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Objectives The purpose of this study was to examine outcomes after left ventricular assist device (LVAD) implantation in older adults (>75 years of age). Background An aging heart failure population together with improvements in mechanical circulatory support (MCS) technology have led to increasing LVAD implantations in older adults. However, data presenting age-specific outcomes are limited. Methods Adult patients in the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) who required durable MCS between 2008 and 2017 were included. Patients were stratified by 4 age groups: 75 years of age. Kaplan-Meier survival estimates were used to assess post-LVAD outcomes, with log-rank testing used to compare groups. Univariate and multivariate cox proportional hazard regression models were used to determine predictors of survival and complications. Results A total of 20,939 individuals received an LVAD during the study period: 7,743 (37.0%) were Conclusions Despite careful selection of older adults for LVAD implantation, age remains a significant predictor of mortality. Higher bleeding and lower clotting risk in elderly patients with LVADs support the use of a less intense antithrombotic regimen in this unique population.

Borrelia burgdorferi was discovered to be the cause of Lyme disease in 1983, leading to seroassays. The 1994 serodiagnostic testing guidelines predated a full understanding of key B. burgdorferi antigens and have a number of shortcomings. These serologic tests cannot distinguish active infection, past infection, or reinfection. Reliable direct-detection methods for active B. burgdorferi infection have been lacking in the past but are needed and appear achievable. New approaches have effectively been applied to other emerging infections and show promise in direct detection of B. burgdorferi infections.

Background Babesia microti is a parasite that infects red blood cells (RBCs) in mammals. It is transmitted to humans by tick bites, transfusion, organ transplantation, and congenital acquisition. Although the Babesia natural history and seroprevalence in donors have been well described, gaps in knowledge relevant to transfusion remain. Study design and methods Mice were infected with dilutions of parasitized blood to address the minimal infectious dose and the kinetics of parasitemia by quantitative polymerase chain reaction (qPCR) and of antibodies by enzyme immunoassay. Results In immunocompetent DBA/2 mice infected with 100 parasitized RBCs (pRBCs) and in immunodeficient NSG mice infected with 63 pRBCs, parasitemia was detectable in five of five mice each. Peak parasitemia up to 2 × 107 pRBCs/mL at 2 to 3 weeks or 5 × 108 pRBCs/mL at 6 weeks was observed for DBA/2 and NSG mice, respectively. Protracted fluctuating parasitemia was observed for 8 months in DBA/2 mice, whereas NSG mice exhibited a high-plateau parasitemia. Antibody titers continued to increase until 6 to 18 weeks in DBA/2 mice and remained high through 6 months. This study also investigated the analytical performance of Babesia assays that detect parasite DNA or RNA using a blinded panel. A Babesia assay targeting parasite RNA was approximately 10-fold more sensitive compared to qPCR targeting DNA. Conclusion The mice in this study were highly susceptible to Babesia infection using as few as 1 to 2 log pRBCs and maintained chronic parasitemia. If the infectious dose in human transfusion recipients is comparably low, a highly sensitive assay targeting parasite RNA may safeguard the blood supply, particularly before antibody detection.

The cause of Lyme disease, Borrelia burgdorferi, was discovered in 1983. A 2-tiered testing protocol was established for serodiagnosis in 1994, involving an enzyme immunoassay (EIA) or indirect fluorescence antibody, followed (if reactive) by immunoglobulin M and immunoglobulin G Western immunoblots. These assays were prepared from whole-cell cultured B. burgdorferi, lacking key in vivo expressed antigens and expressing antigens that can bind non-Borrelia antibodies. Additional drawbacks, particular to the Western immunoblot component, include low sensitivity in early infection, technical complexity, and subjective interpretation when scored by visual examination. Nevertheless, 2-tiered testing with immunoblotting remains the benchmark for evaluation of new methods or approaches. Next-generation serologic assays, prepared with recombinant proteins or synthetic peptides, and alternative testing protocols, can now overcome or circumvent many of these past drawbacks. This article describes next-generation serodiagnostic testing for Lyme disease, focusing on methods that are currently available or near-at-hand.

