IMproving facial PRosthesis construction with contactlESs Scanning and Digital workflow (IMPRESSeD): study protocol for a feasibility crossover randomised controlled trial of digital versus conventional manufacture of facial prostheses in patients with orbital or nasal facial defects.

BACKGROUND: Facial prostheses can have a profound impact on patients' appearance, function and quality of life. There has been increasing interest in the digital manufacturing of facial prostheses which may offer many benefits to patients and healthcare services compared with conventional manufacturing processes. Most facial prosthesis research has adopted observational study designs with very few randomised controlled trials (RCTs) documented. There is a clear need for a well-designed RCT to compare the clinical and cost-effectiveness of digitally manufactured facial prostheses versus conventionally manufactured facial prostheses. This study protocol describes the planned conduct of a feasibility RCT which aims to address this knowledge gap and determine whether it is feasible to conduct a future definitive RCT. METHODS: The IMPRESSeD study is a multi-centre, 2-arm, crossover, feasibility RCT with early health technology assessment and qualitative research. Up to 30 participants with acquired orbital or nasal defects will be recruited from the Maxillofacial Prosthetic Departments of participating NHS hospitals. All trial participants will receive 2 new facial prostheses manufactured using digital and conventional manufacturing methods. The order of receiving the facial prostheses will be allocated centrally using minimisation. The 2 prostheses will be made in tandem and marked with a colour label to mask the manufacturing method to the participants. Participants will be reviewed 4 weeks following the delivery of the first prosthesis and 4 weeks following the delivery of the second prosthesis. Primary feasibility outcomes include eligibility, recruitment, conversion, and attrition rates. Data will also be collected on patient preference, quality of life and resource use from the healthcare perspective. A qualitative sub-study will evaluate patients' perception, lived experience and preference of the different manufacturing methods. DISCUSSION: There is uncertainty regarding the best method of manufacturing facial prostheses in terms of clinical effectiveness, cost-effectiveness and patient acceptability. There is a need for a well-designed RCT to compare digital and conventional manufacturing of facial prostheses to better inform clinical practice. The feasibility study will evaluate key parameters needed to design a definitive trial and will incorporate early health technology assessment and a qualitative sub-study to identify the potential benefits of further research. TRIAL REGISTRATION: ISRCTN ISRCTN10516986). Prospectively registered on 08 June 2021,  https://www.isrctn.com/ISRCTN10516986 .

Changes in Distal Tibial Microarchitecture During Eight Weeks of U.S. Army Basic Combat Training Differ by Sex and Race.

Basic combat training (BCT) is a physically rigorous period at the beginning of a soldier's career that induces bone formation in the tibia. Race and sex are determinants of bone properties in young adults but their influences on changes in bone microarchitecture during BCT are unknown. The purpose of this work was to determine the influence of sex and race on changes in bone microarchitecture during BCT. Bone microarchitecture was assessed at the distal tibia via high-resolution peripheral quantitative computed tomography at the beginning and end of 8 weeks of BCT in a multiracial cohort of trainees (552 female, 1053 male; mean ± standard deviation [SD] age = 20.7 ± 3.7 years) of which 25.4% self-identified as black, 19.5% as race other than black or white (other races combined), and 55.1% as white. We used linear regression models to determine whether changes in bone microarchitecture due to BCT differed by race or sex, after adjusting for age, height, weight, physical activity, and tobacco use. We found that trabecular bone density (Tb.BMD), thickness (Tb.Th), and volume (Tb.BV/TV), as well as cortical BMD (Ct.BMD) and thickness (Ct.Th) increased following BCT in both sexes and across racial groups (+0.32% to +1.87%, all p < 0.01). Compared to males, females had greater increases in Tb.BMD (+1.87% versus +1.40%; p = 0.01) and Tb.Th (+0.87% versus +0.58%; p = 0.02), but smaller increases in Ct.BMD (+0.35% versus +0.61%; p < 0.01). Compared to black trainees, white trainees had greater increases in Tb.Th (+0.82% versus +0.61%; p = 0.03). Other races combined and white trainees had greater increases in Ct.BMD than black trainees (+0.56% and + 0.55% versus +0.32%; both p ≤ 0.01). Changes in distal tibial microarchitecture, consistent with adaptive bone formation, occur in trainees of all races and sexes, with modest differences by sex and race. Published 2023. This article is a U.S. Government work and is in the public domain in the USA. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

A cross-over, randomised feasibility study of digitally printed versus hand-painted artificial eyes in adults: PERSONAL-EYE-S - a study protocol [version 2; peer review: 2 approved].

