Generation of an inactivated vaccine for avian pathogenic Escherichia coli using microarrays; a more rational approach to inactivated vaccine design

Background:

Escherichia coli remains a major pathogen of poultry. Most vaccines are inactivated and produced empirically. Although inactivated Salmonella vaccines have been produced by culture under conditions of Fe deprivation, no vaccines have been produced which are likely to express all the proteins expressed during infection of antigen-presenting cells.

Aim:

The aim was to produce a more protective inactivated vaccine by culturing the avian E. coli in a synthetic medium that resembled the environment of the phagolysosome.

Methods:

Global gene expression in a pathogenic avian O78:K80 strain of E. coli, harvested from infected avian macrophage-like HD11 cells, was compared by microarray with bacteria cultured in a tissue culture medium. A liquid synthetic medium was produced based on the environmental conditions identified to which the bacteria were exposed intracellularly. A bacterin was produced from this strain and its protective ability was assessed in chickens.

Results:

The changes in E. coli gene expression observed included the use of different electron acceptors and carbon sources such as ethanolamine, β-glucosides, galactonate, dicarboxylic acids, and amino acids, up-regulation of genes associated with Fe and Mn uptake, and up-regulation of type-1 and curli fimbriae, other adhesion genes and down-regulation of sialic acid synthesis genes. The bacterin produced in the synthetic medium was statistically more protective than a bacterin prepared from bacteria cultured in the nutrient broth when tested in vaccinated chickens challenged with a different virulent E. coli O78:K80 strain.

Conclusion:

The approach of using gene expression to produce synthetic media for the generation of more effective bacterins could be used for a number of intracellular bacteria pathogens including Enteroinvasive E. coli, Salmonella, and the Pasteurella/Riemerella/Mannheimia group of organisms.

Occurrence of Salmonella Typhimurium and its monophasic variant (4, [5],12:i:-) in healthy and clinically ill pigs in northern Italy

Background

The serovar Typhimurium (4, [5],12:i:1,2), is the most frequently isolated serovar in case of salmonellosis in pigs in Europe and its monophasic variant (4, [5],12:i:-) has been increasingly responsible for Salmonella outbreaks in humans. A total of 25,215 samples were collected, during the years 2002–2017, from 1359 pig farms located in Northern Italy. Samples were collected from different material sources including fecal samples, rectal swabs, gut content and different organs.

Results

Salmonella was isolated in 15.80% of samples and, among the isolates, 733 were typed as Salmonella Typhimurium (ST) or its monophasic variant (MST). Over time, there was an increase of isolation of MST which outnumbered ST. Most of the strains were isolated in animals during the weaning stage and the growing – fattening period whereas the clinical cases were mainly present in young pigs after weaning.

Conclusions

This study confirms the presence of ST and MST in pig farms although, considering the total of isolated serotypes, with lower percentages than previously reported.

In the last few years, ST has increasingly been replaced by MST suggesting that MST has a competitive advantage over ST, probably due to its different antigenicity and pathogenicity which renders the infection stealthier to recognize and control.

Association Between Infectious Agents and Lesions in Post-Weaned Piglets and Fattening Heavy Pigs With Porcine Respiratory Disease Complex (PRDC)