Background: The impact of respiratory failure on patients undergoing left ventricular assist device (LVAD) implantation is not well understood, especially since these patients were excluded from landmark clinical trials. We sought to evaluate the associations between immediate preimplant and postimplant respiratory failure on outcomes in advanced heart failure patients undergoing LVAD implantation. Methods and Results: We included all patients in the Interagency Registry for Mechanically Assisted Circulatory Support who were implanted with continuous-flow LVADs from 2008 to 2016. Of the 16 362 patients who underwent continuous-flow LVAD placement, 906 (5.5%) required preimplant intubation within 48 hours before implantation, and 1001 (6.1%) patients developed respiratory failure within 1 week after implantation. A higher proportion of patients requiring preimplant intubation were Interagency Registry for Mechanically Assisted Circulatory Support profile 1, required mechanical circulatory support, and presented with cardiac arrest or myocardial infarction ( P P P =0.001). After multivariable analysis, both preimplant intubation (hazard ratio, 1.20 [95% CI, 1.03–1.41]; P =0.021) and respiratory failure within 1 week (hazard ratio, 2.54 [95% CI, 2.26–2.85]; P Conclusions: Respiratory failure both before and after LVAD implantation identifies an advanced heart failure population with significantly worse 1-year mortality. This data might be helpful in counseling patients and their families about expectations about life with an LVAD.

Background Babesia, a tick-borne genus of intraerythrocytic parasites, is understudied in humans outside of established high-endemic areas. There is a paucity of data on Babesia in Africa, despite evidence that it is regionally present. A pilot study suggested that Babesia was present in a rural district of Tanzania. Methodology/Principal findings A cross-sectional study was conducted July-August 2017: residents in a case hamlet that had clustering of subjects with high signal-to-cut off (S/CO) ratios for antibodies against B. microti in the pilot study, and a control hamlet that had lacked significant signal, were evaluated for B. microti. Subjects aged ≥15yrs (n = 299) underwent clinical evaluation and household inspections; 10ml whole blood was drawn for Babesia transcription mediated amplification (TMA), B. microti indirect fluorescent antibody testing (IFA) and rapid diagnostic testing (RDT) for Plasmodium spp. Subjects aged, Author summary Babesia, a family of tick-borne parasites, causes babesiosis, a disease that is very similar to malaria. Babesia species are globally ubiquitous yet understudied in humans outside of a few areas of the world, most notably in the United States. There is very little, published information on Babesia in humans in Africa. We conducted a study of two rural communities in Tanzania where earlier findings had suggested Babesia was present. Dedicated study teams visited households in the two communities to collect information about the residents’ health as well as factors that could pose risk of exposure to ticks and other infectious diseases. The residents of the two communities also had samples collected for Babesia evaluation. The test results revealed that a few of the residents had likely been exposed to Babesia in the past but were not actively infected at time of the assessment. The findings provide additional support for Babesia’s presence in human populations in Africa. This is important as Babesia infection can mimic other infections, notably malaria.

BACKGROUND Babesia microti is the foremost infectious risk to the US blood supply for which a Food and Drug Administration (FDA)-licensed test is unavailable for donation screening. Characterization of the antibody response to B. microti and correlation with parasitemia is necessary to guide screening and donor management policies. STUDY DESIGN AND METHODS During an FDA licensure trial, blood donors were prospectively screened (July-November 2013) using a B. microti-specific antibody enzyme immunoassay (EIA, Immunetics) in highly endemic (New York [NY]; n = 13,688), moderately endemic (Minnesota [MN]; n = 4583), and nonendemic (New Mexico [NM]; n = 8451) regions. Blood donors with repeat-reactive (RR) results participated in a 12-month prospective cohort study using B. microti EIA, immunofluorescent assay, polymerase chain reaction (PCR), blood smear, and clinical questionnaire. RESULTS Thirty-seven (61.67%; 24 NY, seven MN, six NM) of 60 eligible RR donors enrolled in the study; 20 of 37 (54%) completed the 12-month follow-up visit of which 15 (75%) were still seroreactive. Nine PCR-positive donors were identified during index screening; five participated in the follow-up study, three were PCR positive at 6 months, and two remained positive at final follow-up (378 and 404 days). Most RR donors displayed low-level seroreactivity that was either stable or waning during follow-up. The level and pattern of reactivity correlated poorly with PCR positivity. CONCLUSION The findings indicate prolonged seropositivity in blood donors. Although rare, asymptomatic, persistent PCR positivity supports the current policy of indefinite deferral for donors with a history of babesiosis or positive test results. Repeat testing by PCR and serology will be necessary if reinstatement is to be considered.

