98 research outputs found
In vitro analysis of expression vectors for DNA vaccination of horses: the effect of a Kozak sequence
One of the prerequisite for developing DNA vaccines for horses are vectors that are efficiently expressed in horse cells
A study of bovine mastitis, milking procedures and management practices on 25 Estonian dairy herds
Background: Mastitis prevalence, milking procedures and management practices were
investigated in 25 big dairy herds supplying milk to an Estonian dairy company. The aim of the study
was to provide information for the company to be used in their new udder health improvement
program to be set up after the completion of this study.
Methods: Quarter milk samples were collected from 3,166 cows for bacterial analysis and SCC
(somatic cell counting). During the farm visit the veterinarian filled in a questionnaire about milking
procedures and management practices with the help of farm managers. If the milk SCC of a cow
or of a quarter exceeded 200,000/ml, the cow was defined as having mastitis.
Results: The percentage of cows having inflammation in one or more quarters measured by SCC
(200,000/ml) was 52.7%. Corynebacterium bovis, Staphylococcus aureus and coagulase negative
staphylococci were the most common bacterial isolates. Women as farm owners, and participating
in the milking, were associated with lower mastitis prevalence on the farm. Peat bedding was
associated with higher mastitis prevalence.
Conclusion: We demonstrated relatively high mastitis prevalence in this study. Contagious
bacteria (eg. S. aureus, C. bovis, S. agalactiae and coagulase negative staphylococci) caused most of
the infections. These infections are usually spread from cow to cow at milking if the milking hygiene
is not good enough. The mastitis situation could be improved by improving milking procedures and
hygiene
Filarioid nematodes in cattle, sheep and horses in Finland
Background: In autumn 2006, Finnish meat inspection data revealed lesions in tendons, muscles
and ligaments of bovine hind legs leading to partial condemnation of carcasses. In gross pathological
examination at Finnish Food Safety Authority Evira, Oulu (now Fish and Wildlife Health) Research
Unit, Onchocerca sp. (Filarioidea; Onchocercidae) nematodes were detected in lesions. Due to this,
a pilot study was made in order to find out what filarioid nematodes do occur in cattle, horses and
sheep in Finland.
Methods: Ventral skin biopsies from 209 dairy cattle and 42 horses, as well as blood samples from
209 cattle, 146 horses and 193 sheep, were collected from different parts of Finland and examined
for microfilariae. Visceral organs and other tissues from 33 cattle with parasitic lesions were
studied histopathologically.
Results: Onchocerca sp. microfilariae (mf), 240 μm long, range 225–260 μm, 5.4 μm thick, were
found in 37% of the skin biopsies of cattle. All blood samples from cattle, horses and sheep and skin
biopsies from horses were negative for mf. Ventral skin microfilaria prevalence in cattle was higher
in southern Finland than in the North (p = 0.001). Animal age and sampling time was not associated
with mf prevalence. The infection was evenly distributed among young and older animals.
Macroscopic lesions on tissues included greenish-grey discolouration and often oedema. In most
of the lesions, small pale nodules were seen on the fasciae. Histopathologic examination of the
samples revealed mild to intense infiltration with eosinophilic granulocytes and multifocal nodular
lymphoplasmacytic aggregations were seen. In some samples, there were granulomatotic lesions
with central necrotic tissue and cell detritus, surrounded by eosinophilic granulocytes, lympho-,
plasma- and histiocytes and some multinucleated giant cells. Around living nematodes no or only
weak inflammatory changes were observed.
Conclusion: Onchocerca sp. infection in cattle was found to be common in Finland, but the amount
of pathological changes leading to condemnation of infected parts is low compared to the mf
prevalence. Pronounced pathological changes are distinct but rare and mild changes are difficult to
distinguish. No other filarioid nematodes were observed from the animals and it appears that
horses and sheep may be free from filarioid nematodes in Finland
Effects of crp deletion in Salmonella enterica serotype Gallinarum
Background.
Salmonella enterica serotype Gallinarum (S. Gallinarum) remains an important pathogen of poultry, especially in developing countries. There is a need to develop effective and safe vaccines. In the current study, the effect of crp deletion was investigated with respect to virulence and biochemical properties and the possible use of a deletion mutant as vaccine candidate was preliminarily tested.
Methods.
Mutants were constructed in S. Gallinarum by P22 transduction from Salmonella Typhimurium (S. Typhimurium) with deletion of the crp gene. The effect was characterized by measuring biochemical properties and by testing of invasion in a chicken loop model and by challenge of six-day-old chickens. Further, birds were immunized with the deleted strain and challenged with the wild type isolate.
Results.
The crp deletions caused complete attenuation of S. Gallinarum. This was shown by ileal loop experiments not to be due to significantly reduced invasion. Strains with such deletions may have vaccine potential, since oral inoculatoin with S. Gallinarum Δcrp completely protected against challenge with the same dose of wild type S. Gallinarum ten days post immunization. Interestingly, the mutations did not cause the same biochemical and growth changes to the two biotypes of S. Gallinarum. All biochemical effects but not virulence could be complemented by providing an intact crp-gene from S. Typhimurium on the plasmid pSD110.
Conclusion.
Transduction of a Tn10 disrupted crp gene from S. Typhimurium caused attenuation in S. Gallinarum and mutated strains are possible candidates for live vaccines against fowl typhoid
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