Porcine Respiratory Disease Complex (PRDC) is a multifactorial syndrome that causes health problems in growing pigs and economic losses to farmers. The etiological factors involved can be bacteria, viruses, or mycoplasmas. However, environmental stressors associated with farm management can influence the status of the animal's health. The role and impact of different microorganisms in the development of the disease can be complex, and these are not fully understood. The severity of lesions are a consequence of synergism and combination of different factors. The aim of this study was to systematically analyse samples, conferred to the Veterinary Diagnostic Laboratory (IZSLER, Brescia), with a standardized diagnostic protocol in case of suspected PRDC. During necropsy, the lungs and carcasses were analyzed to determine the severity and extension of lesions. Gross lung lesions were classified according to a pre-established scheme adapted from literature. Furthermore, pulmonary, pleural, and nasal lesions were scored to determine their severity and extension. Finally, the presence of infectious agents was investigated to identify the microorganisms involved in the cases studied. During the years 2014–2016, 1,658 samples of lungs and carcasses with PRDC from 863 farms were analyzed; among them 931 and 727 samples were from weaned piglets and fattening pigs, respectively. The most frequently observed lesions were characteristic of catarrhal bronchopneumonia, broncho-interstitial pneumonia, pleuropneumonia, and pleuritis. Some pathogens identified were correlated to specific lesions, whereas other pathogens to various lesions. These underline the need for the establishment of control and treatment programmes for individual farms.

In vitro Cytokine Responses to Virulent PRRS Virus Strains

Porcine reproductive and respiratory syndrome (PRRS) affects farmed swine causing heavy direct and indirect losses. The infections sustained by PRRS viruses (PRRSV-1 and PRRSV-2) may give rise to severe clinical cases. This highlights the issue of PRRSV pathogenicity and relevant markers thereof. Since PRRSV strains can be discriminated in terms of immunotypes, we aimed to detect possible correlates of virulence in vitro based on the profile of innate immune responses induced by strains of diverse virulence. To this purpose, 10 field PRRSV isolates were investigated in assays of innate immune response to detect possible features associated with virulence. Tumor necrosis factor-α, interleukin (IL)-1beta, IL-8, IL-10, and caspase-1 were measured in cultures of PRRSV-treated peripheral blood mononuclear cells of PRRS-naive pigs, unable to support PRRSV replication. Two reference PRRSV strains (highly pathogenic and attenuated, respectively), were included in the screening. The PRRSV strains isolated from field cases were shown to vary widely in terms of inflammatory cytokine responses in vitro, which were substantially lacking with some strains including the reference, highly pathogenic one. In particular, neither the field PRRSV isolates nor the reference highly pathogenic strain gave rise to an IL-1beta response, which was consistently induced by the attenuated strain, only. This pattern of response was reversed in an inflammatory environment, in which the attenuated strain reduced the ongoing IL-1beta response. Results indicate that some pathogenic PRRSV strains can prevent a primary inflammatory response of PBMCs, associated with reduced permissiveness of mature macrophages for PRRSV replication in later phases.

Characterization of the IgA response to PRRS virus in pig oral fluids

Porcine Reproductive and Respiratory Syndrome (PRRS) is a complex model of host/virus relationship. Disease control measures often includes "acclimatization", i.e. the exposure of PRRS-naïve gilts and sows to PRRSV-infected pigs and premises before the breeding period. In this respect, we had repeatedly observed an association between PRRSV-specific IgA responses in oral fluids (OF) of gilts and block of PRRSV spread. Therefore, we set out to investigate in vitro the inhibition of PRRSV replication by OF samples with different titers of PRRSV-specific IgA and IgG antibody, using Real-time RT PCR. PRRSV yield reduction in monocyte-derived macrophages was associated with the IgA content in OF samples, whereas the IgG-rich samples were sometimes associated with antibody-dependent enhancement (ADE) of replication. Accordingly, we could discriminate between ADE-positive and ADE-negative PRRSV strains. Next, we separated Ig isotypes in OF samples of PRRSV-infected pigs by means of protein A and size exclusion chromatography. The above results were confirmed by using separated Ig isotypes. Both dimeric and monomeric IgA were associated with the strongest reduction of PRRSV replication. The treatment of pig macrophages with separated OF antibodies before PRRSV infection was also associated with PRRSV yield reduction, along with clear changes of both CD163 and CD169 surface expression. Our results point at a role of mucosal IgA in the control of PRRSV replication by extra- and/or intracellular interaction with PRRSV, as well as by induction of signals leading to a reduced susceptibility of macrophages to PRRSV infection.