Multiple methodologies have been used to detect antibodies to Babesia microti. Use of an indirect immunofluorescence assay (IFA) has been the most widely used approach, but IFAs have varied as to which antibody class or classes are being detected and in regard to cutoff titers. In this study, 245 different patients with polymerase chain reaction (PCR)–confirmed B. microti infection were tested by a polyvalent IFA using serum collected within 3 days of the date the blood sample for PCR testing was obtained. Of the 245 patients, 243 (99.2%) had a positive serologic test result (i.e., ≥1:64). Of the 243 patients who were seropositive, 242 (99.6%) had a titer of ≥1:256, 236 (97.1%) had a titer of ≥1:512, and 210 (86.4%) had a titer of ≥1:1024. In conclusion, high titer seropositivity based on a polyvalent IFA is to be expected at the time of PCR confirmation of active babesiosis in clinical practice.

Babesia is a tick-borne intraerythrocytic parasite that is clinically and diagnostically similar to malaria parasite, conferring risk of misdiagnosis in areas where both parasites are endemic. Data on Babesia in humans in Africa are lacking, despite evidence that it is present in regional animal populations. Samples that were collected in November 2014 to July 2015 in Kilosa district, Tanzania, were evaluated for evidence of malaria and Babesia infection. Clinical data and laboratory samples (i.e., hemoglobin, rapid diagnostic testing [RDT] for malaria, peripheral blood smear, and dried blood spots) from a routine survey were available for analysis. Dried blood spots were tested using an investigational enzyme linked immunosorbent assay (ELISA) against Babesia microti. A total of 1,030 children aged 1 month to < 5 years were evaluated; 186 (18.1%) were malaria RDT positive, 180 (96.8%) of whom had peripheral smears reviewed; 70/180 (38.9%) were smear positive for parasites. The median (inter quartile range) and range of B. microti ELISA signal to cutoff (S/C) ratio was 0.10 (0.06-0.15) and 0.01-1.65, respectively; the S/C ratios were significantly higher in subjects ≥ 1 year as compared with those < 1 year old (P < 0.001). There was also a statistically significant association between a positive RDT for malaria and the Babesia S/C (median 0.09 versus 0.13 in RDT negative versus RDT positive, respectively; P < 0.001). The highest S/C ratios were disproportionately clustered in a few hamlets. The findings suggest that Babesia may be present in Kilosa district, Tanzania. However, serological cross-reactivity and false positivity, notably between Babesia and Plasmodium spp., cannot be definitively excluded and have implications for testing in other settings.

To diagnose Lyme disease, a two-tier testing algorithm is used in which supplemental IgM and IgG immunoblots to detect antibody to Borrelia burgdorferi are reflexively performed if a first-tier assay, such as a whole-cell sonicate-based enzyme immunoassay (WCS EIA), is reactive. Recent data suggest that equal specificity is found by substituting the C6 peptide EIA for immunoblots. In this study using 3956 control sera, we demonstrated that although this two-tier testing algorithm does significantly improve diagnostic specificity compared with each of the EIAs individually, the WCS EIA and the C6 peptide EIA are not independent tests. Therefore, when the C6 peptide EIA is used as the second-tier test, it should be regarded as a supplemental rather than a confirmatory test.

Babesia microti is a parasite that infects red blood cells (RBCs) in mammals. It is transmitted to humans by tick bites, transfusion, organ transplantation, and congenital acquisition. Although the Babesia natural history and seroprevalence in donors have been well described, gaps in knowledge relevant to transfusion remain.Mice were infected with dilutions of parasitized blood to address the minimal infectious dose and the kinetics of parasitemia by quantitative polymerase chain reaction (qPCR) and of antibodies by enzyme immunoassay.In immunocompetent DBA/2 mice infected with 100 parasitized RBCs (pRBCs) and in immunodeficient NSG mice infected with 63 pRBCs, parasitemia was detectable in five of five mice each. Peak parasitemia up to 2 × 10The mice in this study were highly susceptible to Babesia infection using as few as 1 to 2 log pRBCs and maintained chronic parasitemia. If the infectious dose in human transfusion recipients is comparably low, a highly sensitive assay targeting parasite RNA may safeguard the blood supply, particularly before antibody detection.

