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A diagnostic investigation into an outbreak of fatal respiratory disease among young goats in Iowa, USA revealed bronchitis lesions of unknown etiology and secondary bacterial bronchopneumonia. Hypothesis-free metagenomics identified a previously unreported picornavirus (USA/IA26017/2023), and further phylogenetic analysis classified USA/IA26017/2023 as an aphthovirus related to bovine rhinitis B virus. Viral nucleic acid was localized to lesions of bronchitis using in situ hybridization. This marks the first report of a picornavirus putatively causing respiratory disease in goats and highlights the potential for cross-species transmission of aphthoviruses.

Introduction: The development of animal models of chronic liver disease via diet modification is a promising avenue for translational research but can lead to unexpected side effects that impact model adoption. While these side effects are well characterized in rodent models of nonalcoholic steatohepatitis (NASH), limited knowledge of these effects exists for novel porcine models of NASH. To close this gap, the present study investigates the side effects of diet-based NASH induction in pigs, with a systematic analysis of the pathologic mechanisms underlying dermatitis development and evaluation of treatment approaches., Method: Twelve pigs (10 large domestic pigs, 2 Goettingen minipigs) were fed a methionine- and choline-deficient, high-fat diet for 8 weeks to induce NASH. A retrospective review of each animal's clinical record was performed to identify the side effects of the diet. Following the identification of diet-associated dermatitis, severity was judged by using a novel gradation system that characterized the individual lesions and body regions resulting in a cumulative evaluation. In addition to this clinical assessment, the etiology of the dermatitis was investigated via histopathologic and microbiologic testing. Furthermore, the success of prophylactic and therapeutic treatment approaches was evaluated by considering dermatitis development and clinical course., Results: All study animals demonstrated unexpected side effects of the methionine- and choline-deficient, high fat diet. In addition to marked dermatitis, study pigs showed impaired weight gain and developed steatorrhea and anemia. Based on the skin gradation system, five animals developed severe dermatitis, four animals moderate dermatitis, and three animals mild diet-associated dermatitis. Histological and microbiological evaluation of the affected skin showed signs of a hypersensitivity reaction with secondary infection by bacteria and fungi. The analysis showed that preemptive bathing extended the lesion-free duration by nearly 20 days. Furthermore, bathing in combination with a targeted antibiotic treatment represented a helpful treatment approach for diet-associated dermatitis., Conclusion: The provision of a methionine- and choline-deficient, high fat diet represents an effective approach for inducing NASH liver disease in pigs but predisposes study animals to multiple side effects. These side effects are universal to animals on study but can be adequately managed and do not represent a significant limitation of this model., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Felgendreff, Lawrence, Hosseiniasl, Jacobs, Amiot, Felgendreff, Minshew, Sultan, Ahmadzada, Rahe and Nyberg.)