Characterization of the blastogenic response to LPS of bovine peripheral blood mononuclear cells

Mitogens are diverse compounds of plant and microbial origin, widely employed to test immunocompetence in animals. The blastogenic response of bovine Peripheral Blood Mononuclear Cells (PBMC) to lypopolysaccharides (LPS) has been investigated in our laboratories for a long time. In particular, a possible correlation between blastogenic response to LPS and disease resistance of periparturient dairy cows had been observed in previous studies. Most important, low responder cows presented a higher frequency of disease cases after calving, compared with high responder animals. Owing to the above, different aspects of the blastogenic response to LPS were investigated on PBMC of healthy Friesian cows, using a 72-hour Bromodeoxyuridin (BrDU) cell proliferation assay. Stimulation with LPS induced little if any replication of bovine PBMC over 72 hours despite consistent BrDU detection in all the PBMC samples under study. Poor replication of LPS-stimulated PBMC was confirmed by cell cycle and cell growth flow cytometry analyses. In particular, LPS stimulation gave rise to very low percentages of S phase cells, sometimes lower than in control, unstimulated cells, as opposed to Concanavalin A-stimulated PBMC. Magnetic separation and analysis of BrDU-treated bovine PBMC after exposure to LPS showed that both B and CD4 T cells are involved in the blastogenic response to LPS, in contrast with current data based on human and murine models. Finally, LPS caused an early, specific up-regulation of TNF-α and TLR4 genes in bovine PBMC, and significant correlations were shown between the expression of inflammatory cytokine and Indoleamine-pyrrole 2,3-dioxygenase (IDO1) genes. On the whole, our data indicate that differences in the blastogenic response to LPS could be partly accounted for by heterogenicity of responding cells (B and T lymphocytes), which might also have an impact on induction and regulation of inflammatory responses and endotoxin tolerance.

Prime-boost vaccination with attenuated Salmonella Typhimurium ΔznuABC and inactivated Salmonella Choleraesuis is protective against Salmonella Choleraesuis challenge infection in piglets

Background

Salmonella enterica serovar Choleraesuis (S. Choleraesuis) infection causes a systemic disease in pigs. Vaccination could represent a solution to reduce prevalence in farms. In this study, we aimed to assess the efficacy of an attenuated strain of Salmonella enterica serovar Typhimurium (S. Typhimurium ΔznuABC) against S. Choleraesuis infection. The vaccination protocol combined priming with attenuated S. Typhimurium ΔznuABC vaccine and boost with an inactivated S. Choleraesuis vaccine and we compared the protection conferred to that induced by an inactivated S. Choleraesuis vaccine.

Methods

The first group of piglets was orally vaccinated with S. Typhimurium ΔznuABC and boosted with inactivated S. Choleraesuis, the second one was intramuscularly vaccinated with S. Choleraesuis inactivated vaccine and the third group of piglets was unvaccinated. All groups of animals were challenged with a virulent S. Choleraesuis strain at day 35 post vaccination.

Results

The results showed that the vaccination protocol, priming with S. Typhimurium ΔznuABC and boosted with inactivated S. Choleraesuis, applied to group A was able to limit weight loss, fever and organs colonization, arising from infection with virulent S. Choleraesuis, more effectively, than the prime-boost vaccination with homologous S. Choleraesuis inactivated vaccine (group B).

Conclusion

In conclusion, these research findings extend the validity of attenuated S. Typhimurium ΔznuABC strain as a useful mucosal vaccine against S. Typhimurium and S. Choleraesuis pig infection. The development of combined vaccination protocols can have a diffuse administration in field conditions because animals are generally infected with different concomitant serovars.

