Veterinary Research Communications

Staats, J.J., Feder, I., Okwumabua, O. and Chengappa, M.M., 1997. Streptococcus suis: past and present. Veterinary Research Communications, 21 (6), 381-407 Steptococcus suis is a Gram-positive, facultatively anaerobic coccus that has been implicated as the cause of a wide range of clinical disease syndromes in swine and other domestic animals. In swine, the disease has spread worldwide but is more prevalent in countries with intensive swine management practices. The disease syndromes caused by S. suis in swine include arthritis, meningitis, pneumonia, septicaemia, endocarditis, polyserositis, abortions and abscesses. S. suis has also been implicated in disease in humans, especially among abattoir workers and swine and pork handlers. In humans, S. suis type 2 can cause meningitis, which may result in permanent hearing loss, septicaemia, endocarditis and death. The pathogenic mechanism of S. suis is not well defined. Several virulence factors have been identified, but their roles in pathogenesis and disease have not been well elucidated. Much work is in progress on characterization of virulence factors and mechanisms, with emphasis on the control of the disease. Because of the non-availability of suitable immunoprophylaxis, control of S. suis infection has depended mainly on the use of antimicrobials.

The pharmacokinetics of erythromycin was studied in five lactating dairy cows following single intramammary infusion of 300 mg erythromycin in each of two quarters per cow with specific mastitis. Levels of erythromycin in plasma and quarter milk samples were measured by agar plate diffusion assay using Micrococcus luteus (ATCC 9341) as the test organism. Erythromycin level in plasma reached a peak concentration value (C max) of 0.07 ± 0.01 μg/ml at 30 min; thereafter, levels declined gradually to reach 0.05 ± 0.00 μg/ml 12 h post drug administration. The pharmacokinetic profile of the drug revealed mean absorption half life (t 1/2ka) as 0.26 ± 0.05 h. The drug was eliminated slowly with elimination half-life (t 1/2β) of 13.75 ± 0.35 h and elimination rate constant (k el) of 0.04 ± 0.00 h−1. The volume of distribution based on the zero-time plasma concentration intercept of the least-squares regression line of the elimination phase (V d(B)) was 0.032 L/kg. The drug crossed to untreated quarters also; mean drug levels of 0.20 ± 0.07, 0.23 ± 0.07, 0.17 ± 0.04, and 0.17 ± 0.04 μg/ml were found at 3, 6, 8 and 12 h, respectively. The mean drug concentration for treated quarters was measured as 22.97 ± 2.31 μg/ml milk at first milking (12 h) following drug infusion. No apparent adverse reaction was seen in cows administered erythromycin. It is concluded that following intramammary infusion erythromycin diffuses readily and extensively in various body fluids and tissues and adequate concentration is maintained in udder tissues for at least 12 h post intramammary administration. Thus, erythromycin may be recommended for local therapy of acute mastitis caused by Gram-positive bacteria in lactating dairy cows.

Chlamydophila abortus is the aetiological agent of enzootic abortion in small ruminants in which it infects the placenta to cause abortion during the last trimester of gestation. In a mouse model, a Th1 immune response involving IFN-γ production and CD8+ T cells is necessary for the infection to be resolved. The authors previously demonstrated that infection with Nippostrongylus brasiliensis, a rodent gastrointestinal nematode extensively used in experimental models to induce Th2 responses, alters the specific immune response against C. abortus infection, increasing bacterial multiplication in liver and reducing specific IFN-γ production. The aim of the present work was to clarify whether a Th2 immune response has any influence on the success of vaccination using both inactivated and attenuated vaccines. The results showed that the Th2 response established prior to vaccination did not influence the induction of protection offered by the vaccines. However, the effectiveness of this protective response can be altered, depending on the adjuvant employed in the inactivated vaccines, when the Th2 response is established after vaccination, just before challenge with C. abortus.

The genus Thunnus comprises many species, some of higher quality and commercial value for their excellent organoleptic features, while others of lower quality and value. Consequently, these species are subjected to frequent fraudulent substitution. Increasing trade in fillet and minced fish makes the identification of external anatomical and morphological features of fish impossible. Proteomics was used for the identification of three Thunnus species. Muscle extracts were evaluated by both mono- and two-dimensional electrophoresis and mass spectrometric techniques. Preliminary results demonstrate that the tested species displays a high degree of polymorphism, making possible an accurate identification.