Importance Left ventricular assist devices (LVADs) improve outcomes in patients with advanced heart failure, but little is known about the role of neurohormonal blockade (NHB) in treating these patients. Objective To analyze the association between NHB blockade and outcomes in patients with LVADs. Design, Setting, and Participants This retrospective cohort analysis of the Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) included patients from more than 170 centers across the United States and Canada with continuous flow LVADs from 2008 to 2016 who were alive with the device in place at 6 months after implant. The data were analyzed between February and November 2019. Exposures Patients were stratified based on exposure to NHB and represented all permutations of the following drug classes: angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, β-blockers, and mineralocorticoid antagonists. Main Outcomes and Measures The outcomes of interest were survival at 4 years and quality of life at 2 years based on Kansas City Cardiomyopathy Questionnaire scores and a 6-minute walk test. Results A total of 12 144 patients in INTERMACS met inclusion criteria, of whom 2526 (20.8% ) were women, 8088 (66.6%) were white, 3024 (24.9%) were African American, and 753 (6.2%) were Hispanic; the mean (SD) age was 56.8 (12.9) years. Of these, 10 419 (85.8%) were receiving NHB. Those receiving any NHB medication at 6 months had a better survival rate at 4 years compared with patients not receiving NHB (56.0%; 95% CI, 54.5%-57.5% vs 43.9%; 95% CI, 40.5%-47.7%). After sensitivity analyses with an adjusted model, this trend persisted with patients receiving triple therapy with an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker, β-blocker, and mineralocorticoid antagonist having the lowest hazard of death compared with patients in the other groups (hazard ratio, 0.34; 95% CI, 0.28-0.41). Compared with patients not receiving NHB, use of NHB was associated with a higher Kansas City Cardiomyopathy Questionnaire score (66.6; bootstrapped 95% CI, 65.8-67.3 vs 63.0; bootstrapped 95% CI, 60.1-65.8;P = .02) and a 6-minute walk test (1103 ft; bootstrapped 95% CI, 1084-1123 ft vs 987 ft; bootstrapped 95% CI, 913-1060 ft;P Conclusions and Relevance Among patients with LVADs who tolerated NHB therapy, continued treatment was associated with improved survival and quality of life. The optimal heart failure regimen for patients after LVAD implant may be the initiation and continuation of guideline-directed medical therapy.

Babesiosis is a malaria-like illness caused by infection by members of the genus Babesia, a group of tick-borne intraerythrocytic protozoan parasites.1 Babesia microti is responsible for the overwhelming majority of human Babesia infections reported in the United States, where it is endemic in parts of the Northeast and upper Midwest. The parasite is primarily transmitted to humans through exposure to Ixodes scapularis (“deer ticks”) in endemic areas. However, B. microti is also readily transmissible by blood transfusion, and transfusion-transmitted babesiosis (TTB) is increasingly recognized as posing a risk to the blood supply.2,3 While B. microti infection results in asymptomatic or mild clinical findings in most immunocompetent hosts, infection in selected patient subsets, notably those who are immunosuppressed, asplenic, and/or at extremes of age, may lead to severe or even fatal disease.3,4 Overrepresentation of transfusion recipients among these high-risk groups accounts for the relatively high mortality ascribed to TTB.4,5 Currently, the only mandated strategy for TTB mitigation in use is a question regarding history of babesiosis posed directly to the potential donor before donation. The failure of this approach is evidenced by more than 150 cases of TTB that have been reported since 1979 with at least 12 fatalities since 2005.3 Despite being acknowledged as the foremost infectious risk to the US blood supply at present,5 there are as yet no validated, US Food and Drug Administration (FDA)-approved and commercially available tests for B. microti screening in blood donors. We report the development of a high-throughput enzyme immunoassay (EIA) that detects antibodies to B. microti, and B. microti seroreactivity was determined with this EIA in samples from New York Blood Center (NYBC) blood donors collected over a 4-month period in 2012. This pilot study was used to optimize the cutoff of the EIA and to validate the EIA and confirmatory algorithms before an FDA licensure trial launched in 2013.

The mainstay of laboratory diagnosis for Lyme disease is two-tiered serological testing, in which a reactive first-tier enzyme-linked immunosorbent assay (ELISA) or an immunofluorescence assay is supplemented by separate IgM and IgG immunoblots. Recent data suggest that the C6 ELISA can be substituted for immunoblots without a reduction in either sensitivity or specificity. In this study, the costs of 4 different two-tiered testing strategies for Lyme disease were compared using the median charges for these tests at 6 commercial diagnostic laboratories in 2012. The study found that a whole-cell sonicate ELISA followed by the C6 ELISA was the most cost-effective two-tiered testing strategy for Lyme disease with acute-phase serum samples. We conclude that the C6 ELISA can substitute for immunoblots in the two-tiered testing protocol for Lyme disease without a loss of sensitivity or specificity and is less expensive.