Infectious agents identified in aborted swine fetuses in a high-density breeding area: a three-year study

Reproductive failure in sows is one of the most important factors affecting pig breeding. Many reproductive disorders are linked to both environmental factors and infectious agents. The goal of our study was to determine the presence of pathogens that are known to cause abortion, considering a set of conditioning factors, such as seasonality and pregnancy period. A large number of aborted fetuses (1,625 fetuses from 140 farms) from a high-density breeding area in northern Italy was analyzed for a period of 3 years. The pigs were diagnosed based on direct (culture, PCR) or indirect (enzyme-linked immunosorbent assay) evidence. An infectious etiologic agent was found in 323 of 549 cases of abortion (58.8%). These included viral agents (Porcine circovirus-2, 138/323; Porcine reproductive and respiratory syndrome virus, 108/323; porcine parvovirus, 20/323; pseudorabies virus, 6/323; and Encephalomyocarditis virus, 3/323) and bacteria (Escherichia coli, 64/323; Streptococcus sp., 63/323; Staphylococcus sp., 5/323; Pasteurella sp., 3/323; Shigella sp., 1/323; and Yersinia sp., 1/323). This study describes the prevalence of infectious agents involved in reproductive failure in a high-density swine population. The data can be useful to swine breeders, practitioners, and medical specialists in monitoring animal health and in supervising the breeding process.

Salmonella enterica Serovar Typhimurium Exploits Inflammation to Modify Swine Intestinal Microbiota

Salmonella enterica serovar Typhimurium is an important zoonotic gastrointestinal pathogen responsible for foodborne disease worldwide. It is a successful enteric pathogen because it has developed virulence strategies allowing it to survive in a highly inflamed intestinal environment exploiting inflammation to overcome colonization resistance provided by intestinal microbiota. In this study, we used piglets featuring an intact microbiota, which naturally develop gastroenteritis, as model for salmonellosis. We compared the effects on the intestinal microbiota induced by a wild type and an attenuated S. Typhimurium in order to evaluate whether the modifications are correlated with the virulence of the strain. This study showed that Salmonella alters microbiota in a virulence-dependent manner. We found that the wild type S. Typhimurium induced inflammation and a reduction of specific protecting microbiota species (SCFA-producing bacteria) normally involved in providing a barrier against pathogens. Both these effects could contribute to impair colonization resistance, increasing the host susceptibility to wild type S. Typhimurium colonization. In contrast, the attenuated S. Typhimurium, which is characterized by a reduced ability to colonize the intestine, and by a very mild inflammatory response, was unable to successfully sustain competition with the microbiota.

Salmonella Typhimurium exploits inflammation to its own advantage in piglets

Salmonella Typhimurium (S. Typhimurium) is responsible for foodborne zoonotic infections that, in humans, induce self-limiting gastroenteritis. The aim of this study was to evaluate whether the wild-type strain S. Typhimurium (STM14028) is able to exploit inflammation fostering an active infection. Due to the similarity between human and porcine diseases induced by S. Typhimurium, we used piglets as a model for salmonellosis and gastrointestinal research. This study showed that STM14028 is able to efficiently colonize in vitro porcine mono-macrophages and intestinal columnar epithelial (IPEC-J2) cells, and that the colonization significantly increases with LPS pre-treatment. This increase was then reversed by inhibiting the LPS stimulation through LPS antagonist, confirming an active role of LPS stimulation in STM14028-intracellular colonization. Moreover, LPS in vivo treatment increased cytokines blood level and body temperature at 4 h post infection, which is consistent with an acute inflammatory stimulus, capable to influence the colonization of STM14028 in different organs and tissues. The present study proves for the first time that in acute enteric salmonellosis, S. Typhimurium exploits inflammation for its benefit in piglets.

