A field evaluation of two vaccines against Mycoplasma hyopneumoniae infection in pigs

Long-Residence Pneumonia Vaccine Developed Using PEG-Grafted Hybrid Nanovesicles from Cell Membrane Fusion of Mycoplasma and IFN-γ-Primed Macrophages

CD8⁺ T cell responses play a critical regulatory role in protection against mycoplasma infection-related respiratory diseases. Nanovesicles derived from cell membranes have been shown to induce CD8⁺ T cell responses. Moreover, the short residence time of mycoplasma membrane-related vaccines in local lymph nodes limits the efficacy of current mycoplasma vaccines. Here, a long-residence pneumonia vaccine is developed using nanovesicles prepared by cell membrane fusion of Mycoplasma hyopneumoniae and interferon-γ (IFN-γ   )-primed macrophages, which are grafted with polyethylene glycol to increase residence time in the lymph nodes. Upregulation of intercellular adhesion molecule-1 (ICAM-1) on the membrane of IFN-γ-primed macrophages increases the targeting of the hybrid nanovesicle vaccine to the local lymph nodes, with increased CD8⁺ T cell activation. A mechanistic study reveals that CD8⁺ T cell activation is achieved via a pathway involving upregulation of C-C motif chemokine ligand 2/3 expression by E26 transformation-specific sequences, followed by increased immune-stimulatory activity of dendritic cells. In vivo, prophylactic testing reveals that the hybrid nanovesicle vaccine triggers a long-term immune response, as evidenced by a memory CD8⁺ T cell response against mycoplasma infection. The current study provides a new design strategy for mycoplasma vaccines that involves a hybrid method using biological sources and artificial modification.

Postweaning mortality in commercial swine production II: review of infectious contributing factors

Postweaning mortality is extremely complex with a multitude of noninfectious and infectious contributing factors. In the current review, our objective is to describe the current state of knowledge regarding infectious causes of postweaning mortality, focusing on estimates of frequency and magnitude of effect where available. While infectious mortality is often categorized by physiologic body system affected, we believe the complex multifactorial nature is better understood by an alternative stratification dependent on intervention type. This category method subjectively combines disease pathogenesis knowledge, epidemiology, and economic consequences. These intervention categories included depopulation of affected cohorts of animals, elimination protocols using knowledge of immunity and epidemiology, or less aggressive interventions. The most aggressive approach to control infectious etiologies is through herd depopulation and repopulation. Historically, these protocols were successful for Actinobacillus pleuropneumoniae and swine dysentery among others. Additionally, this aggressive measure likely would be used to minimize disease spread if either a foreign animal disease was introduced or pseudorabies virus was reintroduced into domestic swine populations. Elimination practices have been successful for Mycoplasma hyopneumoniae, porcine reproductive and respiratory syndrome virus, coronaviruses, including transmissible gastroenteritis virus, porcine epidemic diarrhea virus, and porcine deltacoronavirus, swine influenza virus, nondysentery Brachyspira spp., and others. Porcine circovirus type 2 can have a significant impact on morbidity and mortality; however, it is often adequately controlled through immunization. Many other infectious etiologies present in swine production have not elicited these aggressive control measures. This may be because less aggressive control measures, such as vaccination, management, and therapeutics, are effective, their impact on mortality or productivity is not great enough to warrant, or there is inadequate understanding to employ control procedures efficaciously and efficiently. Since there are many infectious agents and noninfectious contributors, emphasis should continue to be placed on those infectious agents with the greatest impact to minimize postweaning mortality.

Clinical efficacy of two vaccination strategies against Mycoplasma hyopneumoniae in a pig herd suffering from respiratory disease

Background

A randomised field trial was conducted on an Austrian farrow-to-finish farm for one year to compare the efficacy of two commercial Mycoplasma hyopneumoniae vaccines. 585 piglets either received the one-shot formulation in group 1 (Hyogen®, 23.9 days of age) or a two-shot vaccine (Stellamune® Mycoplasma, 4.3 and 24.0 days of age) in group 2. Assessment of vaccine efficacy was evaluated by regression analyses through cough monitoring from nursery to slaughter, average daily weight gain from inclusion to slaughter, antibiotic treatment rate (ATR), mortality rate, and lung lesion scoring at slaughter.

Results

In general, coughing was more frequent during late nursery and finishing. No significant differences were found in the coughing index (0.02 vs 0.03) and mean average daily weight gain (560 vs 550 g) between the two groups. ATR was higher in group 2 (3.8 vs 9.6%). At the slaughterhouse check, significant differences in the prevalence of bronchopneumonia (62.9 vs 71.2%) could be found. Extension of lung lesions was also significantly lower in group 1 in terms of enzootic pneumonia (EP) values (p = 0.000, z = − 4.269). There were no significant differences in the rate of scarred lungs (20.0 vs 24.0%) or those affected by dorsocaudal pleurisy (36.8 vs 34.3%).