For the diagnosis of Lyme disease, the 2-tier serologic testing protocol for Lyme disease has a number of shortcomings including low sensitivity in early disease; increased cost, time, and labor; and subjectivity in the interpretation of immunoblots. In this study, the diagnostic accuracy of a single-tier commercial C6 ELISA kit was compared with 2-tier testing. The results showed that the C6 ELISA was significantly more sensitive than 2-tier testing with sensitivities of 66.5% (95% confidence interval [CI] 61.7-71.1) and 35.2% (95% CI 30.6-40.1), respectively (P < 0.001) in 403 sera from patients with erythema migrans. The C6 ELISA had sensitivity statistically comparable to 2-tier testing in sera from Lyme disease patients with early neurologic manifestations (88.6% versus 77.3%, P = 0.13) or arthritis (98.3% versus 95.6%, P = 0.38). The specificities of C6 ELISA and 2-tier testing in over 2200 blood donors, patients with other conditions, and Lyme disease vaccine recipients were found to be 98.9% and 99.5%, respectively (P < 0.05, 95% CI surrounding the 0.6 percentage point difference of 0.04 to 1.15). In conclusion, using a reference standard of 2-tier testing, the C6 ELISA as a single-step serodiagnostic test provided increased sensitivity in early Lyme disease with comparable sensitivity in later manifestations of Lyme disease. The C6 ELISA had slightly decreased specificity. Future studies should evaluate the performance of the C6 ELISA compared with 2-tier testing in routine clinical practice.

Purpose of review This review summarizes the current status of blood screening to prevent transfusion-transmitted babesiosis (TTB). Recent findings Babesia microti has recently been determined to be the most common transfusion-transmitted pathogen in the United States. Patients who acquire TTB often experience severe illness with an associated mortality rate of about 20%. Recent studies have demonstrated that laboratory screening using B. microti antibody and/or PCR assays can effectively identify infectious blood donors and that this approach may offer a cost- effective means of intervention. Pathogen inactivation methods may offer an alternative solution. None of these methods has yet been licensed by US Food and Drug Administration, however, and current efforts to prevent TTB rely on excluding blood donors who report having had babesiosis. Summary TTB imposes a significant health burden on the United States population. Further research is needed to better inform decisions on optimal screening strategies and reentry criteria, but given the acute need and the currently available screening tools, initiation of blood donor screening to prevent TTB should be given high priority.

We evaluated three diagnostic antigens (recombinant GP50, recombinant T24H, and synthetic Ts18var1) for cysticercosis and found that all three performed well in detecting cysticercosis in humans and pigs in several assay formats. These antigens were adapted to a new antibody detection format (QuickELISA). With one single incubation step which involves all reactants except the enzyme substrate, the QuickELISA is particularly suited for automation. We formatted the QuickELISA for the Triturus EIA analyzer for testing large numbers of samples. We found that in QuickELISA formats rGP50 and rT24H have better sensitivity and specificity than sTs18var1 for detecting porcine cysticercosis.

Detection of antibody to C6, a 26–amino acid peptide that reproduces the sequence of the sixth invariable region (IR6) within the central domain of the VlsE protein of Borrelia burgdorferi sensu lato, is currently used for the serologic diagnosis of Lyme disease [1–4]. A potential concern with a test based on a single peptide is the possibility of sequence variation and a consequent lack of antigenic cross-reactivity among pathogenic strains of B. burgdorferi sensu lato, leading to reduced diagnostic sensitivity in some infected patients. B. burgdorferi sensu stricto (hereafter referred to as B. burgdorferi) isolates can be categorized into 3 distinct ribosomal spacer restriction fragment length polymorphism genotypes (RSTs) on the basis of analysis of the 16S-23S ribosomal DNA (rDNA) spacer region [5, 6]. North American isolates of B. burgdorferi can also be differentiated into at least 16 major genetic groups on the basis of variability in the genetic sequence encoding outer surface protein C (OspC) [7, 8]. Studies employing these methods have demonstrated that pathogenicity is dependent at least in part on the genotype of B. burgdorferi causing the infection; for example, evidence indicates that RST1 and RST2 are more likely to be associated with hematogenous dissemination in humans than is RST3 [6]. Although serologic testing of patients with erythema migrans is not routinely recommended for the management of these patients, serum samples from such patients are often used to validate or compare serologic assays, because this is the most common manifestation of Lyme disease [9], and it is the only manifestation for which the diagnosis can frequently be confirmed by the microbiologic gold standard of recovering B. burgdorferi on culture [10]. In a previous study [11], we demonstrated the comparable sensitivity of a C6 assay in 79 patients from North America with erythema migrans, irrespective of the RST genotype that caused the infection. The current study expands on the previous study by increasing the number of patient serum samples evaluated and by also considering the ospC genotype of the infecting strain of B. burgdorferi. In addition, the effect of the genotype of B. burgdorferi on the sensitivity of 2-tier testing was evaluated.