Inactivated Salmonella enterica serovar Typhimurium monophasic variant (S. Typhimurium 1,4,[5],12:i-) in sows is effective to control infection in piglets under field condition

The monophasic variant of Salmonella enterica serovar Typhimurium, namely Salmonella 1,4,[5],12:i-, has been increasingly responsible for foodborne human cases of disease and is most frequently detected in pork, since the variant is widely spread in pig farms. The aim of this study was to assess the efficacy of an autologous vaccine in decreasing the prevalence of Salmonella 1,4,[5],12:i-, in pigs. The trial was performed in a multisite pig production system of Northern Italy. The autogenous vaccine was prepared from the Salmonella 1,4,[5],12:i- strain isolated from the clinical case occurring in the Farm. Different immunization protocols were applied, ranging from interventions only in sows or piglets, or both. Microbiological analysis was performed to assess faecal shedding in sows and their offspring from birth till end of the production cycle and organ colonization of slaughtered pigs. Body weight of pigs was recorded at different time-points. Humoral immune response was evaluated in serum samples of sows and piglets. S. Typhimurium 1,4,[5],12:i- determines reduction of animal growth and farm production, furthermore, contamination of carcasses at the slaughterhouse. The load of bacteria entering into the food processing chain is differently influenced by the regimen of administration of inactivated vaccine. In particular, a combined vaccination of sows and their offspring was able to improve the weight gain of growing pigs, to limit Salmonella colonization of organs and to reduce the number of carrier pigs, and hence lowering the risk of introducing Salmonella organisms in the slaughter process.

Parenteral administration of attenuated Salmonella Typhimurium ΔznuABC is protective against salmonellosis in piglets

A major cause of salmonellosis in humans is the contamination of pork products. Infection in pigs can be controlled using bio-security programs, but they are not sufficient in countries where a high level of infection is recorded. In this context, the use of vaccines can represent a valid supplementary method of control. Recently, we have demonstrated that an attenuated strain of Salmonella enterica serovar Typhimurium (Salmonella Typhimurium ΔznuABC) is protective against systemic and enteric salmonellosis in mouse and pig infection models, candidating this strain as an oral attenuated vaccine. In this study, we compared the efficacy of this attenuated Salmonella Typhimurium strain when administered orally or parenterally. Furthermore, in order to reproduce a pseudo-natural infection model, vaccinated pigs were allocated in the same pen with animals shedding virulent Salmonella Typhimurium. Animals were monitored weekly after vaccination and contact with infected piglets. Diarrhea and ataxia were recorded and Salmonella shedding was tested individually through bacterial culture. After four weeks of cohousing, piglets were euthanized, after which lymph nodes reactivity and gross lesions of the gut sections were scored at necropsy. Organs were submitted to microbiological and histological analyses. The data reported herein show that parenterally vaccinated animals do not shed the attenuated strain, and at the same time the absence of symptoms and decrease in virulent strain shedding in feces from day 6 after challenge demonstrated protection against infection induced by virulent Salmonella Typhimurium. In conclusion, our findings suggest that this is an alternative route of Salmonella Typhimurium ΔznuABC administration, without ignoring the advantages associated with oral vaccination.

Attenuated Salmonella enterica serovar Typhimurium lacking the ZnuABC transporter: an efficacious orally-administered mucosal vaccine against salmonellosis in pigs

We have recently demonstrated that an attenuated strain of Salmonella enterica serovar Typhimurium unable to synthesize the zinc transporter ZnuABC (S. Typhimurium ΔznuABC), is able to protect mice against systemic and enteric salmonellosis and is safe in pigs. Here, we have tested the protective effects of S. Typhimurium ΔznuABC in pigs. Resistance to challenge with the fully virulent strain S. Typhimurium ATCC 14028 was assessed in animals vaccinated with S. Typhimurium ΔznuABC (two dosages tested), in controls vaccinated with a formalin-inactivated virulent strain and in unvaccinated controls. Clinical signs of salmonellosis, faecal shedding and bacterial colonization of organs were used to assess vaccine-induced protection. After the challenge, pigs vaccinated with the attenuated S. Typhimurium ΔznuABC strain did not display clinical signs of salmonellosis (fever or diarrhoea). The vaccine also reduced intestinal tract colonization and faecal shedding of the fully virulent Salmonella strain, as compared to control groups. S. Typhimurium ΔznuABC represents a promising candidate vaccine against salmonellosis in pigs.

