Vaccination of pigs with the S48 strain of Toxoplasma gondii – safer meat for human consumption

As clinical toxoplasmosis is not considered a problem in pigs, the main reason to implement a control strategy against Toxoplasma gondii (T. gondii) in this species is to reduce the establishment of T. gondii tissue cysts in pork, consequently reducing the risk of the parasite entering the human food chain. Consumption of T. gondii tissue cysts from raw or undercooked meat is one of the main sources of human infection, with infected pork being considered a high risk. This study incorporates a mouse bioassay with molecular detection of T. gondii DNA to study the effectiveness of vaccination (incomplete S48 strain) in its ability to reduce tissue cyst burden in pigs, following oocyst (M4 strain) challenge. Results from the mouse bioassay show that 100% of mice which had received porcine tissues from vaccinated and challenged pigs survived compared with 51.1% of mice which received tissues from non-vaccinated and challenged pigs. The presence (or absence) of T. gondii DNA from individual mouse brains also confirmed these results. This indicates a reduction in viable T. gondii tissue cysts within tissues from pigs which have been previously vaccinated with the S48 strain. In addition, the study demonstrated that the main predilection sites for the parasite were found to be brain and highly vascular muscles (such as tongue, diaphragm, heart and masseter) of pigs, while meat cuts used as human food such as chop, loin, left tricep and left semitendinosus, had a lower burden of T. gondii tissue cysts. These promising results highlight the potential of S48 strain tachyzoites for reducing the number of T. gondii tissues cysts in pork and thus improving food safety.     

Seed development of Araucaria angustifolia: plant hormones and germinability in 2 years of seeds production

New Forests - During seed development, plant hormones are involved in processes such as the accumulation of reserves, cellular activity and physiological responses. The present study aimed to...     

Variant allometric scaling relationships between bud size and secondary shoot growth in <Emphasis Type="Italic">Quercus faginea</Emphasis>: implications for the climatic modulation of canopy growth

• Introduction and statement of the research questions  

The relationships between primary and secondary growth in tree populations of contrasting climates are poorly understood. We tested the hypotheses that bud size and stem cross-sectional area are related through allometric relationship in shoots and that their scaling slopes change in response to climatic stress.     

Neospora caninum infection as a cause of reproductive failure in a sheep flock

Neospora caninum has been detected only sporadically in cases of ovine abortion, and it has therefore traditionally been considered as an unimportant parasite in small ruminants. This study was carried out with the aim of identifying the pathogen causing serious reproductive problems on a commercial sheep farm. Sera from all rams and ewes tested negative for antibodies against Border disease virus, Schmallenberg virus and Coxiella burnetii, and infections by these agents were therefore ruled out. Nevertheless, seropositivity to N. caninum and/or Toxoplasma gondii was detected, although the seroprevalence was higher in the case of N. caninum. The percentage of lambings and the number of lambs per dam were significantly lower in ewes that were seropositive to N. caninum while no effect on these parameters was detected in ewes that were seropositive to T. gondii. There was also no evidence of infection by T. gondii in the foetal/lamb tissues analyzed by PCR and/or immunohistopathological techniques. On the contrary, the DNA of N. caninum was detected in 13 out of 14 foetuses/lambs descendant from dams seropositive to this parasite. Characteristic lesions caused by N. caninum and/or its antigen were also detected. Genotyping of the N. caninum DNA revealed only two closely related microsatellite multilocus genotypes. The results clearly demonstrate that infection by N. caninum was the cause of the low reproductive performance of this sheep flock.     

Molecular and serological characterization of Leptospira interrogans serovar Canicola isolated from dogs, swine, and bovine in Brazil

The identification of Leptospira clinical isolates through genotyping and serotyping, besides the recognition of its reservoirs, are important tools for understanding the epidemiology of leptospirosis, and they are also keys for identifying new species and serovars. Fourteen clinical isolates from animals were characterized by means of single enzyme amplified length polymorphism, variable number of tandem repeat analysis, pulsed field gel electrophoresis, and serotyping. All isolates were identified as Leptospira interrogans, serovar Canicola. Infections by this serovar occur in urban regions, where dogs represent the main maintenance hosts, whereas bovine and swine may act as reservoirs of serovar Canicola in rural areas. Both urban and rural aspects of leptospirosis, and the role of domestic animals as maintenance hosts, cannot be neglected in developing and developed countries.     

Conception in mares following intrauterine therapy with amikacin

The semisynthetic aminoglycoside amikacin is a potentially valuable antibiotic in broodmare practice due to its efficiency against Gram negative bacteria which have developed resistance to gentamicin. Each of 4 mares conceived when amikacin at 200 ug/ml in buffered extender was used in artificial insemination or as a prebreeding infusion. After intrauterine infusion of 2 g amikacin in 200 ml saline, 4 mares conceived to natural service or insemination with untreated semen after seven hours. In unbuffered saline solutions, amikacin (1 g/100 ml) and gentamicin (1 mg/ml) were spermicidal in vitro.