BACKGROUND The tick-borne pathogen Babesia microti has become recognized as the leading infectious risk associated with blood transfusion in the United States, yet no Food and Drug Administration–licensed screening tests are currently available to mitigate this risk. The aim of this study was to evaluate the performance of an investigational enzyme immunoassay (EIA) for B. microti as a screening test applied to endemic and nonendemic blood donor populations. STUDY DESIGN AND METHODS The study aimed to test 20,000 blood donors from areas of the United States considered endemic for B. microti and 10,000 donors from a nonendemic area with the investigational B. microti EIA. Repeat-reactive samples were retested by polymerase chain reaction (PCR), blood smear, immunofluorescent assay (IFA), and immunoblot assay. In parallel, serum samples from symptomatic patients with confirmed babesiosis were tested by EIA, IFA, and immunoblot assays. RESULTS A total of 38 of 13,757 (0.28%) of the donors from New York, 7 of 4583 (0.15%) from Minnesota, and 11 of 8363 (0.13%) from New Mexico were found repeat reactive by EIA. Nine of the 56 EIA repeat-reactive donors (eight from New York and one from Minnesota) were positive by PCR. The specificity of the assay in a nonendemic population was 99.93%. Among IFA-positive clinical babesiosis patients, the sensitivity of the assay was 91.1%. CONCLUSION The B. microti EIA detected PCR-positive, potentially infectious blood donors in an endemic population and exhibited high specificity among uninfected and unexposed individuals. The EIA promises to provide an effective tool for blood donor screening for B. microti in a format amenable to high-throughput and cost-effective screening.

Although the current indirect immunofluorescent assay (IFA) diagnostic antibody test for human babesiosis is sensitive and specific, an immunoblot antibody test may be easier to standardize and to perform. Our objective, therefore, was to determine the efficacy of and develop interpretive criteria for an immunoblot antibody test for diagnosing acute human babesiosis using a Babesia microti whole-cell lysate as the antigen. We compared the reactivity of sera to a B. microti immunoblot assay in 24 human subjects experiencing symptoms and expressing laboratory evidence of babesiosis, 28 subjects who experienced Lyme disease, 12 subjects who experienced human granulocytic ehrlichiosis, and 51 subjects who reported no history of any of these diseases and whose sera did not react against B. microti antigen in an IFA test. Immunoblot strips were impregnated with proteins derived from the GI strain of B. microti that had been electrophoresed in an acrylamide sodium dodecyl sulfate gel, followed by electroblotting onto nitrocellulose membranes. The sera of all subjects who experienced babesiosis reacted against the B. microti antigen in the IFA and against at least one of nine immunoblot protein bands specific to B. microti . In contrast, none of the sera from people who appeared not to have experienced this infection reacted against the B. microti antigen in the IFA (compared to 4% in the immunoblot assay). When two reactive bands were considered as definitive, immunoblot test sensitivity was 96%, while specificity was 99% and predictive positivity and predictive negativity were 96 and 99%, respectively. Our B. microti immunoblot procedure shows promise as a sensitive, specific, and reproducible assay for routine clinical diagnosis of acute babesiosis.