Background/objectives: Around 11,500 artificial eyes are required yearly for new and existing patients. Artificial eyes have been manufactured and hand-painted at the National Artificial Eye Service (NAES) since 1948, in conjunction with approximately 30 local artificial eye services throughout the country. With the current scale of demand, services are under significant pressure. Manufacturing delays as well as necessary repainting to obtain adequate colour matching, may severely impact a patient's rehabilitation pathway to a normal home, social and work life. However, advances in technology mean alternatives are now possible. The aim of this study is to establish the feasibility of conducting a large-scale study of the effectiveness and cost-effectiveness of digitally printed artificial eyes compared to hand-painted eyes. Methods: A cross-over, randomised feasibility study evaluating a digitally-printed artificial eye with a hand-painted eye, in patients aged ≥18 years with a current artificial eye. Participants will be identified in clinic, via ophthalmology clinic databases and two charity websites. Qualitative interviews will be conducted in the later phases of the study and focus on opinions on trial procedures, the different artificial eyes, delivery times, and patient satisfaction. Discussion: Findings will inform the feasibility, and design, of a larger fully powered randomised controlled trial. The long-term aim is to create a more life-like artificial eye in order to improve patients' initial rehabilitation pathway, long term quality of life, and service experience. This will allow the transition of research findings into benefit to patients locally in the short term and National Health Service wide in the medium to long term._. ISRCTN registration: ISRCTN85921622 (prospectively registered on 17/06/2021).

Cross-sectional study to describe bovine leukemia virus herd and within-herd ELISA prevalence and bovine leukemia virus proviral load of convenience-sampled Kansas beef cow-calf herds.

OBJECTIVE: Determine bovine leukemia virus (BLV) seroprevalence of adult female cattle in Eastern Kansas beef herds and the proviral load (PVL) of those cattle found to be ELISA positive. ANIMALS: Convenience sample of 2,845 cows from 44 beef herds. PROCEDURES: BLV serostatus was determined using an ELISA antibody test (gp-51; IDEXX). BLV quantitative PCR (qPCR) status and PVL were determined utilizing a qPCR test (SS1 qPCR test; CentralStar Laboratories). The association of age, herd size, and body condition score (BCS) category on the probability of being BLV positive was evaluated with a multiple variable logistic regression analysis that used BLV status as a binary outcome, herd nested within ranch as a random effect, and BCS, herd size, and age category as fixed effects. RESULTS: Forty-two of 44 herds had at least 1 BLV ELISA-positive cow (95.5% herd seroprevalence). Overall, 1,564 of the 2,845 cows were BLV ELISA positive (55.0% individual animal prevalence). No association between BLV ELISA status and herd size or BCS was identified. When evaluated by age, the model-adjusted probability of being BLV ELISA positive was lowest for heifers (1 year of age, first parity) and increased until 5 to 6 years of age. Of the 1,564 ELISA-positive animals, 838 were qPCR positive (53.6%). The model-adjusted probability of being qPCR positive was not associated with age, herd size, or BCS category. CLINICAL RELEVANCE: This study indicated that BLV-seropositive status both as a herd classification and individual animal classification was very common in this population. Because the percentage of BLV-seropositive cows varied between herds and by age, this study provides evidence that it is essential for investigators to control for herd and age in any analysis of the association of BLV serostatus and health and production outcomes of interest. Some BLV ELSIA-seropositive cows were classified as BLV negative by qPCR, and risk factors may differ between classification status by ELISA and qPCR.

