, a global zoonosis of pigs, shows regional differences in the prevalence of human-associated disease for Asian and non-Asian countries. The isolation rates and diversities of on tonsils of healthy slaughter pigs in China and the United Kingdom were studied for effects of geography, temperature, pig age, and farm type. Isolates underwent analysis of molecular serotype and multilocus sequence type and virulence-associated genotyping. Although we found no significant difference in positive isolation rates between Chinese and UK farms, the prevalences of serotypes previously associated with human disease were significantly greater in the Chinese collection ( = 0.003). A significant effect of temperature was found on the positive isolation rate of the Chinese samples and the prevalence of human disease-associated serotypes in the UK population (China, = 0.004; United Kingdom, = 0.024) and on the prevalence of isolates carrying key virulence genes in China ( = 0.044). Finally, we found marked diversity among isolates, with statistically significant temperature effects on detection of multiple strain types within individual pigs. This study highlighted the high carriage prevalence and diversity of among clinically healthy pig herds of China and the United Kingdom. The significant effect of temperature on prevalence of isolation, human disease-associated serotypes, and diversity carried by individual pigs may shed new light on geographic variations in human -associated disease. is a global zoonotic pathogen and also a normal colonizer mainly carried on the tonsil of pigs. Thus, it is important to study the effect of environmental and management-associated factors on the populations in clinically healthy pigs. In this research, we investigated the similarities and differences between the populations obtained from different pig ages, seasons, and farm management systems and discovered the relationship between high climatic temperature and the prevalence of .

To reduce the need for antibiotics in animal production, alternative approaches are needed to control infection. We hypothesized that overexpression of native defensin genes will provide food animals with enhanced resistance to bacterial infections. In this study, recombinant porcine beta-defensin 2 (PBD-2) was overexpressed in stably transfected PK-15 porcine kidney cells. PBD-2 antibacterial activities against Actinobacillus pleuropneumoniae, an important respiratory pathogen causing porcine contagious pleuropneumonia, were evaluated on agar plates. Transgenic pigs constitutively overexpressing PBD-2 were produced by a somatic cell cloning method, and their resistance to bacterial infection was evaluated by direct or cohabitation infection with A. pleuropneumoniae. Recombinant PBD-2 peptide that was overexpressed in the PK-15 cells showed antibacterial activity against A. pleuropneumoniae. PBD-2 was overexpressed in the heart, liver, spleen, lungs, kidneys, and jejunum of the transgenic pigs, which showed significantly lower bacterial loads in the lungs and reduced lung lesions after direct or cohabitation infection with A. pleuropneumoniae. The results demonstrate that transgenic overexpression of PBD-2 in pigs confers enhanced resistance against A. pleuropneumoniae infection.T he availability of antibiotics for treating bacterial infection has significantly improved the health of animals and humans. Administration of antibiotics at low doses to food animals has been practiced to promote better health and animal performance in many regions (1). To reduce the development of antimicrobial resistance, approaches to decrease antibiotic use in animal production are needed.Antimicrobial peptides (AMPs), a family of short cationic amphiphilic peptides with antimicrobial and immune modulation activities, exist in nearly every life form as natural anti-infective therapeutic agents (2). Some AMP genes have been used to generate transgenic (TG) mice to enhance resistance to bacterial infection. For example, expression of a synthetic cecropin-class lytic peptide in TG mice displayed enhanced resistance to Brucella abortus (3). Expression of an additional porcine cathelicidin peptide, PR-39, in mice showed increased resistance to group A Streptococcus infection (4). Furthermore, enhanced resistance to Actinobacillus suis infection was observed in proptegrin-1 TG mice (5). These studies demonstrate that AMPs potentially can lead to the development of infection-resistant animals, at least in TG mouse models. However, few reports are available on large food animals such as pigs.Defensins comprise a major family of AMPs, playing an important role in innate immunity. Porcine beta-defensin 2 (PBD-2) is thought to be an important AMP. PBD-2 provides a first line of defense against bacterial infection in pigs, because this AMP is highly expressed in epithelial cells (6, 7); moreover, PBD-2 demonstrates excellent antimicrobial activity with a broad spectrum but without hemolytic activity under physiological conditions (8).In the c...

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Glaesserella parasuis strains were characterized by serotyping PCR, vtaA virulence marker Leader Sequence (LS)-PCR, clinical significance, and geographic region. Overall, the serovars 4, 5/12, 7, 1, and 13 were the most commonly detected. Serovars of greatest clinical relevance were systemic isolates that had a higher probability of being serovar 5/12, 13, or 7. In comparison, pulmonary isolates had a higher likelihood of being serovars 2, 4, 7, or 14. Serovars 5/12 and 13 have previously been considered disease-associated, but this study agrees with other recent studies showing that serovar 7 is indeed associated with systemic G. parasuis disease. Serovar 4 strains illustrated how isolates can have varying degrees of virulence and be obtained from pulmonary, systemic, or nasal sites. Serovars 8, 9, 15, and 10 were predominantly obtained from nasal samples, which indicates a limited clinical significance of these serovars. Additionally, most internal G. parasuis isolates were classified as virulent by LS-PCR and were disease-associated isolates, including serovars 1, 2, 4, 5/12, 7, 13, and 14. Isolates from the nasal cavity, including serovars 6, 9, 10, 11, and 15, were classified as non-virulent by LS-PCR. In conclusion, the distribution of G. parasuis serovars remains constant, with few serovars representing most of the strains isolated from affected pigs. Moreover, it was confirmed that the LS-PCR can be used for G. parasuis virulence prediction of field strains worldwide.