Fetal bovine lung (FBL) cells are used in the culture of viruses which infect cattle and ISG15 plays a role in innate immunity against viral infections. However, whether the expression of ISG15 gene can be induced in FBL cells is still unknown. In this work, the expression of ISG15 in cultured FBL cells was detected after stimulated with poly I:C or LPS. Real-time PCR analyses revealed that the transcript of ISG15 can be induced by poly I:C or LPS. The increased expression of free ISG15 was confirmed via Western blotting. Furthermore, immunofluorescence assays demonstrated that IRF-3 was translocated from the cytoplasm to the nucleus in the FBL cells treated with poly I:C. Chromatin immunoprecipitation assays showed that IRF-3 can bind to the promoter of the bISG15 gene. To demonstrate IRF-3 can promote the expression of bISG15, we establish a luciferase-reporter system of bovine ISG15 gene in 293 T cells. The luciferase assay showed that the over-expression of bovine IRF-3 could activate the promoter of bISG15 gene. Taken together, these results suggest that the expression of bISG15 can be induced in FBL cells stimulated with poly I:C or LPS, and IRF-3 may play a role in inducing the expression of ISG15 in FBL cells.

The paper describes a method for detecting levamisole and morantel tartrate resistance by determining the percentage of paralysed third stage larvae in serial dilutions of anthelmintic. Levamisole resistantOstertagia spp. had a smaller proportion of larvae undergoing tonic paralysis in either levamisole or morantel tartrate than did a non-resistant strain. The dose response thus obtained for a strain of worms can be tested statistically against strains which are known to be resistant or non-resistant.

The aim of the study was to compare in vitro the stemness features of horse progenitor cells derived from bone marrow (BM-MSCs), amniotic fluid (AF-MSCs) and umbilical cord matrix (EUC-MSCs). It has been suggested that there may be a stem cell population within both umbilical cord matrix and amniotic fluid. However, little knowledge exists about the characteristics of these progenitor cells within these sources in the equine species. This study wanted to investigate an alternative and non-invasive stem cell source for the equine tissue engineering and to learn more about the properties of these cells for future cell banking. Bone marrow, umbilical cord and amniotic fluid samples were harvested from different horses. Cells were analyzed for proliferation, immunocytochemical, stem cell gene expression and multilineage plasticity. BM- and AF-MSCs took similar time to reach confluence and showed comparable plating efficiency. All cell lines expressed identical stem cell markers and capability to differentiate towards osteogenic lineage. Almost all cell lines differentiated into the adipogenic lineage as demonstrated by cytochemical staining, even if no adipose gene expression was detectable for AF-MSCs. AF- and EUC-MSCs showed a limited chondrogenic differentiation compared with BM-MSCs as demonstrated by histological and biochemical analyses. These findings suggest that AF-MSCs appeared to be a readily obtainable and highly proliferative cell line from an uninvasive source that may represent a good model system for stem cell biology. More studies are needed to investigate their multilineage potential. EUC-MSCs need to be further investigated regarding their particular behavior in vitro represented by spheroid formation.

Research on mastitis in dairy cows caused by Escherichia coli has reported the emergence of strains capable of inducing chronic mastitis and that these strains adhered to and internalized into bovine mammary epithelial cells better than strains of E. coli isolated from acute mastitis. To understand mechanisms and strategies used by chronic E. coli strains to survive intracellularly internalization studies using bovine mammary epithelial cells treated with inhibitors of caveolae-mediated endocytosis (CME) and receptor-mediated endocytosis (RME), double immunofluorescence labeling confocal laser and fluorescence microscopy were conducted. Internalization studies showed that strains chronic E. coli strains persisted intracellularly longer than acute E. coli strains. Treatment of bovine mammary epithelial cells CME or RME inhibitors resulted in lower numbers of intracellular E. coli strains associated with chronic or acute mastitis than untreated controls. In addition, when selective CME inhibitors were used significantly fewer chronic E. coli were detected intracellularly than acute E. coli or untreated controls. Confocal laser microscopy showed that chronic E. coli strains colocalized preferentially with caveolae whereas acute strains did so with early endosomes, an early step of RME. These results suggest that strains of E. coli associated with chronic mastitis exploit lipid rafts/CME to internalize into and move through mammary epithelial cells. By exploiting this endocytosis pathway, chronic E. coli strains avoid bactericidal mechanisms such as endosome acidification and endosome-lysosome fusion, thus allowing intracellular survival. Data from this study helps to explain how these strains are capable of causing chronic E. coli mastitis.