The effect of bovine leukemia virus on dairy cow longevity.

Bovine leukemia virus (BLV) is a retrovirus of cattle that infects approximately 45% of all US dairy cattle, with about 90% of US dairy herds having at least one infected animal. Studies have found BLV infection to be associated with multiple measures of decreased immune function, which may explain the observed economic losses from milk production, decreased cow longevity, and predisposition to lymphoma and other diseases. Our objective was to measure the association between BLV infection and cow longevity in dairy cow operations. Ninety-one dairy herds from 9 US states volunteered to participate in this study. Milking dairy cows (n = 3,611) were tested for BLV antibodies using an ELISA milk test, and their presence in the herd was monitored for an average of 29 mo. The survival analysis controlled for herd and lactation number. Cows sold for dairy purposes were excluded, and individual cow results were not shared with producers so as not to influence culling decisions. Overall, 47.1% (1,701/3,611) of cows were BLV-positive by ELISA. The significant hazard ratio of 1.30 indicated that positive cows were 30% more likely than their negative herdmates to die or be culled during the monitoring period. These results are consistent with other studies in finding a negative effect of BLV infection on cow lifespan.

Identification of BoLA Alleles Associated with BLV Proviral Load in US Beef Cows.

Bovine leukemia virus (BLV) causes enzootic bovine leukosis, the most common neoplastic disease in cattle. Previous work estimates that 78% of US beef operations and 38% of US beef cattle are seropositive for BLV. Infection by BLV in a herd is an economic concern for producers as evidence suggests that it causes an increase in cost and a subsequent decrease in profit to producers. Studies investigating BLV in dairy cattle have noted disease resistance or susceptibility, measured by a proviral load (PVL) associated with specific alleles of the bovine leukocyte antigen (BoLA) DRB3 gene. This study aims to investigate the associations between BoLA DRB3 alleles and BLV PVL in beef cattle. Samples were collected from 157 Midwest beef cows. BoLA DRB3 alleles were identified and compared with BLV PVL. One BoLA DRB3 allele, *026:01, was found to be associated with high PVL in relation to the average of the sampled population. In contrast, two alleles, *033:01 and *002:01, were found to be associated with low PVL. This study provides evidence of a relationship between BoLA DRB3 alleles and BLV PVL in US beef cows.

Phenotypic Selection of Dairy Cattle Infected with Bovine Leukemia Virus Demonstrates Immunogenetic Resilience through NGS-Based Genotyping of BoLA MHC Class II Genes.

Characterization of the bovine leukocyte antigen (BoLA) DRB3 gene has shown that specific alleles associate with susceptibility or resilience to the progression of bovine leukemia virus (BLV), measured by proviral load (PVL). Through surveillance of multi-farm BLV eradication field trials, we observed differential phenotypes within seropositive cows that persist from months to years. We sought to develop a multiplex next-generation sequencing workflow (NGS-SBT) capable of genotyping 384 samples per run to assess the relationship between BLV phenotype and two BoLA genes. We utilized longitudinal results from milk ELISA screening and subsequent blood collections on seropositive cows for PVL determination using a novel BLV proviral load multiplex qPCR assay to phenotype the cows. Repeated diagnostic observations defined two distinct phenotypes in our study population, ELISA-positive cows that do not harbor detectable levels of provirus and those who do have persistent proviral loads. In total, 565 cows from nine Midwest dairy farms were selected for NGS-SBT, with 558 cows: 168 BLV susceptible (ELISA-positive/PVL-positive) and 390 BLV resilient (ELISA-positive/PVL-negative) successfully genotyped. Three BoLA-DRB3 alleles, including one novel allele, were shown to associate with disease resilience, *009:02, *044:01, and *048:02 were found at rates of 97.5%, 86.5%, and 90.3%, respectively, within the phenotypically resilient population. Alternatively, DRB3*015:01 and *027:03, both known to associate with disease progression, were found at rates of 81.1% and 92.3%, respectively, within the susceptible population. This study helps solidify the immunogenetic relationship between BoLA-DRB3 alleles and BLV infection status of these two phenotypic groupings of US dairy cattle.