Vaccine-induced seropositivity (VISP) or seroreactivity (VISR), defined as the reaction of antibodies elicited by HIV vaccines with antigens used in HIV diagnostic immunoassays, can result in reactive assay results for vaccinated but uninfected individuals, with subsequent misclassification of their infection status. The eventual licensure of a vaccine will magnify this issue and calls for the development of mitigating solutions in advance. An immunoassay that discriminates between antibodies elicited by vaccine antigens and those elicited by infection has been developed to address this laboratory testing need. The HIV Selectest is based on consensus and clade-specific HIV peptides that are omitted in many HIV vaccine constructs. The assay was redesigned to enhance performance across worldwide clades and to simplify routine use via a standard kit format. The redesigned assay was evaluated with sera from vaccine trial participants, HIV-infected and uninfected individuals, and healthy controls. The HIV Selectest exhibited specificities of 99.5% with sera from uninfected recipients of 6 different HIV vaccines and 100% with sera from normal donors, while detecting HIV-1 infections, including intercurrent infections, with 95 to 100% sensitivity depending on the clade, with the highest sensitivities for clades A and C. HIV Selectest sensitivity decreased in very early seroconversion specimens, which possibly explains the slightly lower sensitivity observed for asymptomatic blood donors than for clinical HIV cases. Thus, the HIV Selectest provides a new laboratory tool for use in vaccine settings to distinguish the immune response to HIV vaccine antigens from that due to true infection.

It has been proposed thatBorrelia burgdorferiinfection is present in ∼25% of children with autism spectrum disorders. In this study, antibodies againstBorrelia burgdorferiwere assessed in autistic (n= 104), developmentally delayed (n= 24), and healthy control (n= 55) children. No seropositivity againstBorrelia burgdorferiwas detected in the children with and without autism. There was no evidence of an association between Lyme disease and autism.

Background HIV Vaccine trials bring the significant risk of vaccineinduced HIV seropositivity(VISP) resulting in negative personal consequences for vaccinees. The overall rate of VISP in licensed EIA tests is reported as 41.7%(JAMA 2010;304:275-283). We have developed and modified the peptide-based HIV Selectest immunoassay(J.Virol 2006;80:2092-2099), which discriminates VISP from true HIV infection, in a format suitable for routine laboratory use, and have evaluated its performance on samples from three Phase III HIV vaccine trials.

Diagnosis of Taenia solium cysticercosis is an important component in the control and elimination of cysticercosis and taeniasis. New detection assays using recombinant and synthetic antigens originating from the lentil lectin-purified glycoproteins (LLGPs) of T. solium cysticerci were developed in a QuickELISA™ format. We analyzed a panel of 474 serum samples composed of 108 serum samples from donors with two or more viable cysts, 252 serum samples from persons with other parasitic infections, and 114 serum samples from persons with no documented illnesses. The sensitivities and specificities of T24H QuickELISA™, GP50 QuickELISA™, and Ts18var1 QuickELISA™ were 96.3% and 99.2%, 93.5% and 98.6%, and 89.8% and 96.4%, respectively, for detecting cases with multiple, viable cysts. T 24H QuickELISA™ performs best among the three assays, and has sensitivity and specificity values comparable to those of the LLGP enzyme-linked immunosorbent blot. The QuickELISA™ are simple, rapid quantitative methods for detecting antibodies specific for T. solium cysticerci antigens.

Scuba divers typically rinse equipment in communal tanks. Studies show these tanks are contaminated with bacteria, but the types of bacteria have not been studied. We sought to identify bacteria in rinse tanks at a dive facility at San Pedro, Belize, to determine the origin of the bacteria and determine whether the bacteria represented potential threats to human health. The identity of bacteria was investigated using reverse line blot (RLB) assays based on 28 different rDNA probes designed to detect known pathogens of sepsis, as well as by sequencing 23S rDNA from isolates and performing VITEK identification of several isolates. Based on the identities of bacteria in divers' rinse tanks, many likely originate from the ocean, and others likely originate from the divers themselves. None of the bacteria identified would be considered overt human pathogens. However, some of the bacteria found in the tanks are known to be associated with unsanitary conditions and can cause opportunistic infections, which may pose health problems to some individuals. Rinsing scuba equipment in communal tanks has the potential to transmit disease among some divers. Equipment, especially regulators and masks, should be rinsed/cleaned individually and not be placed in communal tanks.

