Mutant Nmnat1 leads to a retina-specific decrease of NAD+ accompanied by increased poly(ADP-ribose) in a mouse model of NMNAT1-associated retinal degeneration.

Nicotinamide mononucleotide adenylyltransferase 1 (NMNAT1) is required for nuclear nicotinamide adenine mononucleotide (NAD+) biosynthesis in all nucleated cells, and despite its functional ubiquity, mutations in this gene lead to an isolated retinal degeneration. The mechanisms underlying how mutant NMNAT1 causes disease are not well understood, nor is the reason why the pathology is confined to the retina. Using a mouse model of NMNAT1-associated retinal degeneration that harbors the p.Val9Met mutation, we tested the hypothesis that decreased function of mutant NMNAT1 has a greater effect on the levels of NAD+ in the retina than elsewhere in the body. Measurements by liquid chromatography with tandem mass spectrometry showed an early and sustained decrease of NAD+ in mutant retinas that was not observed in other tissues. To understand how consumers of nuclear NAD+ are affected by the reduced availability of NAD+ in mutant retinas, poly(ADP-ribose) polymerase (PARP) and nuclear sirtuin activity were evaluated. PARP activity was elevated during disease progression, as evidenced by overproduction of poly(ADP-ribose) (PAR) in photoreceptors, whereas histone deacetylation activity of nuclear sirtuins was not altered. We hypothesized that PARP could be activated because of elevated levels of oxidative stress; however, we did not observe oxidative DNA damage, lipid peroxidation, or a low glutathione to oxidized glutathione ratio. Terminal deoxynucleotidyl transferase dUTP nick end labeling staining revealed that photoreceptors appear to ultimately die by apoptosis, although the low NAD+ levels and overproduction of PAR suggest that cell death may include aspects of the parthanatos cell death pathway.

CT can identify characteristic features of hypaxial muscle abscesses in dogs due to presumed migrating vegetal foreign material as well as additional changes along the migratory tract in other anatomic regions.

Hypaxial muscle abscess is an important differential in dogs presenting for abdominal or back pain, lameness, and nonspecific signs like fever, lethargy, and hyporexia. It can occur concurrently with intrathoracic disease such as pyothorax secondary to migrating vegetal foreign material. Twelve dogs that underwent CT of the lumbar spine or abdomen and had a diagnosed hypaxial abscess on surgical and/or microbiological examination were included in this retrospective, descriptive case series. Computed tomography findings and findings from other imaging modalities employed were described. Eleven dogs were hunting breeds. Clinical signs included lethargy, fever, increased respiratory effort, and abdominal or back pain. Radiography and/or ultrasonography were employed during preliminary work up at clinician discretion and respectively revealed changes consistent with osteomyelitis in the cranial lumbar vertebrae and heterogenous, hypoechoic areas in the hypaxial musculature consistent with abscesses. Computed tomography findings included enlargement of hypaxial muscles with well-defined fluid attenuating noncontrast enhancing areas with a contrast-enhancing rim consistent with abscesses, periosteal reaction and lysis of vertebrae, and retroperitoneal effusion. Four of the 12 cases in this series had material identified and removed at surgery. The other eight cases were presumed to be the same disease process based on compatible signalment, imaging findings, and microbiological results. Migrating vegetal foreign bodies are a common problem at the authors' institution. Computed tomography provided expedient, thorough visualization of the relevant hypaxial lesions for diagnostic and surgical planning purposes and also characterized intrathoracic components of this disease.

Artificial intelligence in veterinary diagnostic imaging: A literature review.

Artificial intelligence in veterinary medicine is an emerging field. Machine learning, a subfield of artificial intelligence, allows computer programs to analyze large imaging datasets and learn to perform tasks relevant to veterinary diagnostic imaging. This review summarizes the small, yet growing body of artificial intelligence literature in veterinary imaging, provides necessary background to understand these papers, and provides author commentary on the state of the field. To date, less than 40 peer-reviewed publications have utilized machine learning to perform imaging-associated tasks across multiple anatomic regions in veterinary clinical and biomedical research. Major challenges in this field include collection and cleaning of sufficient image data, selection of high-quality ground truth labels, formation of relationships between veterinary and machine learning professionals, and closure of the gap between academic uses of artificial intelligence and currently available commercial products. Further development of artificial intelligence has the potential to help meet the growing need for radiological services through applications in workflow, quality control, and image interpretation for both general practitioners and radiologists.