Natural Infection of Dairy Cows with Bovine Leukemia Virus Affects Immunoglobulin Levels in Saliva and Serum but Not Milk.

Bovine leukemia virus (BLV) is a retroviral infection that disrupts the immune function of infected animals. It is widespread among U.S. dairy cattle. In this pilot study, the average total IgA and IgM concentrations in milk, saliva, and serum samples from BLV ELISA-positive (ELISA+) dairy cows were compared against samples from BLV ELISA-negative (ELISA-) cows using the Kruskal-Wallis test (with ties). The results from ELISA+ cows were also stratified by lymphocyte count (LC) and proviral load (PVL). In milk and saliva from ELISA+ cows, the average total IgA and IgM concentrations were decreased compared to ELISA- cows, although this was only statistically significant for saliva IgM in cows with low PVL (p = 0.0424). Numerically, the average total IgA concentrations were 33.6% lower in milk and 23.7% lower in saliva, and the average total IgM concentrations were 42.4% lower in milk and 15.5% lower in saliva. No significant differences were observed in the total serum IgA concentrations, regardless of PVL and LC. The total serum IgM from ELISA+ cows was significantly decreased (p = 0.0223), with the largest decreases occurring in the highest PVL and LC subgroups. This pilot study is a first step in investigating the impact of BLV on mucosal immunity and will require further exploration in each of the various stages of disease progression.

Characterizing the Cattle Gut Microbiome in Farms with a High and Low Prevalence of Shiga Toxin Producing Escherichia coli.

Cattle are the main reservoirs of Shiga toxin producing Escherichia coli (STEC), a major foodborne pathogen associated with acute enteric disease and hemolytic-uremic syndrome in humans. A total of 397 beef and dairy cattle from 5 farms were included in this study, of which 660 samples were collected for 16S rRNA gene sequencing. The microbiota of farms with a high-STEC prevalence (HSP) had greater richness compared to those of farms with a low-STEC prevalence (LSP). Longitudinal analyses showed STEC-shedders from LSP farms had higher microbiome diversity; meanwhile, changes in the microbiome composition in HSP farms were independent of the STEC shedding status. Most of the bacterial genera associated with STEC shedding in dairy farms were also correlated with differences in the percentage of forage in diet and risk factors of STEC carriage such as days in milk, number of lactations, and warm temperatures. Identifying factors that alter the gut microbiota and enable STEC colonization in livestock could lead to novel strategies to prevent fecal shedding and the subsequent transmission to humans.

Diagnostic Measures of Disease Progression in Cattle Following Natural Infection with Bovine Leukemia Virus.

This study describes the longitudinal changes in bovine leukemia virus (BLV) ELISA antibodies, proviral load (PVL), and blood lymphocyte counts (LC) observed over a 2.5-year period in naturally infected cattle. The dataset utilized was from a BLV intervention field trial on three Midwestern dairy herds. Our analysis showed ELISA false negatives were more likely to occur in cattle with low PVL and normal LC. On average, negligible changes in LC were observed during six-month intervals. Periods of lymphocytosis, defined as >10,000 lymphocytes per uL of blood, were observed in 31.5% (68/216) of BLV test-positive cattle. In BLV test-positive cows, an average increase of 2900 to 3100 proviral copies per 100,000 cells was observed during each subsequent six-month sampling interval. The difference between the minimum and maximum PVL observed for an ELISA-positive cow with 3 or more observations ranged from 0 to 115,600 copies per 100,000 cells (median: 12,900; mean: 19,200). Therefore, following the identification of ELISA-positive cattle and the assessment of PVL and LC, subsequent semiannual tests to assess disease progression may not be needed. Further work is needed to determine how available diagnostic tests can be optimized to design cost-effective testing schemes for BLV control programs.

Fracto-eutectogels: SDS fractal dendrites via counterion condensation in a deep eutectic solvent.