Erythema migrans, the most common manifestation of Lyme disease, has been associated with highly variable rates of seropositivity for antibodies to Borrelia burgdorferi . Differences in the sensitivities of serologic assays for the detection of these antibodies, however, may not be the only or even the primary explanation for this observation. We investigated the impacts of four clinical variables on seropositivity—the duration of erythema migrans, the presence of single versus multiple skin lesions, and the gender and age of the patient. In this analysis, three different serologic tests were performed on acute-phase sera from 175 untreated patients with culture-confirmed erythema migrans: the C6 single-peptide enzyme-linked immunosorbent assay (ELISA), a commercially available ELISA in which a whole-cell sonicate of B. burgdorferi was the antigen, and a two-tier procedure. Irrespective of the serologic test performed, the results showed that seropositivity rates increased with the duration of the erythema migrans for patients with single lesions ( P < 0.001) but not for those with multiple skin lesions. The variability in seropositivity rates was greatest for the two-tier testing strategy, with a >6-fold-higher rate of seropositivity among patients with a single lesion of 22- to 30-day duration than among those whose skin lesion was of 1- to 7-day duration (85.7 versus 14.1%; P < 0.001). Rates of seropositivity by each of the testing methods were also significantly higher for patients with multiple skin lesions than for those with single lesions ( P < 0.001). In contrast, seropositivity rates were not affected by either the gender or the age of the patient. Thus, in patients with erythema migrans, certain clinical variables such as the duration and number of skin lesions had a profound impact on seropositivity rates, irrespective of the serologic assay performed.

We report the purification of a CaATPase of high specific activity from Paramecium tetraurelia. The enzyme is preferentially released into solution upon deciliation of cells by a Ca2+ shock procedure. Purification by ion exchange and gel filtration chromatography yields major peptides of 68 and 53 kDa and a minor peptide of 58 kDa, as determined by electrophoresis on sodium dodecyl sulfate polyacrylamide gels. These three peptides yield similar proteolytic peptide maps. Rabbit antisera to the purified enzyme inhibit enzyme activity and specifically label 68- and 53-kDa bands on nitrocellulose blots of the deciliation supernatant from which the enzyme is isolated. Concanavalin A-Sepharose precipitates about 60% of ATPase activity; only the 53-kDa band binds concanavalin A on nitrocellulose blots. The purified enzyme has a specific activity of 620 +/- 70 mumol/min/mg with ATP as substrate in the presence of Ca2+, which is required for enzyme activity. As substrates, ATP and GTP are strongly preferred to UTP and CTP. The Km for ATP in the presence of 3 mM Ca2+ is approximately 20 microM. Enzyme activity is strongly inhibited by the calmodulin antagonists trifluoperazine, fluphenazine, W7, and calmidazolium. However, calmodulin is not associated with the purified enzyme, based on the enzyme's inability to bind anti-calmodulin antibodies or to stimulate brain phosphodiesterase. The intracellular origin of this ATPase, its possible function, and its relationship to several other ATPases of Paramecium are discussed.

Protein 4.9, first identified as a component of the human erythrocyte membrane skeleton, binds to and bundles actin filaments1. Protein 4.9 is a substrate for various kinases, including a cyclic AMP(cAMP)-dependent one, in vivo and in vitro2–7. We show here that phosphorylation of protein 4.9 by the catalytic subunit of cAMP-dependent protein kinase reversibly abolishes its actin-bundling activity, but phosphorylation by protein kinase C has no such effect. A quantitative immunoassay showed that human erythrocytes contain 43,000 trimers of protein 4.9 per cell, which is equivalent to one trimer for each actin oligomer in these red blood cells. As analogues of protein 4.9 have been identified together with analogues of other erythroid skeletal proteins in non-erythroid tissues of numerous vertebrates8, phosphorylation and dephosphorylation of protein 4.9 may be the basis for a mechanism that regulates actin bundling in many cells.

Clathrin cages were isolated from rat erythrocytes. These structures exist in the intact cell as demonstrated by immunofluorescence and were not formed during the isolation procedure. The cages were largely devoid of membrane but contained the assembly protein complex and both the 50-kDa kinase (pp50) and casein kinase II activities found previously in clathrin-coated vesicles.

We present a new method for visualizing proteins electrophoresed in sodium dodecyl sulfate-polyacrylamide gels. After electrophoresis, gels are incubated in CuCl2 to produce a negative image of colorless protein bands against a semiopaque background. Gels are stained completely within 5 min, do not require destaniing, and can be stored indefinitely without loss of the image. Because proteins are not permanently fixed within the gel, they can be quantitatively eluted after chelation of Cu with EDTA. The sensitivity of the CuCl2 stain falls between that of Coomassie blue and silver. We anticipate that CuCl2 will be useful in the rapid analysis of proteins by polyacrylamide gel electrophoresis and in the preparation of purified polypeptides by elution from gel slices.