Metabolic Syndrome Identification in Patients Treated With Second-Generation Antipsychotic Medications.

The purpose of the current project was to assess missed opportunities to identify metabolic syndrome in patients treated with second-generation antipsychotic medication in a community hospital's inpatient psychiatric unit between January 1 and December 31, 2020. Data on demographics, metabolic syndrome risk factors, body mass index, medications, related diagnoses, and primary care providers (PCPs) were collected via retrospective chart review of 194 patients. This project used a nonexperimental design and heterogenous nonrandom convenience sample. Descriptive statistics, chi-square tests, one-tailed t tests, and binary logistic regression were used. The overall rate of metabolic syndrome was 47.4% (n = 92). A positive PCP status was significant for treatment with antihypertensives, statins, and antihyperglycemics (p < 0.05). Findings indicate the need to increase system-wide assessment of metabolic syndrome and integrate care coordination with PCPs. [Journal of Psychosocial Nursing and Mental Health Services, 60(8), 11-18.].

Implementation of a Discharge Education Program to Improve Transitions of Care for Patients at High Risk of Medication Errors.

Background: Transitions of care (TOC) points are those where patient outcomes can be affected, especially patients at high risk for medication errors. Pharmacist-led postdischarge telephone counseling positively affects patient outcomes, though challenges exist relating to successful patient contact. Objective: The objective of this study was to develop and evaluate a discharge education service bridging the inpatient and outpatient setting to increase successful patient contact points during the TOC process from hospital to home. Methods: This prospective, single-centered observational study examined the impact of a discharge medication education program on successful telephone follow-up contact. The primary outcome was the percentage of high-risk patients educated at hospital discharge who were successfully reached via follow-up telephone contact within 2 business days of discharge. Secondary end points included hospital readmission rates and patient survey responses. Results: A total of 50 patients were included in the initial evaluation of this service; 78% of patients were successfully contacted within 2 business days after discharge, an increase from a 20% success rate prior to service implementation. At follow-up telephone calls, patients reported taking an average of 16 medications. The 30-day readmission rate was 10% for patients receiving this service, compared with 19% prior to implementation. When asked if they understood the medication component of their care and if they found the TOC service to be satisfactory, 100% and 96% of patients strongly agreed or agreed with these statements, respectively, and none disagreed. Conclusion and Relevance: This service demonstrates how pharmacists can interact with a high-risk population and increase contact points to optimize care at crucial health care transition points.

Evaluation of the Impact of an Inpatient Hyperglycemia Protocol on Glycemic Control.

PURPOSE: Inpatient hyperglycemia is associated with poor outcomes. Existing research assessing inpatient hyperglycemia protocols has shown improvements in average blood glucose levels with inconsistent results regarding rates of hypoglycemia and hyperglycemia. The objective of this study was to evaluate the impact of an inpatient hyperglycemia protocol on glycemic control. METHODS: This retrospective cohort study at a large, community teaching hospital included adult patients in non-critical care units requiring insulin administration for glycemic control. The intervention examined was utilization of an inpatient hyperglycemia protocol, comprised of a computerized physician order entry order set and provider education at the time of implementation. Two cohorts, a pre-protocol implementation group and a post-protocol implementation group, were compared. The primary outcome was the incidence of blood glucose values within 70-180 mg/dL over a 72-hour period between groups. Key secondary outcomes included the incidence of hypoglycemia (less than 70 mg/dL), severe hyperglycemia (above 300 mg/dL), total insulin use, and hospital length of stay. RESULTS: The primary outcome was significantly improved following protocol implementation (54.2% vs. 58.4%, p = 0.001). Compared to the pre-protocol group, the post-protocol group had lower incidence of hypoglycemia (3.1% vs. 1.2%, p < 0.001), severe hyperglycemia (9.9% vs. 6.7%, p < 0.001), less total insulin use (1.1 units/kg vs. 0.6 units/kg, p < 0.001), and shorter length of stay (5.1 days vs. 3.7 days, p < 0.001). CONCLUSIONS: The implementation of an inpatient hyperglycemia protocol was associated with improved glycemic control, decreased incidence of both hypoglycemia and severe hyperglycemia, and less total insulin use.

Efficacy of Oral Vancomycin in Preventing Recurrent Clostridium difficile Infection in Patients Treated With Systemic Antimicrobial Agents.

We compared rates of recurrent Clostridium difficile infection in patients receiving or not receiving oral vancomycin prophylaxis with systemic antimicrobial therapy. The incidence of C. difficile infection was significantly lower in patients receiving prophylaxis (4.2% vs 26.6% in those without prophylaxis; odds ratio, 0.12; 95% confidence interval, .04-.4; P < .001).