Conclusions

This trial demonstrated that Hyogen® was superior to Stellamune® Mycoplasma in reducing (I) the prevalence of bronchopneumonic lungs and those affected by cranioventral pleurisy, (II) the extension and severity of EP-like lung lesions, and (III) the rate of antibiotically treated animals against respiratory disease.

Vaccines as alternatives to antibiotics for food producing animals. Part 1: challenges and needs

Vaccines and other alternative products can help minimize the need for antibiotics by preventing and controlling infectious diseases in animal populations, and are central to the future success of animal agriculture. To assess scientific advancements related to alternatives to antibiotics and provide actionable strategies to support their development, the United States Department of Agriculture, with support from the World Organisation for Animal Health, organized the second International Symposium on Alternatives to Antibiotics. It focused on six key areas: vaccines; microbial-derived products; non-nutritive phytochemicals; immune-related products; chemicals, enzymes, and innovative drugs; and regulatory pathways to enable the development and licensure of alternatives to antibiotics. This article, part of a two-part series, synthesizes and expands on the expert panel discussions regarding opportunities, challenges and needs for the development of vaccines that may reduce the need for use of antibiotics in animals; new approaches and potential solutions will be discussed in part 2 of this series. Vaccines are widely used to prevent infections in food animals. Various studies have demonstrated that their animal agricultural use can lead to significant reductions in antibiotic consumption, making them promising alternatives to antibiotics. To be widely used in food producing animals, vaccines have to be safe, effective, easy to use, and cost-effective. Many current vaccines fall short in one or more of these respects. Scientific advancements may allow many of these limitations to be overcome, but progress is funding-dependent. Research will have to be prioritized to ensure scarce public resources are dedicated to areas of potentially greatest impact first, and private investments into vaccine development constantly compete with other investment opportunities. Although vaccines have the potential to improve animal health, safeguard agricultural productivity, and reduce antibiotic consumption and resulting resistance risks, targeted research and development investments and concerted efforts by all affected are needed to realize that potential.

Histological studies on the development of porcine tonsils after birth

Tonsils form the topographically first immune barrier of an organism against the invasion of pathogens. We used histology to study the development of tonsils of pigs after birth. At birth, the tonsils consist of diffuse lymphoid tissue without any lymphoid follicle aggregations. At the age of 7 days, lymphoid follicles appeared in the soft palate tonsil. The lymphoid layer of the nasopharyngeal tonsil, soft palate tonsil, and lingual tonsil became thicker, and lymphoid follicles in the lamina propria were clearly visible at the age of 21 days. Secondary lymphoid follicles were present in the nasopharyngeal tonsil at the age of 50 days, and in the soft palate tonsil at the age of 120 days. Dendritic cells (DCs), CD3⁺ T cells and IgA⁺ B cells in the soft palate tonsil, nasopharyngeal tonsil and lingual tonsil increased continuously, especially during the first 21 days. The results suggested that tonsils have an important role in local immune defense against invading antigens after birth and will be beneficial for understanding the mechanisms of immunity in these animals after nasal and oral vaccination.

Field study on the safety and efficacy of intradermal versus intramuscular vaccination against Mycoplasma hyopneumoniae

The present study compares the safety and efficacy of a needle-free, intradermal Mycoplasma hyopneumoniae vaccine to an intramuscular one. 420 piglets (21+3 days of age) were randomly assigned to two vaccination groups (intradermal vaccination V1 (n=138), intramuscular vaccination V2 (n=144)) and one unvaccinated control group (CG, n=138). As safety parameters clinical observations, local injection site reactions (ISR) and rectal temperatures were assessed. Average daily weight gain (ADWG) and pneumonic lung lesions (LL) were measured as efficacy parameters. ISRs were minor in V1. After both vaccinations, no adverse impact on appetite was observed and mean rectal temperatures remained within physiological range. ADWG during the fattening period was significantly higher in vaccinated groups (V1: 913.4 g, V2: 924.5 g) compared with CG (875.6 g). No differences in ADWG were observed between V1 and V2. Vaccinated pigs had a significantly reduced mean extent of LL compared with CG. V1 was superior in reducing the extent and prevalence of LL compared with V2. These results reveal that a needle-free intradermal vaccination is safe and efficacious in reducing both the prevalence and extent of lung lesions, as well as in improving performance parameters, in a farrow-to-finish farm with a late onset of M hyopneumoniae infection.