A total of 882 pigs (PIC TR4 × [Fast LW × PIC L02]; initially 33.2 ± 0.31 kg) were used in a 112-d study to evaluate the effects of different bones and analytical methods on the assessment of bone mineralization response to changes in dietary P, phytase, and vitamin D in growing pigs. Pens of pigs (20 pigs per pen) were randomized to one of five dietary treatments with nine pens per treatment. Dietary treatments were designed to create differences in bone mineralization and included: 1) P at 80% of NRC (2012) standardized total tract digestible (STTD) P requirement, 2) NRC STTD P with no phytase, 3) NRC STTD P with phytase providing an assumed release of 0.14% STTD P from 2,000 FYT/kg, 4) high STTD P (128% of the NRC P) using monocalcium phosphate and phytase, and 5) diet 4 with additional vitamin D3 from 25(OH)D3. On day 112, one pig per pen was euthanized for bone, blood, and urine analysis. Additionally, 11 pigs identified as having poor body condition which indicated a history of low feed intake (unhealthy) were sampled. There were no differences between treatments for final body weight, average daily gain, average daily feed intake, gain to feed, or bone ash measurements (treatment × bone interaction) regardless of bone ash method. The response to treatment for bone density and bone mineral content was dependent upon the bone sampled (density interaction, P = 0.053; mineral interaction, P = 0.078). For 10th rib bone density, pigs fed high levels of P had increased (P < 0.05) bone density compared with pigs fed NRC levels with phytase, with pigs fed deficient P, NRC levels of P with no phytase, and high STTD P with extra 25(OH)D3 intermediate, with no differences for metacarpals, fibulas, or 2nd ribs. Pigs fed extra vitamin D from 25(OH)D3 had increased (P < 0.05) 10th rib bone mineral content compared with pigs fed deficient P and NRC levels of P with phytase, with pigs fed industry P and vitamin D, and NRC P with monocalcium intermediate. Healthy pigs had greater (P < 0.05) serum Ca, P, vitamin D concentrations, and defatted bone ash than those unhealthy, with no difference between the two health statuses for non-defatted bone ash. In summary, differences between bone ash procedures were more apparent than differences between diets. Differences in bone density and mineral content in response to dietary P and vitamin D were most apparent with 10th ribs., (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Pigs from 64 commercial sites across 14 production systems in the Midwest United States were evaluated for baseline biological measurements used to determine bone mineralization. There were three pigs selected from each commercial site representing: 1) a clinically normal pig (healthy), 2) a pig with evidence of clinical lameness (lame), and 3) a pig from a hospital pen that was assumed to have recent low feed intake (unhealthy). Pigs ranged in age from nursery to market weight, with the three pigs sampled from each site representing the same age or phase of production. Blood, urine, metacarpal, fibula, 2nd rib, and 10th rib were collected and analyzed. Each bone was measured for density and ash (defatted and non-defatted technique). A bone × pig type interaction (P < 0.001) was observed for defatted and non-defatted bone ash and density. For defatted bone ash, there were no differences among pig types for the fibulas, 2nd rib, and 10th rib (P > 0.10), but metacarpals from healthy pigs had greater (P < 0.05) percentage bone ash compared to unhealthy pigs, with the lame pigs intermediate. For non-defatted bone ash, there were no differences among pig types for metacarpals and fibulas (P > 0.10), but unhealthy pigs had greater (P < 0.05) non-defatted percentage bone ash for 2nd and 10th ribs compared to healthy pigs, with lame pigs intermediate. Healthy and lame pigs had greater (P < 0.05) bone density than unhealthy pigs for metacarpals and fibulas, with no difference observed for ribs (P > 0.10). Healthy pigs had greater (P < 0.05) serum Ca and 25(OH)D3 compared to unhealthy pigs, with lame pigs intermediate. Healthy pigs had greater (P < 0.05) serum P compared to unhealthy and lame pigs, with no differences between the unhealthy and lame pigs. Unhealthy pigs excreted significantly more (P < 0.05) P and creatinine in the urine compared to healthy pigs with lame pigs intermediate. In summary, there are differences in serum Ca, P, and vitamin D among healthy, lame, and unhealthy pigs. Differences in bone mineralization among pig types varied depending on the analytical procedure and bone, with a considerable range in values within pig type across the 14 production systems sampled., (© The Author(s) 2024. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Background: Accurate measurement of disease associated with endemic bacterial agents in pig populations is challenging due to their commensal ecology, the lack of disease-specific antemortem diagnostic tests, and the polymicrobial nature of swine diagnostic cases. The main objective of this retrospective study was to estimate temporal patterns of agent detection and disease diagnosis for five endemic bacteria that can cause systemic disease in porcine tissue specimens submitted to the Iowa State University Veterinary Diagnostic Laboratory (ISU VDL) from 2017 to 2022. The study also explored the diagnostic value of specific tissue specimens for disease diagnosis, estimated the frequency of polymicrobial diagnosis, and evaluated the association between phase of pig production and disease diagnosis., Results: S. suis and G. parasuis bronchopneumonia increased on average 6 and 4.3%, while S. suis endocarditis increased by 23% per year, respectively. M. hyorhinis and A. suis associated serositis increased yearly by 4.2 and 12.8%, respectively. A significant upward trend in M. hyorhinis arthritis cases was also observed. In contrast, M. hyosynoviae arthritis cases decreased by 33% average/year. Investigation into the diagnostic value of tissues showed that lungs were the most frequently submitted sample, However, the use of lung for systemic disease diagnosis requires caution due to the commensal nature of these agents in the respiratory system, compared to systemic sites that diagnosticians typically target. This study also explored associations between phase of production and specific diseases caused by each agent, showcasing the role of S. suis arthritis in suckling pigs, meningitis in early nursery and endocarditis in growing pigs, and the role of G. parasuis, A. suis, M. hyorhinis and M. hyosynoviae disease mainly in post-weaning phases. Finally, this study highlighted the high frequency of co-detection and -disease diagnosis with other infectious etiologies, such as PRRSV and IAV, demonstrating that to minimize the health impact of these endemic bacterial agents it is imperative to establish effective viral control programs., Conclusions: Results from this retrospective study demonstrated significant increases in disease diagnosis for S. suis, G. parasuis, M. hyorhinis, and A. suis, and a significant decrease in detection and disease diagnosis of M. hyosynoviae. High frequencies of interactions between these endemic agents and with viral pathogens was also demonstrated. Consequently, improved control programs are needed to mitigate the adverse effect of these endemic bacterial agents on swine health and wellbeing. This includes improving diagnostic procedures, developing more effective vaccine products, fine-tuning antimicrobial approaches, and managing viral co-infections., (© 2023. The Author(s).)