Identification of Factors Impacting Recurrent Clostridium difficile Infection and Development of a Risk Evaluation Tool.

PURPOSE: Recurrent Clostridium difficile infection (RCDI) is a growing concern, yet limited data exists to clarify which patients are at highest risk.  Identification of these patients may better inform decisions of those who may benefit from prophylactic intervention. The purpose of this study was to determine which factors are associated with the recurrence of Clostridium difficile infection (CDI) and to develop a risk stratification tool.  Methods. Patients readmitted within 10 weeks of positive C. difficile polymerase chain reaction (PCR) with symptoms were included in this retrospective case control study.  The primary outcome was analyzed via univariate regression analyses of the independent factors including age, gender, number of CDI episodes, administration of acid blocking agents, antibiotics or chemotherapy, Charlson Comorbidity Index, gastrointestinal conditions, and exposure to healthcare facilities.  Results. Recurrent CDI was identified in 44 of 220 included patients.  In the univariate analysis, factors associated with development of RCDI included antibiotic exposure (OR 2.51, 95% CI 1.14-5.54; p 0.02) and inflammatory bowel disease (OR 5.77, 95% CI 1.24-26.79; p 0.03).  An evaluation tool was created from a well-fit model.  Additional factors included in the tool were chosen based on evaluation of findings from existing literature.  Conclusions. Antibiotic therapy and inflammatory bowel disease were found to be associated with RCDI.  Although a statistically significant association with RCDI was not found for other factors, this is likely related to small sample size.  The creation of an evaluation tool using specific patient factors can help determine the risk of RCDI, while future studies may validate this tool. This article is open to POST-PUBLICATION REVIEW. Registered readers (see "For Readers") may comment by clicking on ABSTRACT on the issue's contents page.

Human pluripotent stem cell modeling of alveolar type 2 cell dysfunction caused by ABCA3 mutations.

Mutations in ATP-binding cassette A3 (ABCA3), a phospholipid transporter critical for surfactant homeostasis in pulmonary alveolar type II epithelial cells (AEC2s), are the most common genetic causes of childhood interstitial lung disease (chILD). Treatments for patients with pathological variants of ABCA3 mutations are limited, in part due to a lack of understanding of disease pathogenesis resulting from an inability to access primary AEC2s from affected children. Here, we report the generation of AEC2s from affected patient induced pluripotent stem cells (iPSCs) carrying homozygous versions of multiple ABCA3 mutations. We generated syngeneic CRISPR/Cas9 gene-corrected and uncorrected iPSCs and ABCA3-mutant knockin ABCA3:GFP fusion reporter lines for in vitro disease modeling. We observed an expected decreased capacity for surfactant secretion in ABCA3-mutant iPSC-derived AEC2s (iAEC2s), but we also found an unexpected epithelial-intrinsic aberrant phenotype in mutant iAEC2s, presenting as diminished progenitor potential, increased NFκB signaling, and the production of pro-inflammatory cytokines. The ABCA3:GFP fusion reporter permitted mutant-specific, quantifiable characterization of lamellar body size and ABCA3 protein trafficking, functional features that are perturbed depending on ABCA3 mutation type. Our disease model provides a platform for understanding ABCA3 mutation-mediated mechanisms of alveolar epithelial cell dysfunction that may trigger chILD pathogenesis.

Intraoperative Ventilator Management of the Critically Ill Patient.

Strategies for the intraoperative ventilator management of the critically ill patient focus on parameters used for lung protective ventilation with acute respiratory distress syndrome, preventing or limiting the deleterious effects of mechanical ventilation, and optimizing anesthetic and surgical conditions to limit postoperative pulmonary complications for patients at risk. Patient conditions such as obesity, sepsis, the need for laparoscopic surgery, or one-lung ventilation may benefit from intraoperative lung protective ventilation strategies. Anesthesiologists can use risk evaluation and prediction tools, monitor advanced physiologic targets, and incorporate new innovative monitoring techniques to develop an individualized approach for patients.

Impact of Vitamin K Administration on Elevated International Normalized Ratio in Chronic Liver Disease.