Glyceline, a deep eutectic solvent comprising glycerol and choline chloride, is a green nonaqueous solvent with potential industrial applications. Molecular mechanisms of surfactant self-assembly in deep eutectic solvents are expected to differ from those in their constituent polar components and are not well understood. Here we report the observation of self-assembled SDS fractal dendrites with dimensions up to ∼mm in glyceline at SDS concentrations as low as cSDS ∼ 0.1 wt%. The prevalence of these dendritic fractal aggregates led to the formation of a gel phase at SDS concentrations above ≥1.9 wt% (the critical gelation concentration cCGC). The gel microscopic structure was visualised using polarised light microscopy (PLM); rheology measurements confirmed the formation of a colloidal gel, where the first normal stress difference was negative and the elastic modulus was dominant. Detailed nano-structural characterisation by small-angle neutron scattering (SANS) further confirmed the presence of fractal aggregates. Such SDS aggregation or gelation has not been observed in water at such low surfactant concentrations, whereas SDS has been reported to form lamellar aggregates in glycerol (a component of glyceline). We attribute the formation of the SDS fractal dendrites to the condensation of counterions (i.e. the choline ions) around the SDS aggregates - a diffusion-controlled process, leading to the aggregate morphology observed. These unprecedented results shed light on the molecular mechanisms of surfactant self-assembly in deep eutectic solvents, important to their application in industrial formulation.

Digital photographic technique for the production of an artificial eye.

The use of hand painting an iris button using oil paint remains the conventional method of artificial eye manufacturing. The authors found that replacing this technique with a digital photograph taken of a patient's unaffected eye offers several advantages over the conventional method but the process from capture to print must be standardised and colour accurate. The authors of this paper suggest a tried and tested formulated photographic process of capture and printing prior to polymerisation. It discusses issues that can arise and how these can be overcome in order to achieve a high-quality print that can be used to produce a 'life like' ocular prosthesis.

Novel artificial eye service evaluation using patient reported outcome measures.

BACKGROUND: This service evaluation explores patient reported outcomes from patients provided with high definition ocular prostheses (artificial eyes). METHODS: Validated patient questionnaires (FACE-Q, DAS24 and HADS) were utilised to evaluate patient experiences of their new ocular prosthesis. 10 patients were included in the service evaluation, which was conducted between December 2018 and September 2019. Descriptive analysis of the mean and 95% CI was undertaken for all questionnaires. Statistical analysis was performed using SPSS 21 Principal Component Analysis (PCA) for FACE-Q questionnaires. Correlations were significant when factor loading is at α > 0.4. RESULTS: A questionnaire response rate of 80% was achieved (n = 8). PCA analysis showed the number of variables tested could be reduced. Two principal components (PC1 and PC2) had very good to excellent internal consistency between variables with factor loading (α = 0.7-0.9). PC1 contained questionnaires 1-7, all of which were highly correlated. PC2 contained question number 8 with a factor loading of α = 0.8. This indicates good reliability, validity and responsiveness. CONCLUSIONS: We hope to demonstrate the importance of service evaluations with respect to rapidly evolving technological advances in medical devices, pharmaceuticals and imaging modalities. Further feasibility and full clinical studies are required to confirm the positive results of the novel artificial eye service we have evaluated with respect to the traditional approach.

Current Developments in the Epidemiology and Control of Enzootic Bovine Leukosis as Caused by Bovine Leukemia Virus.

