Vaccines are the most effective prophylactic tool in veterinary medicine. Despite the great success of many vaccines used currently, there is still a constant need for their improvement. An ideal vaccine should contain a variety of immunogens, be safe and efficacious and induce broad humoral and cell-mediated immunity with one or, at most, two administrations given orally rather than by injection, and should be inexpensive. Traditional approaches include attenuated live vaccines, inactivated vaccines and subunit vaccines. Recently, scientific advances in molecular biology, immunology and bioinformatics, as well as the growing number of sequenced genomes of pathogens, have led to significant progress in respect to understanding virulence mechanisms at the molecular level. Genetic engineering has been applied to obtain recombinant bacterial and viral genomes in order to produce a modified and safe product useful in vaccine development. This article presents the progress and novel strategies used in creating new generation vaccines. It focuses on methods of searching for vaccine candidates to construction of vaccines based on recombinant DNA or proteins.
Specimens of gastric mucosa of 17 free-ranging wild boars (Sus scrofa) shot in the Central Poland during 2007/2008 hunting season were investigated for the presence of Helicobacter species. Histopathology, Helicobacter genus-specific 16S rRNA PCR, and DNA sequence analysis were employed. In PCR analysis the presence of Helicobacter's DNA was detected in one stomach. Obtained sequence analysis showed its relatedness to Helicobacter heilmannii type 2. In histopathology of the PCR-positive sample the presence of tightly coiled spiral bacteria was detected on the surface of the antral mucosa, in gastric pits and lumen of the upper parts of antral glands. Potential pathologic significance of the presence of Helicobacter in the stomach of free-ranging wild boars was obscured by the parasitic invasion-caused gastritis, and remains unknown.
The cj0183 and cj0588 genes identified in the Campylobacter jejuni NCTC 11168 genome encode proteins with homology to virulence factors found in other bacteria. Previous studies showed that single mutation in the cj0183 gene does not affect adhesion of C. jejuni to the Caco-2 cell line whereas protein encoded by cj0588 is involved in adherence to the Caco-2 cells. In the presented study differences in invasion index were observed between mutants in both genes and single mutation of cj0588 in 81116 and 81-176 C. jejuni strains. This fact indicates that Cj0183 protein might play some role in invasion of bacteria into host cells.
A total of 69 Campylobacter jejuni and 16 Campylobacter coli strains isolated from chicken, dog and pig stool samples were characterized based on their resistance to five antimicrobial agents and on plasmid pTet profiles. Antimicrobials used in this study were: amoxicillin/clavulanic acid, ciprofloxacin, erythromycin, tetracycline and trimethoprim/sulfamethoxazole. Among the isolates studied, 91.7% were resistant to one or more antimicrobial agent. The highest level of resistance for the whole test group was to trimethoprim/sulfamethoxazole (57.6%), followed by ciprofloxacin (44.2%) and tetracycline (20%). All isolates were susceptible to amoxicillin/clavulanic acid. Strains isolated from chickens were susceptible to erythromycin. Few erythromycin-resistant strains were isolated from dogs and pigs (5.8%). C. coli strains exhibited a higher antibiotic resistance than C. jejuni strains, excluding resistance to trimethoprim/sulfamethoxazole. The pTet plasmid harboring the tet(O) gene was detected in 14 Campylobacter spp. strains. Our studies demonstrate that the majority (71.4%) of tetracycline-resistant isolates carry a plasmid-borne tet(O) gene, particularly strains for which the minimum inhibitory concentration (MIC) are ≥ 256 μg/ml. In conclusion, we have found high-level trimethoprim/sulfamethoxazole, ciprofloxacin and tetracycline resistance in Polish strains isolated from different sources. This study has demonstrated that resistance of Campylobacter species differs depending on both the bacterial species and animal origins. All strains that displayed resistance to four antimicrobial agents were isolated from pigs. Localization of the tet(O) gene on either plasmid or chromosome was not found to be correlated with tetracycline resistance.