A total of 360 pigs (DNA 600 × 241, DNA; initially 11.9 ± 0.56 kg) were used in a 28-d trial to evaluate the effects of different bones and analytical methods on the assessment of bone mineralization response to dietary P, vitamin D, and phytase in nursery pigs. Pens of pigs (six pigs per pen) were randomized to six dietary treatments in a randomized complete block design with 10 pens per treatment. Dietary treatments were designed to create differences in bone mineralization and included: (1) 0.19% standardized total tract digestibility (STTD) P (deficient), (2) 0.33% STTD P (NRC [2012] requirement) using monocalcium phosphate, (3) 0.33% STTD P including 0.14% release from phytase (Ronozyme HiPhos 2700, DSM Nutritional Products, Parsippany, NJ), (4) 0.44% STTD P using monocalcium phosphate, phytase, and no vitamin D, (5) diet 4 with vitamin D (1,653 IU/kg), and (6) diet 5 with an additional 50 µg/kg of 25(OH)D3 (HyD, DSM Nutritional Products, Parsippany, NJ) estimated to provide an additional 2,000 IU/kg of vitamin D3. After 28 d on feed, eight pigs per treatment were euthanized for bone (metacarpal, 2nd rib, 10th rib, and fibula), blood, and urine analysis. The response to treatment for bone density and ash was dependent upon the bone analyzed (treatment × bone interaction for bone density, P = 0.044; non-defatted bone ash, P = 0.060; defatted bone ash, P = 0.068). Thus, the response related to dietary treatment differed depending on which bone (metacarpal, fibula, 2nd rib, or 10th rib) was measured. Pigs fed 0.19% STTD P had decreased (P < 0.05) bone density and ash (non-defatted and defatted) for all bones compared to 0.44% STTD P, with 0.33% STTD P generally intermediate or similar to 0.44% STTD P. Pigs fed 0.44% STTD P with no vitamin D had greater (P < 0.05) non-defatted fibula ash compared to all treatments other than 0.44% STTD P with added 25(OH)D3. Pigs fed diets with 0.44% STTD P had greater (P < 0.05) defatted second rib ash compared to pigs fed 0.19% STTD P or 0.33% STTD P with no phytase. In summary, bone density and ash responses varied depending on bone analyzed. Differences in bone density and ash in response to P and vitamin D were most apparent with fibulas and second ribs. There were apparent differences in the bone ash percentage between defatted and non-defatted bone. However, differences between the treatments remain consistent regardless of the analytic procedure. For histopathology, 10th ribs were more sensitive than 2nd ribs or fibulas for the detection of lesions., (© The Author(s) 2023. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Bovine coronavirus (BCoV) is a known cause of enteric disease in cattle; however, its role in bovine respiratory disease (BRD) is poorly understood, with a dearth of evidence of the detection of the virus in respiratory tract lesions. We coupled histologic evaluation of tracheal and lower airway tissues from 104 calves with BRD in which BCoV was detected in the lungs via PCR followed by direct detection of BCoV by immunohistochemistry and an RNA in situ hybridization assay (ISH; RNAscope technology). RNAscope ISH detected BCoV in respiratory epithelium in more cases than did IHC. Using both methods of direct detection, tracheal epithelial attenuation and identification of the virus within lesions were observed commonly. Our results confirm a role of BCoV in respiratory tract infection and pathology, and show that the virus likely plays a role in the development of BRD.

