo, during the first 90 and 105 days, respectively for cows and calves. Then, the levels of antibodies in the serum samples of buffalo calves, slightly raised to above the cut-off point and kept in higher levels up to approximately 365 days after birth, indicating active acquired immunity. Furthermore, when the animals were individually examined, the buffalo cows showed high antibody levels in the colostrums, but low levels in the blood stream during the first seven days post-partum, suggesting antibody transference from blood to mammary gland. In addition to that, buffalo calves showed high antibody levels during the first 24 hours after suckling colostrum, indicating a colostral passive immunity. By conclusion, the buffaloes were able to arm a humoral immune response against A. marginale and were considered reservoir of this parasite.

Humoral immune response of water buffalo monitored with three different antigens of Toxocara vitulorum

Humoral immune response of water buffalo naturally infected with Toxocara vitulorum was monitored using three different antigens of this parasite in serum and colostrum of buffalo cows and calves. Soluble extract (Ex) and excretory/secretory (ES) larval antigens and perienteric fluid antigen (Pe) of adult T. vitulorum were used to measure the antibody levels by an indirect ELISA. Serum of 7-12 buffalo cows for the first 365 days and colostrum of the same number of buffalo cows for the first 60 days of parturition, and serum of 8-10 buffalo calves for the first 365 days after birth were assayed. The ELISA detected antibodies against all three T. vitulorum antigens in the colostrum and serum of 100% of buffalo cows and calves examined. The highest antibody levels against Ex, ES and Pe antigens were detected in the buffalo cow sera during the perinatal period and were maintained at high levels through 300 days after parturition. On the other hand, colostrum antibody concentrations of all three antigens were highest on the first day post-parturition, but decreased sharply during the first 15 days. Concomitantly to the monitoring of immune response, the parasitic status of the calves was also evaluated. In calves, antibodies passively acquired were at the highest concentrations 24 h after birth and remained at high levels until 45 days coincidentally with the peak of T. vitulorum infection. The rejection of the worms by the calves occurred simultaneously with the decline of antibody levels, which reached their lowest levels between 76 and 150 days. Thereafter, probably because of the presence of adults/larvae stimulation, the calves acquired active immunity and the antibodies started to increase slightly in the serum and plateaued between the days 211 and 365. All three antigens were detected by the serum antibodies of buffalo calves; however, the concentration of anti-Pe antibody was higher than anti-EX and anti-ES, particularly after 90 days of age. By conclusion, the buffalo cows develop immunity and keep high levels of antibodies against T. vitulorum-Ex, ES and Pe antigens and these antibodies are transferred to their calves through the colostrum. This passively acquired immunity does not protect the calves against the acquisition of the infection, but these antibodies, passively or actively acquired, may have an important role during worm rejection by the calves and prevention of intestinal reinfection.

Genetic control of disease resistance and immunoresponsiveness

A great deal of evidence points to substantial genetic control over at least some of the immune responses, although genetic parameters for clinical disease have been less favorable. The past two decades have illustrated that single genes with a large impact on food animal health do exist and can be used to improve the health of domestic populations. The current focus on molecular genetics within food animal species will likely unveil numerous other examples of single genes with large effects, although the use of animals possessing favorable genotypes for disease resistance may represent a compromise in selection for increased production of raw product. Moreover, it is also clear that genetic control over the immune system is not limited to a few genes but is more likely influenced by many genes, each with small effects. The use of this information in animal improvement programs is not straightforward because of factors complicating the identification of superior individuals within the population. The scarcity of information dealing with phenotypic and genetic relationships between measures of disease resistance and aspects of immune response complicates the situation even further. Despite these potential hurdles, the potential for permanent improvement of disease resistance within food animal species in the future is tantalizing and merits intensified future study.

Toxocara vitulorum: maternal transfer of antibodies from buffalo cows (Bubalis bubalis) to calves and levels of infection with T vitulorum in the calves

The levels of antibody to the excretory/secretory antigens of the infective larvae and adults of Toxocara vitulorum were measured by gel precipitation and ELISAs in the serum and colostrum of 12 buffalo cows naturally infected with T vitulorum and in the serum of their calves. The antibody levels were compared with the extent of T vitulorum infection as judged by faecal egg counts in the calves. The patterns of bands of the larval antigens and gel precipitating antibodies in cow serum taken one month before calving, in cow colostrum and in calf serum were very similar. Nine cows and their calves had gel precipitating antibodies but the remaining three cows and their calves did not. The ELISA detected anti-larval antibodies in the colostrum of all 12 cows and calves. With the exception of one calf there was a strong correlation (r = 0.902) between the antibody titre in cow colostrum and the titre of passively acquired antibody in calf serum. The titres of these passively acquired antibodies declined to their lowest levels in calves 12 to 25 days of age; the antibody concentrations then began to increase up to day 42 and remained stable for the remainder of the experiment (105 days). The titres of antibodies to the antigens of the adult worms, examined in four cows and their calves, were lower than the titres to the larval antigens; the calves absorbed this anti-adult antibody from the colostrum and the antibody levels reached a plateau between days 12 and 30 and remained stable for the rest of the experiment.(ABSTRACT TRUNCATED AT 250 WORDS)