Limited studies assess the efficacy of vitamin K administration in patients with chronic liver disease (CLD). However, vitamin K is commonly used to treat elevations in international normalized ratio (INR) in these patients with the intended benefit of reducing bleeding risk. This retrospective, single-center cohort study aimed to evaluate the impact of vitamin K administration on INR in patients with CLD. Hospitalized patients ≥ 18 years of age with a diagnosis of CLD or cirrhosis and received vitamin K were included. The primary outcome was the absolute change in INR from baseline to 24 to 48 h after vitamin K administration. Secondary endpoints included subgroup analyses of the primary outcome by route of administration and single versus multidose administration, and incidence of in-hospital venous thromboembolism (VTE) or major bleeding. A total of eighty-five patients, primarily with Child-Pugh class C (76.5%), were included. Route of vitamin K administration included oral (PO) (72%) and intravenous (IV) (26%) with a mean daily dose of 8.5 ± 2.3 mg. The absolute change in INR was -0.07 ± -0.35 following vitamin K administration. There was no difference in absolute INR change between single versus multiple dose administration (-0.16 ± -0.35 and -0.03 ± -0.35; P= .13) or between PO versus IV administration (-0.06 ± -0.23 and -0.18 ± -0.48; P = .11). The incidences of in-hospital VTE and major bleeding were 2.4% and 3.5%, respectively. The administration of vitamin K in hospitalized patients with CLD resulted in minimal INR change, suggesting this intervention may not have the intended benefit of reducing bleeding risk.

Evaluation of a Pharmacist-Driven Protocol for the Treatment of Opioid-Induced Constipation.

BACKGROUND: Opioid-induced constipation (OIC) treatment guidelines recommend over-the-counter laxatives as first-line therapy, followed by treatment with a peripherally-acting mu-opioid receptor antagonist (PAMORA) in refractory patients. OBJECTIVE: To evaluate the ability of a pharmacist-driven OIC protocol to promote increased scheduled laxative use prior to escalation to PAMORA therapy. METHODS: This retrospective, single-center cohort study evaluated patients 2 years pre- and post-protocol implementation. The primary outcome was the difference in the percentage of patients receiving 2 scheduled laxatives for ≥ 2 days prior to PAMORA therapy pre- and post-protocol. Secondary outcomes included difference in time to first bowel movement after PAMORA initiation, difference in total number of laxative/PAMORA doses administered, and difference in overall estimated total cost. Data was analyzed using chi-squared tests and Student's t tests. RESULTS: Three-hundred patients were included (150 patients in the pre and post-protocol groups). In the pre-protocol group, 53 patients (35%) received 2 scheduled laxatives for 2 days prior to naloxegol/methylnaltrexone compared to 96 patients (64%) in the postprotocol group (p < 0.0001). One-thousand twenty-one scheduled laxative doses were given pre-protocol versus 1625 doses post-protocol. Average time to first bowel movement was similar between groups (17.7 hours vs 16.0 hours p = 0.441). Estimated total cost of OIC reversal therapy decreased from $20,896.95 to $13,405.47. CONCLUSION: A pharmacist-driven OIC protocol is associated with an increase in the use of scheduled laxatives prior to PAMORA administration and decreased overall estimated total cost. A larger, prospective study is necessary to assess if this promotes more efficacious OIC.

Rimegepant: acute treatment for migraine headaches.

Migraine headache treatment is quickly evolving. There have been three new acute migraine treatment options (i.e., lasmiditan, rimegepant, ubrogepant) and four new preventive migraine treatment options (i.e., erenumab, fremanezumab, galcanezumab, eptinezumab) released in the past 3 years. The new migraine treatments are focusing on pathways within the newly, better understood neurovascular hypothesis that further describes the pathophysiology of migraine headaches in more detail than before. The discovery of vasoactive peptides, such as calcitonin gene-related peptide, has led to the development of many of these migraine agents. Rimegepant is one of these newly approved agents for acute migraine treatment in adults with or without aura. Rimegepant has been found to decrease pain and symptoms associated with migraine attacks and is generally well-tolerated.

Gene Therapy Preserves Retinal Structure and Function in a Mouse Model of NMNAT1-Associated Retinal Degeneration.