Bovine Coronavirus (BCoV) is a member of a family of viruses associated with both enteric and respiratory diseases in a wide range of hosts. BCoV has been well-established as a causative agent of diarrhea in cattle, however, its role as a respiratory pathogen is controversial. In this study, fifteen calves were challenged intranasally with virulent BCoV in order to observe the clinical manifestation of the BCoV infection for up to 8 days after initial challenge, looking specifically for indication of symptoms, pathology, and presence of viral infection in the respiratory tract, as compared to six unchallenged control calves. Throughout the study, clinical signs of disease were recorded and nasal swabs were collected daily. Additionally, bronchoalveolar lavage (BAL) was performed at 4 days Post-challenge, and blood and tissue samples were collected from calves at 4, 6, or 8 days Post-challenge to be tested for the presence of BCoV and disease pathology. The data collected support that this BCoV challenge resulted in respiratory infections as evidenced by the isolation of BCoV in BAL fluids and positive qPCR, immunohistochemistry (IHC), and histopathologic lesions in the upper and lower respiratory tissues. This study can thus be added to a growing body of data supporting that BCoV is a respiratory pathogen and contributor to respiratory disease in cattle., Competing Interests: The authors and investigators for these studies are present or previous employees of Merck Animal Health., (Copyright © 2022 Soules, Rahe, Purtle, Moeckly, Stark, Samson and Knittel.)

To evaluate trends in bacterial causes of valvular endocarditis in swine, we retrospectively analyzed 321 cases diagnosed at Iowa State University Veterinary Diagnostic Laboratory (Ames, IA, USA) during May 2015--April 2020. Streptococcus gallolyticus was the causative agent for 7.59% of cases. This emerging infection in swine could aid study of endocarditis in humans.

Accurate and timely results of diagnostic investigations and laboratory testing guide clinical interventions for the continuous improvement of animal health and welfare. Infectious diseases can severely limit the health, welfare, and productivity of populations of animals. Livestock veterinarians submit thousands of samples daily to veterinary diagnostic laboratories (VDLs) for disease diagnosis, pathogen monitoring, and surveillance. Individual diagnostic laboratory reports are immediately useful; however, aggregated historical laboratory data are increasingly valued by clinicians and decision-makers to identify changes in the health status of various animal populations over time and geographical space. The value of this historical information is enhanced by visualization of trends of agent detection, disease diagnosis, or both, which helps focus time and resources on the most significant pathogens and fosters more effective communication between livestock producers, veterinarians, and VDL professionals. Advances in data visualization tools allow quick, efficient, and often real-time scanning and analysis of databases to inform, guide, and modify animal health intervention algorithms. Value is derived at the farm, production system, or regional level. Visualization tools allow client-specific analyses, benchmarking, formulation of research questions, and monitoring the effects of disease management and precision farming practices. We present here the approach taken to visualize trends of disease occurrence using porcine disease diagnostic code data for the period 2010 to 2019. Our semi-automatic standardized creation of a visualization platform allowed the transformation of diagnostic report data into aggregated information to visualize and monitor disease diagnosis.