Detection and phylogenetic analysis of Mycoplasma hyopneumoniae from Tibetan pigs in western China

Enzootic pneumonia (EP), often caused by Mycoplasma hyopneumoniae, occurs in Tibetan pigs between October and December in Western China. The aim of this study was to determine the prevalence of M. hyopneumoniae in Tibetan pig herds and also the prevalence of infection. M. hyopneumoniae was detected using enzyme-linked immunosorbent assay, polymerase chain reaction (PCR), and 16S rRNA sequencing. Twenty-nine inflammatory gross-lesions were observed in 155 lungs of slaughtered pigs. Invasion of focal lymphocytes was confirmed by paraffin sectioning and hematoxylin-eosin staining of lung sections. Bronchoalveolar lavage fluid (BALF) from slaughtered Tibetan pigs and nasal swabs from others were assayed using PCR. The prevalence of M. hyopneumoniae in Tibetan pig herds (via ELISA) was 20.48% (93/454) in 3 provinces (Sichuan, Tibet autonomous region, and Qinghai) between October and December of 2014. The difference in prevalence among animals in six different growing stages was statistically significant (P < 0.05). Anti-M. hyopneumoniae antibody was detected in breeding sows (45.83%; 22/48) and piglets (50%; 3/6). PCR and gel electrophoresis of BALF showed that 6.45% (10/155) of pigs were positive for M. hyopneumoniae. The presence of M. hyopneumoniae in serum was higher in piglets and breeding sows than in any other group. In conclusion, the results of this study showed that M. hyopneumoniae is prevalent among Tibetan pigs between October and December in Western China. To the authors' knowledge, this is the first investigation of M. hyopneumoniae prevalence in Tibetan pigs of Western China using serological tests, PCR, and 16S rRNA sequencing.

Mycoplasma fermentans deacetylase promotes mammalian cell stress tolerance

Mycoplasma fermentans is a pathogenic bacterium that infects humans and has potential pathogenic roles in respiratory, genital and rheumatoid diseases. NAD⁺-dependent deacetylase is involved in a wide range of pathophysiological processes and our studies have demonstrated that expression of mycoplasmal deacetylase in mammalian cells inhibits proliferation but promotes anti-starvation stress tolerance. Furthermore, mycoplasmal deacetylase is involved in cellular anti-oxidation, which correlates with changes in the proapoptotic proteins BIK, p21 and BIM. Mycoplasmal deacetylase binds to and deacetylates the FOXO3 protein, similar with mammalian SIRT2, and affects expression of the FOXO3 target gene BIM, resulting in inhibition of cell proliferation. Mycoplasmal deacetylase also alters the performance of cells under drug stress. This study expands our understanding of the potential molecular and cellular mechanisms of interaction between mycoplasmas and mammalian cells.

No Clear Effect of Initiating Vaccination against Common Endemic Infections on the Amounts of Prescribed Antimicrobials for Danish Weaner and Finishing Pigs during 2007-2013

It is often stated that vaccines may help reduce antimicrobial use in swine production. However, limited evidence is available outside clinical trials. We studied the change in amounts of antimicrobials prescribed for weaners and finishers in herds following initiation of vaccination against five common endemic infections: Mycoplasma hyopneumoniae, Actinobacillus pleuropneumoniae, porcine circovirus type II, porcine reproductive and respiratory syndrome virus, and Lawsonia intracellularis. Comparison was made to the change after a randomly selected date in herds not vaccinating against each of the infections. Danish sow herds initiating vaccination during 2007-2013 were included (69-334 herds, depending on the analysis). Danish sow herds with no use of the vaccine in question were included as non-exposed herds (130-570 herds, depending on the analysis). Antimicrobial prescriptions for weaners in sow herds and for finishers in receiving herds were extracted from the VetStat database for a period of 12 months before and 6-18 months after the first purchase of vaccine, or random date and quantified as average animal daily doses (ADDs) per 100 animals per day. The herd-level difference between ADD in the period after and before vaccination was the outcome in linear regression models for weaner pigs, and linear mixed-effects models for finishing pigs, taking into account sow herds delivering pigs to two or more finisher herds. Three plausible risk factors (Baseline ADD, purchase of specific vaccine, purchase of other vaccines) and five confounders (herd size, export and herd health status, year and season) were initially considered in all 10 models. The main significant effect in all models was the Baseline ADD; the higher the Baseline ADD was for weaner and finishing pigs, the larger the decrease in ADD was following vaccination (or random date for non-vaccinating herds). Regardless of vaccination status, almost equal proportions of herds experienced a decrease and an increase in ADD resulting in no overall Change in ADD. Furthermore, only minor effects were found, when vaccinations were used in combination. In conclusion, this study provided little support for the hypothesis that vaccination against five common endemic diseases provides a plausible general strategy to reduce antimicrobial use in Danish pig herds.