Enzootic Bovine Leukosis (EBL) caused by the bovine leukemia virus (BLV) has been eradicated in over 20 countries. In contrast, the U.S. and many other nations are experiencing increasing prevalence in the absence of efforts to control transmission. Recent studies have shown that BLV infection in dairy cattle has a greater impact beyond the long-recognized lymphoma development that occurs in <5% of infected cattle. Like other retroviruses, BLV appears to cause multiple immune system disruptions, affecting both cellular and humoral immunity, which are likely responsible for increasingly documented associations with decreased dairy production and decreased productive lifespan. Realization of these economic losses has increased interest in controlling BLV using technology that was unavailable decades ago, when many nations eradicated BLV via traditional antibody testing and slaughter methods. This traditional control is not economically feasible for many nations where the average herd antibody prevalence is rapidly approaching 50%. The ELISA screening of cattle with follow-up testing via qPCR for proviral load helps prioritize the most infectious cattle for segregation or culling. The efficacy of this approach has been demonstrated in at least four herds. Breeding cattle for resistance to BLV disease progression also appears to hold promise, and several laboratories are working on BLV vaccines. There are many research priorities for a wide variety of disciplines, especially including the need to investigate the reports linking BLV and human breast cancer.

Bovine leukemia virus detection and dynamics following experimental inoculation.

Bovine leukemia virus (BLV) infects more than 40% of the United States cattle population and impacts animal health and production. Control programs aiming to reduce disease prevalence and incidence depend on the ability to detect the BLV provirus, anti-BLV antibodies, and differences in blood lymphocyte counts following infection. These disease parameters also can be indicative of long-term disease progression. The objectives of this study were to determine the timing and to describe early fluctuations of BLV-detection by qPCR, ELISA, and lymphocyte counts. Fifteen Holstein steers were experimentally inoculated with 100 µL of a blood saline inoculum. Three steers served as in-pen negative controls and were housed with the experimentally infected steers to observe the potential for contract transmission. Five additional negative controls were housed separately. Steers were followed for 147 days post-inoculation (DPI). Infections were detected in experimentally infected steers by qPCR and ELISA an average of 24- and 36 DPI, respectively. Significant differences in lymphocyte counts between experimentally infected and control steers were observed from 30 to 45 DPI. Furthermore, a wide variation in peak proviral load and establishment was observed between experimentally infected steers. The results of this study can be used to inform control programs focused on the detection and removal of infectious cattle.

Impact of bovine leukemia virus infection on beef cow longevity.

Bovine leukosis is a chronic lymphoproliferative disorder caused by bovine leukemia virus (BLV). Previous studies estimate that 38 % of cow-calf beef herds and 10.3 % of individual beef cows in the US are BLV seropositive. About 70 % of BLV infected animals are asymptomatic carriers of the virus, while less than 5% develop lymphosarcoma, the leading reason for carcass condemnation at the US slaughterhouses. Studies provide evidence that BLV infection leads to decreased immune function making animals more vulnerable to other diseases, which could shorten their productive lifespan and increase economic losses in the cattle industry. BLV seropositive dairy cows are reportedly more likely to be culled sooner compared with their uninfected herd mates. Beyond simple prevalence studies, little is known about the impact of BLV infection in beef cattle production or specifically on beef cow longevity. Our objective was to determine the association between BLV infection and cow longevity in beef cow-calf operations. Twenty-seven cow-calf herds from the Upper Midwest volunteered to participate in this study. Female beef cattle (n = 3146) were tested for serum BLV antibodies by ELISA. A subsample of 648 cows were also tested for BLV proviral load (PVL). Culling data was collected for the subsequent 24 months. Twenty-one herds (77.7 %) had at least one BLV-infected animal, and 29.2 % (930/3146) of tested animals were BLV seropositive. Of the BLV-positive cows, 33.7 % (318/943) were culled compared with 32.1 % (541/1682) of the seronegative cows. BLV status did not affect cows' longevity within herds (P = 0.062). However, cows with high BLV PVL had decreased survival within the herd compared with ELISA- negative cows (P = 0.01). Overall, infection with BLV did not impact beef cow longevity unless the disease had progressed to a point of high BLV PVL.

The curious case of SDS self-assembly in glycerol: Formation of a lamellar gel.