Technologic advances in information management have rapidly changed laboratory testing and the practice of veterinary medicine. Timely and strategic sampling, same-day assays, and 24-h access to laboratory results allow for rapid implementation of intervention and treatment protocols. Although agent detection and monitoring systems have progressed, and wider tracking of diseases across veterinary diagnostic laboratories exists, such as by the National Animal Health Laboratory Network (NAHLN), the distinction between detection of agent and manifestation of disease is critical to improved disease management. The implementation of a consistent, intuitive, and useful disease diagnosis coding system, specific for veterinary medicine and applicable to multiple animal species within and between veterinary diagnostic laboratories, is the first phase of disease data aggregation. Feedback loops for continuous improvement that could aggregate existing clinical and laboratory databases to improve the value and applications of diagnostic processes and clinical interventions, with interactive capabilities between clinicians and diagnosticians, and that differentiate disease causation from mere agent detection, remain incomplete. Creating an interface that allows aggregation of existing data from clinicians, including final diagnosis, interventions, or treatments applied, and measures of outcomes, is the second phase. Prototypes for stakeholder cooperation, collaboration, and beta testing of this vision are in development and becoming a reality. We focus here on how such a system is being developed and utilized at the Iowa State University Veterinary Diagnostic Laboratory to facilitate evidence-based medicine and utilize diagnostic coding for continuous improvement of animal health and welfare.

The lack of available, well characterized, established, domestic porcine cell lines hinders the advancement of porcine cellular immunology. A case of multicentric lymphoma was diagnosed in a market weight pig at the time of slaughter. Affected lymph nodes and spleen were collected and used for single cell isolation and analysis. Cell lines were established by 3 rounds of limiting dilution from splenic and subiliac lymph node lymphomas. Surface marker staining identified the cells as CD21 + , CD79a + , CD20 + , PAX5 + , and CD3 - and cells were grown and easily passaged in cell culture. Transcriptome analysis was carried out to further characterize these rapidly proliferating cells validating the initial cytometric findings, confirming their identity as B cell lymphomas, and suggesting that they arose from germinal center centroblasts with aberrant control of BCL6 expression. Functional analysis identified the cells as being involved in cancer, cell movement, cell survival, and apoptosis. These new porcine B cell lymphoma cell lines will be a valuable resource for more in-depth cellular investigations into the porcine immune system and cancer, as well as providing a potential tool for the growth of lymphotropic viruses of pigs and humans., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Chondrosarcomas are common tumors of the canine appendicular and axial skeleton; however, extraskeletal chondrosarcomas are very rare. Herein we report a case of extraskeletal chondrosarcoma in the tongue of a dog. Histologically, glossal skeletal muscle was infiltrated and effaced by islands of cartilage and streams of spindle-shaped cells. Retrospective analysis of 236 tongue masses submitted to the Iowa State University surgical biopsy service between 2011 and 2019 showed that the majority of submitted tongue masses are either non-neoplastic or benign, with granular cell tumors identified as the most prevalent benign neoplasms. Malignant tumors accounted for nearly 30% of all submitted masses, with malignant melanoma diagnosed most frequently.