EMA and EFSA Joint Scientific Opinion on measures to reduce the need to use antimicrobial agents in animal husbandry in the European Union, and the resulting impacts on food safety (RONAFA)

EFSA and EMA have jointly reviewed measures taken in the EU to reduce the need for and use of antimicrobials in food-producing animals, and the resultant impacts on antimicrobial resistance (AMR). Reduction strategies have been implemented successfully in some Member States. Such strategies include national reduction targets, benchmarking of antimicrobial use, controls on prescribing and restrictions on use of specific critically important antimicrobials, together with improvements to animal husbandry and disease prevention and control measures. Due to the multiplicity of factors contributing to AMR, the impact of any single measure is difficult to quantify, although there is evidence of an association between reduction in antimicrobial use and reduced AMR. To minimise antimicrobial use, a multifaceted integrated approach should be implemented, adapted to local circumstances. Recommended options (non-prioritised) include: development of national strategies; harmonised systems for monitoring antimicrobial use and AMR development; establishing national targets for antimicrobial use reduction; use of on-farm health plans; increasing the responsibility of veterinarians for antimicrobial prescribing; training, education and raising public awareness; increasing the availability of rapid and reliable diagnostics; improving husbandry and management procedures for disease prevention and control; rethinking livestock production systems to reduce inherent disease risk. A limited number of studies provide robust evidence of alternatives to antimicrobials that positively influence health parameters. Possible alternatives include probiotics and prebiotics, competitive exclusion, bacteriophages, immunomodulators, organic acids and teat sealants. Development of a legislative framework that permits the use of specific products as alternatives should be considered. Further research to evaluate the potential of alternative farming systems on reducing AMR is also recommended. Animals suffering from bacterial infections should only be treated with antimicrobials based on veterinary diagnosis and prescription. Options should be reviewed to phase out most preventive use of antimicrobials and to reduce and refine metaphylaxis by applying recognised alternative measures.

Mycoplasmal lipoprotein p37 binds human protein HER2

Mycoplasmas are a group of microbes that can cause human diseases. The mycoplasmal lipoprotein p37 promotes cancer metastasis, at least in part, by interacting with EGFR. In this study, we show that the p37 lipoprotein binds another member of the EGFR family, HER2, through the HER2 extracellular domain. The binding of p37-HER2 promotes phosphorylation of HER2 and activates the downstream signaling molecule Erk1/2. Because the HER2 signaling pathway contributes to breast tumor metastasis, our results imply that the mycoplasmal lipoprotein p37 may also be involved in breast cancer metastasis. This study contributes to our understanding of mycoplasmal lipoprotein p37 function and its potential involvement in tumorigenesis.

Field efficacy study of a novel ready-to-use vaccine against mycoplasma hyopneumoniae and porcine circovirus type 2 in a Greek farm

BACKGROUND

The primary objective of this study was to assess the efficacy, under field conditions, of a novel ready-to use Mycoplasma hyopneumoniae (M hyo) and Porcine circovirus type 2 (PCV2) combination vaccine given to piglets as one vaccination (1-shot) at 3 weeks of age. The study was carried out according to a controlled, randomised, and blinded design in a Greek pig herd with clinical M. hyo and subclinical PCV2 infection. Moreover, based on serology at the time of vaccination, the average PCV2 titre was 9.15 log₂ and represented the level of maternally derived antibodies (MDA). In total 602 healthy suckling piglets, originating from 4 weekly farrowing batches were allocated randomly, within litters, to one of two groups. The pigs in one group were vaccinated with the test product and the other pigs were injected with saline.

RESULTS

Vaccination significantly reduced lesions of craneo-ventral pulmonary consolidation in vaccinated group [expressed as lung lesion score (LLS)] (Mixed model ANOVA: p < 0.0001). The mean LLS was 17.1 in the controls and 10.6 in the treatment group, respectively. The average daily weight gain (ADWG) during the finishing (54 g better in the treatment group) and whole study period (34 g better in vaccinated animals) was significantly greater in vaccinated than control pigs. The vaccinated pigs had a significant reduction of PCV2 viraemia when compared with the controls.

CONCLUSIONS

The test product was considered effective in the face of average MDA, based on significantly reduced severity of LLS and PCV2 viral load, as well as improved ADWG in vaccinated versus control pigs.