[Analysis of clinical pathway in changing and disabling neurological diseases]

Neurological diseases are characterized by the complexity of care and by a constant and changing disability. More and more frequently, their impact on the clinical pathway remains unknown. Seven postgraduate rehabilitation students (Master coordination du handicap, université Pierre-et-Marie-Curie, Paris) reconstructed the clinical pathway of 123 patients with various neurological diseases: multiple sclerosis, Alzheimer disease, amyotrophic lateral sclerosis, spinal trauma, Parkinson disease and brain tumors. There was a significant correlation between disease duration and the number of specialists involved in care, the number of prescribed drugs and the number of short-term hospitalizations; there was no correlation with age. This result suggests that with time an increasing number of complications related to the initial neurological disease developed. Hospitalization in rehabilitation units was highly correlated with the degree of disability and also with the help received by the patients during the course of their disease. This result suggests that these hospitalizations were a direct consequence of burn out among relatives. General practitioners (GP) were highly involved only during the initial part of the pathway, and their involvement rapidly declined thereafter, suggesting a probable relation with the specificities and the complexity of care for neurological diseases which induces a progressive transfer of responsibilities from the GP to the hospital. Social care was always incomplete and occurred too late during the course of the disease. The feeling by the patients that their care pathway was chaotic was highly correlated with the quality of the information given to the patient at the time of the announcement of their disease. This study confirms that cares for neurological diseases is highly specific and that expert centers and coordination networks are in a key position to ensure an efficient care pathway.

Salmonella Typhimurium lacking the Znuabc transporter is attenuated and immunogenic in pigs

Meat contamination by Salmonella spp. is emerging as a major cause of human enteric infections in industrialized countries. The attempts to reduce human cases of salmonellosis encompass pre- and post-harvest interventions. In this context, vaccination of pigs may represent an effective instrument in eliminating/reducing Salmonella burden through the food chain. We have previously demonstrated that Salmonella Typhimurium lacking the ZnuABC transporter (S. Typhimurium ΔznuABC) is a promising candidate live vaccine in different mouse models of Salmonella Typhimurium infection. In this study, we confirmed in pigs the attenuation of S. Typhimurium ΔznuABC. Moreover, we evaluated the safety and immunogenicity of S. Typhimurium ΔznuABC administered to pigs by the oral route. We monitored clinical conditions of animals and we conducted a microbiological culture and a quantification of the humoral and cellular immune response, respectively, on fecal and blood samples of pigs. After vaccination with attenuated S. Typhimurium ΔznuABC, pigs showed a modest degree of hyperthermia. In addition, fecal shedding of S. Typhimurium ΔznuABC could not be detected 28 days after the inoculum. Furthermore, vaccination with S. Typhimurium ΔznuABC elicited a distinct production of anti-Salmonella antibodies and IFN-γ. Taken together, these results suggest that S. Typhimurium ΔznuABC is attenuated and immunogenic in pigs. Although the vaccine dosages do not guarantee complete safety there is ample margin to set up better conditions of use, suggesting that S. Typhimurium ΔznuABC could be a promising attenuated strain to be used as live mucosal vaccine for oral delivery.

Creative discharge planning using the electronic medical record

A multidisciplinary continuous quality improvement (CQI) team at the authors' facility was commissioned and empowered to study and improve communication among the disciplines involved in discharge planning. CQI methods and tools were applied to analyze the process and determine the improvement. The authors of this article describe the use of a customized electronic medical record system to deliver accurate, rapid technology (DART) at their facility. DART was programmed to improve communication among the disciplines by assisting with the referral process. In addition, users are systematically prompted throughout the discharge process to ensure that all aspects are considered and documented.