No treatment is available for nicotinamide mononucleotide adenylyltransferase 1 (NMNAT1)-associated retinal degeneration, an inherited disease that leads to severe vision loss early in life. Although the causative gene, NMNAT1, plays an essential role in nuclear nicotinamide adenine dinucleotide (NAD)+ metabolism in tissues throughout the body, NMNAT1-associated disease is isolated to the retina. Since this condition is recessive, supplementing the retina with a normal copy of NMNAT1 should protect vulnerable cells from disease progression. We tested this hypothesis in a mouse model that harbors the p.Val9Met mutation in Nmnat1 and consequently develops a retinal degenerative phenotype that recapitulates key features of the human disease. Gene augmentation therapy, delivered by subretinal injection of adeno-associated virus (AAV) carrying a normal human copy of NMNAT1, rescued retinal structure and function. Due to the early-onset profile of the phenotype, a rapidly activating self-complementary AAV was required to initiate transgene expression during the narrow therapeutic window. These data represent the first proof of concept for a therapy to treat patients with NMNAT1-associated disease.

Cytosine and adenine base editing of the brain, liver, retina, heart and skeletal muscle of mice via adeno-associated viruses.

The success of base editors for the study and treatment of genetic diseases depends on the ability to deliver them in vivo to the relevant cell types. Delivery via adeno-associated viruses (AAVs) is limited by AAV packaging capacity, which precludes the use of full-length base editors. Here, we report the application of dual AAVs for the delivery of split cytosine and adenine base editors that are then reconstituted by trans-splicing inteins. Optimized dual AAVs enable in vivo base editing at therapeutically relevant efficiencies and dosages in the mouse brain (up to 59% of unsorted cortical tissue), liver (38%), retina (38%), heart (20%) and skeletal muscle (9%). We also show that base editing corrects, in mouse brain tissue, a mutation that causes Niemann-Pick disease type C (a neurodegenerative ataxia), slowing down neurodegeneration and increasing lifespan. The optimized delivery vectors should facilitate the efficient introduction of targeted point mutations into multiple tissues of therapeutic interest.

Innate immune cell signatures in a BCWD-Resistant line of rainbow trout before and after in vivo challenge with Flavobacterium psychrophilum.

Phenotypes of myeloid-lineage cells remain poorly understood in the rainbow trout, and were the focus of this study, including effects of in vivo challenge to Flavobacterium psychrophilum (Fp), the cause of Bacterial Cold Water Disease (BCWD). A genetic line was used that is highly resistant to BCWD (R-line) as well as a susceptible control line (S-line). Using flow cytometry, we describe two Pax5-negative, myeloid-lineage populations: Population 1 consisted of small cells with high SSC and strong staining for Q4E, MPO, Pu1, EBF, and IL- 1ß, which we named "neutrophil-like" cell. Population 2 had high Q4E, but weaker MPO, Pu1, EBF, and IL-1ß staining. Five days after Fp-challenge, both genetic lines had a reduced abundance of neutrophil-like cells in anterior kidney, PBL, and spleen. Pop. 2 abundance was reduced in anterior kidney, and increased in spleen. S-line fish responded more strongly to Fp-challenge compared to R-line fish. Challenged fish with a higher abundance of neutrophil-like cells had significantly lower Fp-loads after challenge, suggesting that these cells aid in the resistance to BCWD.

A structured mentoring program to develop junior faculty into successful co-coordinators of a large multi-instructor pathophysiology course.

BACKGROUND AND PURPOSE: To develop and implement a system for junior clinical faculty to become successful course coordinators with the use of a mentoring program and ensure that student performance and satisfaction are maintained at a high level. EDUCATIONAL ACTIVITY AND SETTING: For five years, first-time faculty discussion group leaders in a required large (>225 students) multi-instructor pathophysiology course opted into a structured mentoring program for course coordination in the subsequent year. Program categories included course material development, exam and quiz management, discussion group management, and communication among students, faculty, and staff. FINDINGS: Mentors' previous coordination experience ranged from a few years to over a decade. Faculty participants included three second-year faculty. Each participant successfully undertook a full co-coordinator role the following year. Subsequently, each then became a lead mentor the following year for new participants. Exam quality/reliability statistics were sustained at a high level, course evaluations and student performance improved throughout the program, and all mentor/mentee reflections demonstrated a positive and impactful experience. DISCUSSION AND SUMMARY: Course coordination can be a small percentage of clinical faculty workload, yet is a significant time commitment. Pharmacy resident certificate or new faculty academy programs often do not include course coordination, which is a vital, higher level function/role. Structured mentoring early in professional career of junior faculty aids in the assumption of pedagogical leadership roles, while also developing mentoring skills of mid-level faculty.

Needle-guided ultrasound technique for axillary artery catheter placement in critically ill patients: A case series and technique description.