The increased prevalence of porcine group C rotavirus (PRVC) in suckling piglets and the emergence of new genetically distinct PRVC strains are concerning due to the associated significant economic losses they cause to the swine industry. We sequenced and analyzed two new PRVC strains, RV0104 (G3), and RV0143 (G6) and compared their pathogenesis with that of the historic strain Cowden (G1) in gnotobiotic (Gn) pigs. Near complete genome sequence analysis confirmed that these two strains were distinct from one another and the Cowden strain. VP1, VP2, VP6, NSP1-NSP3, and NSP5 genes were more similar between Cowden and RV0143, whereas VP3, VP7, and NSP4 shared higher nucleotide identity between Cowden and RV0104. Three-day-old and 3-week-old Gn piglets were inoculated with 10 5 FFU/piglet of Cowden, RV0104 or RV0143, or mock. All 3-day-old piglets developed severe diarrhea, anorexia, and lethargy, with mean PRVC fecal shedding titers peaking and numerically higher in RV0104 and RV0143 piglets on post infection day (PID) 2. Histopathological examination of the small intestine revealed that the 3-day-old Cowden and RV0104 inoculated piglets were mildly affected, while significant destruction of small intestinal villi was observed in the RV0143 inoculated piglets. Consistent with the highest degree of pathological changes in the small intestines, the RV0143 inoculated piglets had numerically higher levels of serum IL-17 and IFN-α cytokines and numerically lower PRVC IgA geometric mean antibody titers. Milder pathological changes and overall higher titers of PRVC IgA antibodies were observed in 3-week-old vs. 3-day-old piglets. Additionally, diarrhea was only observed in RV0104 and RV0143 (but not Cowden) inoculated 3-week-old piglets, while levels of serum IL-10 and PRVC IgA antibodies were higher in Cowden inoculated pigs, consistent with the lack of diarrhea. Thus, we confirmed that these current, genetically heterogeneous PRVC strains possess distinct pathobiological characteristics that may contribute to the increased prevalence of PRVC diarrhea in neonatal suckling piglets., (Copyright © 2020 Chepngeno, Takanashi, Diaz, Michael, Paim, Rahe, Hayes, Baker, Marthaler, Saif and Vlasova.)

Porcine reproductive and respiratory syndrome virus (PRRSV) is an important pathogen of swine health and well-being worldwide largely due to an insufficient understanding of the adaptive immune response to infection leading to ineffective PRRSV control. The memory and anamnestic response to infection are critical gaps in knowledge in PRRSV immunity. The lack of effective tools for the evaluation of the memory response previously hindered the ability to effectively characterize the porcine memory response to infection. However, the creation and validation of a PRRSV nsp7-specific B cell tetramer now facilitates the ability to detect very rare memory B cells and thus define the memory response of the pig. Here, we describe the PRRSV nsp7-specific B cell response following vaccination and challenge in six key secondary lymphoid organs including the identification of PBMCs as the tissue of interest for the memory immune response in pigs. Following live virus challenge of immune animals, an anamnestic response of nsp7-specific memory B cells and neutralizing antibodies was observed. This characterization of the functional humoral immune response to PRRSV answers key questions involved in regional specialization of the immune response following intramuscular inoculation of PRRSV MLV., (Copyright © 2020 Rahe, Dvorak, Patterson, Roof and Murtaugh.)

Vaccine control and prevention of porcine reproductive and respiratory syndrome (PRRS), the most important disease of swine, is difficult to achieve. However, the discovery of broadly neutralizing antibody activity against porcine reproductive and respiratory syndrome virus (PRRSV) under typical field conditions opens the door to new immunologic approaches for robust protection. We show here that passive administration of purified immunoglobulins with neutralizing antibodies reduced PRRSV2 infection by up to 96%, and PRRSV1 infection by up to 87%, whereas immune immunoglobulins lacking neutralizing activity had no effect on viral infection. Hence, immune competence of passive immunoglobulin transfer was associated specifically with antibody neutralizing activity. Current models of PRRSV infection implicate a minor envelope glycoprotein (GP) complex including GP2, GP3, and GP4, as critical to permissive cell infection. However, conserved peptides comprising the putative cell attachment structure did not attenuate neutralization or viral infection. The results show that immunological approaches aimed at induction of broadly neutralizing antibodies may substantially enhance immune protection against PRRSV. The findings further show that naturally occurring viral isolates are able to induce protective humoral immunity against unrelated PRRSV challenge, thus removing a major conceptual barrier to vaccine development., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Immunological memory is elicited after either vaccination or natural exposure to a pathogen and is essential for protection against re-exposure. Despite its critical importance, the ability to interrogate the veterinary animal memory immune response has long been hindered by a paucity of tools to assess immunological memory. As a result, the evaluation and analysis of protective immune responses that predict immune protection in food and fiber animals and facilitate vaccine development are obstructed. To fill this gap in knowledge in swine, we created a B cell tetramer to porcine reproductive and respiratory syndrome virus (PRRSV) nonstructural protein 7 (nsp7) to efficiently and effectively investigate the memory B cell response, a hallmark of anti-viral immunity. This novel reagent was validated by using a modified capture ELISA, tetramer pulldowns, and flow cytometry, and it was shown to detect rare, antigen-specific B cells that were present at a frequency of about 0.001% of total B lymphocytes in immune animals. The nsp7-B cell tetramer will help to characterize the PRRSV-specific memory B cell response, which is fundamentally important for understanding immunological competence and animal variation in resistance to PRRSV infection. We expect that the method will be widely applicable to the exploration of immunity to veterinary pathogens.

