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  • Author or Editor: Li Xu x
  • Medical and Health Sciences x
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In this study, Lactobacillus pentosus expressing porcine lactoferrin (pLF) was tested for in vitro antibacterial activity and for its ability to enhance immunity induced by an orally administered Aujeszky’s disease virus (ADV) vaccine. The cDNA encoding N-terminus of pLF was cloned into a Lactobacillus-specific plasmid to produce L. pentosus pLF expressing transformants (pPG612.1-pLFN/ L. pentosus). The antimicrobial activity of the recombinant pLF protein inhibited bacterial growth in vitro. The supernatant of pPG612.1-pLF-N/L. pentosus had an inhibitory effect on Staphylococcus aureus strain CVCC26003, Bacillus subtilis strain CVCC63501, Escherichia coli strain CVCC10141 and Salmonella enterica ssp. enterica Choleraesuis strain CVCC79102, while it did not inhibit the growth of Lactobacillus casei strain ATCC393. A mouse model was established to test the effectiveness of the orally administered probiotic L. pentosus recombinant strain in the gastrointestinal tract. Mice were immunised with an attenuated porcine Aujeszky’s disease virus (ADV) vaccine. Serum antibody levels determined using a mouse Aujeszky’s disease IgG ELISA showed that IgG levels were significantly higher in the pPG612.1-pLFN/L. pentosus group than in the PBS and Lactobacillus pentosus groups at days 7 and 21 (P < 0.01) and at day 14 (P < 0.05), indicating that this oral recombinant strain can improve the effectiveness of the vaccine and play a role in immune enhancement through humoral immunity. These results suggest that the recombinant Lactobacillus pentosus not only has the beneficial characteristics of lactic acid bacteria but also produces biologically functional lactoferrin.

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Pasteurella multocida, Mannheimia haemolytica and Trueperella pyogenes are three bacterial pathogens closely associated with the bovine respiratory disease complex (BRDC). In the current study, a multiplex PCR for the simultaneous detection of these three bacteria in cultures was established. After serial optimisation, the detection limit of the method for the genomic DNA of the three bacteria was 40 pg/μl. The method could detect the genomic DNA of these three bacteria but not the genomic DNA of seven other bacterial strains. Together with the bacterial enrichment technology, the multiplex PCR could be used for detecting the three bacteria in animal tissues. This method might be valuable for speeding up laboratory diagnosis and directing the treatment of BRDC to these three bacterial pathogens.

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