PURPOSE: Axillary arterial cannulation for blood pressure monitoring has been reported in adults since 1973. Reported failure rates using palpation landmarks are high. This report describes a needle-guided ultrasound technique for axillary arterial line placement in critically ill patients. METHODS: A retrospective review of all patients requiring axillary arterial cannulation attempts with ultrasound-assisted needle guidance for hemodynamic monitoring was performed from July 2010 to June 2016 at a single institution. RESULTS: One hundred fifty nine (159) cannulation attempts were performed in 155 patients. The overall success rate was 97%, with a first pass success rate of 84%. Inexperienced operators performed 49% of procedures under direct faculty supervision, and had a 99% success rate, which was not different from experienced operators. Almost 20% of patients had moderate-to-severe coagulopathy (platelets<50k/uL, INR>2.0 or PTT>60s). Complications reported included the following: nonfunctioning of catheter (6%) and hematoma (6%). Ischemia was noted in 2 patients (1%), but only one was attributed to the arterial catheter. CONCLUSIONS: Use of the needle-guided ultrasound assisted approach for axillary arterial line placement is easily teachable and can be used to promote safe and successful placement of axillary arterial lines for novice learners.

Comparison of hospital length of stay in patients treated with non-vitamin K oral anticoagulants or parenteral agents plus warfarin for venous thromboembolism.

OBJECTIVES: Existing research comparing hospital length of stay for patients treated with non-vitamin K oral anticoagulants or parenteral bridging to warfarin has been conducted primarily with the agent rivaroxaban. The objective of this study was to compare hospital length of stay between patients initiated on the non-vitamin K oral anticoagulants, apixaban or rivaroxaban, and patients initiated on parenteral anticoagulation agents plus warfarin for the treatment of venous thromboembolism. METHODS: A retrospective cohort study was conducted at an 859-bed, not-for-profit, teaching hospital. Adult patients admitted for a primary diagnosis of venous thromboembolism between 1 November 2012 and 31 August 2015 and treated with apixaban or rivaroxaban or a parenteral anticoagulant plus warfarin were included in the study. Eligible patients were identified using International Classification of Diseases, Ninth Revision codes for a primary diagnosis of acute thromboses and emboli and medication administration record data. Individuals using anticoagulation therapy prior to admission, released from the emergency department, or treated with thrombectomy or fibrinolytic therapy were excluded. RESULTS: A total of 152 patients were included in this study. Patient characteristics, including renal function, were similar between study arms. Venous thromboembolism treatment with apixaban or rivaroxaban compared to a parenteral anticoagulant plus warfarin was associated with a reduced hospital length of stay (2.63 vs 5.33 days; p < 0.05) and decreased total hospital cost adjusted to 2015 dollars (US$21,694 vs US$38,851; p = 0.013). CONCLUSION: These results suggest that treatment with a non-vitamin K anticoagulant may significantly reduce hospital length of stay and total hospital cost compared to a parenteral anticoagulant plus warfarin for patients admitted for venous thromboembolism.

A BCWD-resistant line of rainbow trout exhibits higher abundance of IgT+ B cells and heavy chain tau transcripts compared to a susceptible line following challenge with Flavobacterium psychrophilum.

Bacterial Cold Water Disease (BCWD) is a common, chronic disease in rainbow trout, and is caused by the gram-negative bacterium Flavobacterium psychrophilum (Fp). Through selective breeding, the National Center for Cool and Cold Water Aquaculture has generated a genetic line that is highly resistant to Fp challenge, designated ARS-Fp-R (or R-line), as well as a susceptible "control" line, ARS-Fp-S (S-line). In previous studies, resistance to Fp had been shown to correlate with naive animal spleen size, and further, naïve R-line trout had been shown to have a lower abundance of IgM+ and IgM++ cells compared to S-line fish. Here we wished to first determine whether the abundance of IgT+ and/or IgT++ cells differed between the two lines in naïve fish, and if so, how these patterns differed after in vivo challenge with Fp. Fp challenge was by intramuscular injection of live Fp and tissue collections were on days 5, 6, and/or 28 post-challenge, in two independent challenge experiments. Flow cytometric and gene expression analyses revealed that naïve R-line fish had a higher abundance of IgT+ B cells in their anterior kidney, spleen, and blood, compared to S line fish. Further, that after Fp challenge, this difference was maintained between the two lines. Lastly, abundance of IgT+ B cells and expression of secHCtau correlated with lower Fp pathogen loads in challenged fish. In the anterior kidney, IgM+ B cell abundance correlated with increased Fp loads. Together, these results suggest that IgT+ B lineage cells may have a protective function in the immune response to Fp.