The adaptive immune response is necessary for the development of protective immunity against infectious diseases. Porcine reproductive and respiratory syndrome virus (PRRSV), a genetically heterogeneous and rapidly evolving RNA virus, is the most burdensome pathogen of swine health and wellbeing worldwide. Viral infection induces antigen-specific immunity that ultimately clears the infection. However, the resulting immune memory, induced by virulent or attenuated vaccine viruses, is inconsistently protective against diverse viral strains. The immunological mechanisms by which primary and memory protection are generated and used are not well understood. Here, we summarize current knowledge regarding cellular and humoral components of the adaptive immune response to PRRSV infection that mediate primary and memory immune protection against viruses.

Porcine reproductive and respiratory syndrome virus (PRRSV) continues to afflict swine nearly 30 years after it was first discovered as the causative agent of "mystery swine disease". Immunological tools of vaccination and exposure to virulent viruses have not succeeded in achieving control and prevention of PRRSV. Humoral immunity, mediated by antibodies, is a hallmark of anti-viral immunity, but little is known about the effector mechanisms of humoral immunity against PRRSV. It is essential to understand the immunological significance of antibody functions, including recently described broadly neutralizing antibodies and potential non-neutralizing activities, in the immune response to PRRSV. Here, we review recent research from PRRSV and other host-pathogen interactions to inform novel routes of exploration into PRRSV humoral immunity which may be important for identifying the immunological correlates of protection against PRRSV infection., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Immunological prevention of infectious disease, especially viral, is based on antigen-specific long-lived memory B cells. To test for cellular proliferation and differentiation factors in swine, an outbred model for humans, CD21+ B cells were activated in vitro with CD40L and stimulated with purported stimulatory cytokines to characterize functional responses. IL-21 induced a 3-fold expansion in total cell numbers with roughly 15% of all B cells differentiating to IgM or IgG antibody secreting cells (ASCs.) However, even with robust proliferation, cellular viability rapidly deteriorated. Therefore, a proliferation inducing ligand (APRIL) and B cell activating factor (BAFF) were evaluated as survival and maintenance factors. BAFF was effective at enhancing the viability of mature B cells as well as ASCs, while APRIL was only effective for ASCs. Both cytokines increased approximately two-fold the amount of IgM and IgG which was secreted by IL-21 differentiated ASCs. Mature B cells from porcine reproductive and respiratory virus (PRRSV) immune and naïve age-matched pigs were activated and treated with IL-21 and then tested for memory cell differentiation using a PRRSV non-structural protein 7 ELISPOT and ELISA. PRRSV immune pigs were positive on both ELISPOT and ELISA while naïve animals were negative on both assays. These results highlight the IL-21-driven expansion and differentiation of memory B cells in vitro without stimulation of the surface immunoglobulin receptor complex, as well as the establishment of a defined memory B cell culture system for characterization of vaccine responses in outbred animals., Competing Interests: The authors have declared that no competing interests exist.