HYPOTHESIS: Hydrogen-bonding capacities of polar nonaqueous media significantly affect self-assembly behaviours of surfactants in these media. INTRODUCTION: Glycerol, a nonaqueous hydrogen-bonding solvent, is widely used in industrial formulations due to its desirable physical properties. Surfactants are ubiquitous in such applications; however, surfactant self-assembly in glycerol is not well understood. METHODS: The microscopic structure of the gel phase was studied using a series of imaging techniques: polarised light microscopy (PLM), confocal laser scanning microscopy (CLSM), and environmental scanning electron microscopy (ESEM). The rheological properties of the gel were studied using viscometry and oscillation rheology measurements. Further nano-structural characterisation was carried out using small-angle neutron scattering (SANS). RESULTS: We have observed the unexpected formation of a microfibrillar gel in SDS and glycerol mixtures at a critical gelation concentration (CGC) as low as ~2 wt%; such SDS gelation has not been observed in aqueous systems. The microscopic structure of the gel consisted of microfibres some mm in length and with an average diameter of D ~ 0.5 µm. The fibres in the gel phase exhibited shear-induced alignment in the viscometry measurements, and oscillation tests showed that the gel was viscoelastic, with an elastic-dominated behaviour. Fitting to SANS profiles showed lamellar nano-structures in the gel microfibres at room temperature, transforming into cylindrical-micellar solutions above a critical gelation temperature, TCG ~ 45 °C. CONCLUSIONS: These unprecedented observations highlight the markedly different self-assembly behaviours in aqueous and nonaqueous H-bonding solvents, which is not currently well understood. Deciphering such self-assembly behaviour is key to furthering our understanding of self-assembly on a fundamental level.

Control of Bovine Leukemia Virus in Three US Dairy Herds by Culling ELISA-Positive Cows.

The objective of this trial was to evaluate a test-and-cull approach to controlling bovine leukemia virus (BLV) in US dairy herds with a low BLV prevalence. Despite worldwide distribution of the virus, 21 nations have eradicated BLV from their dairy cattle and are currently considered 'BLV-free.' In contrast, the US has attempted no industry-wide BLV control programs and has experienced an increase in BLV prevalence among dairy cows to about 40%. This raises concerns about production efficiency, herd health, and sustainability. In a pilot field trial with three Midwestern-US dairy herds, a test-and-cull approach using ELISA screening of milk samples was successful in reducing BLV prevalence in two herds. In the third herd, BLV prevalence increased following the introduction of infected heifers that were raised at an out-of-state calf raising facility. This trial demonstrated that a test-and-cull approach to BLV control can be successful in US dairy herds with low BLV prevalence, but ongoing surveillance is necessary to prevent reintroduction of the virus.

Breeding bulls as a potential source of bovine leukemia virus transmission in beef herds.

OBJECTIVE: To determine the prevalence of bovine leukemia virus (BLV) in beef bulls; evaluate the presence of BLV provirus DNA in blood, smegma, and semen samples; and analyze whether blood BLV proviral load was associated with differential blood cell counts. DESIGN: Observational cross-sectional study. ANIMALS: 121 beef bulls ≥ 2 years old from 39 Michigan herds. PROCEDURES: Blood, smegma, and semen samples were collected from each bull during a routine breeding soundness examination. An ELISA was used to detect serum anti-BLV antibodies. A coordination of common motifs-quantitative PCR assay was used to detect BLV provirus DNA in blood, smegma, and semen samples. Bulls with positive results on both the BLV serum ELISA and coordination of common motifs-quantitative PCR assay were considered infected with BLV. RESULTS: 19 of 39 (48.7%) herds and 54 of 121 (44.6%) bulls were infected with BLV. Provirus DNA was detected in the blood of all 54 and in smegma of 4 BLV-infected bulls but was not detected in any semen sample. Lymphocyte count was significantly greater in BLV-infected bulls than in uninfected bulls. The proportion of BLV-infected bulls with lymphocytosis (16/54 [29.6%]) was greater than the proportion of uninfected bulls with lymphocytosis (6/67 [9%]). Lymphocyte count was positively associated with BLV proviral load in BLV-infected bulls. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that almost half of beef bulls and herds were infected with BLV, and BLV provirus DNA was detected in the smegma of some BLV-infected bulls. Bulls may have an important role in BLV transmission in beef herds.