Yersinia pestis, one of history’s deadliest pathogens, has killed millions over the course of human history. It has attributes that make it an ideal choice to produce mass casualties and is a prime candidate for use as a biological weapon. When aerosolized, Y. pestis causes pneumonic plague, a pneumonia that is 100% lethal if not promptly treated with effective antibiotics. Currently, there is no FDA approved plague vaccine. The current lead vaccine candidate, a parenterally administered protein subunit vaccine comprised of the Y. pestis virulence factors, F1 and LcrV, demonstrated variable levels of protection in primate pneumonic plague model. As the most likely mode of exposure in biological attack with Y. pestis is by aerosol, this raises a question of whether this parenteral vaccine will adequately protect humans against pneumonic plague. In the present study we evaluated two distinct mucosal delivery platforms for the intranasal (IN) administration of LcrV and F1 vaccine proteins, a live bacterial vector, Lactobacillus plantarum, and a tobacco mosaic virus (TMV) based delivery platform. IN administration of L. plantarum expressing LcrV, or TMV-conjugated to LcrV and F1 (TMV-LcrV+TMV-F1) resulted in the similar induction of high titers of IgG antibodies and evidence of proinflammatory cytokine secretion. However, only the TMV-conjugate delivery platform protected against subsequent lethal challenge with Y. pestis. TMV-LcrV+TMV-F1 co-vaccinated mice had no discernable morbidity and no mortality, while mice vaccinated with L. plantarum expressing LcrV or rLcrV+rF1 without TMV succumbed to infection or were only partially protected. Thus, TMV is a suitable mucosal delivery platform for an F1-LcrV subunit vaccine that induces complete protection against pneumonic infection with a lethal dose of Y. pestis in mice.

The laboratory diagnosis of Lyme disease is currently dependent on the detection of IgM and IgG antibodies against Borrelia burgdorferi, the causative agent of the disease. The significance of serum IgA against B. burgdorferi remains unclear. The production of intrathecal IgA has been noted in patients with the late Lyme disease manifestation, neuroborreliosis, but production of antigen-specific IgA during early disease has not been evaluated. In the current study, we assessed serum IgA binding to the B. burgdorferi peptide antigens, C6, the target of the FDA-cleared C6 EIA, and FlaB(211-223)-modVlsE(275-291), a peptide containing a Borrelia flagellin epitope linked to a modified VlsE sequence, in patients with early and late Lyme disease. Specific IgA was detected in 59 of 152 serum samples (38.8%) from early Lyme disease patients. Approximately 50% of early Lyme disease patients who were seropositive for peptide-specific IgM and/or IgG were also seropositive for peptide-specific IgA. In a subpopulation of patients, high peptide-specific IgA could be correlated with disseminated disease, defined as multiple erythema migrans lesions, and neurological disease complications. These results suggest that there may be an association between elevated levels of antigen-specific IgA and particular disease manifestations in some patients with early Lyme disease.

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Background QuantiFERON ELISA with Borrelia burgdorferi peptide antigens was previously shown to reliably detect IFN-γ in blood samples from adult patients with early Lyme disease and the response disappeared rapidly after treatment. We evaluated the response before and after appropriate antibiotic therapy in adolescent and adult subjects with more diverse stages of the illness. Methods Blood was obtained from clinician-identified Lyme disease patients with constitutional complaints, erythema migrans, nerve palsy, cardiac abnormality, or arthritis before (n = 68) and 6 weeks (n = 46) and 6 months (n = 45) after therapy. The sera were tested for Lyme disease by standard two-tiered testing (STTT) and anti-C6 antibodies by ELISA and the levels of IFN-γ in the blood samples were detected by QuantiFERON ELISA. Results A positive STTT result supported the clinical diagnosis of 37 (54%) subjects and anti-C6 antibodies were detected in 45 (66%) subjects, including 36 (97%) STTT-positive subjects, and the responses often persisted or expanded after antibiotic therapy. IFN-γ was detected in 49 (72%) subjects prior to treatment and the response most often significantly decreased 6 weeks (P = 0.007) or 6 months (P = 0.001) after treatment. Conclusions The QuantiFERON ELISA reliably detected IFN-γ in blood samples from adult and adolescent patients with varying stages of Lyme disease and the response disappeared rapidly after treatment. Additional studies to more critically evaluate clinical utility as a laboratory test for diagnosis and confirmation of effective therapy are warranted.

BackgroundThe sensitivity of current antibody detection assays against Borrelia burgdorferi in the early stage of Lyme disease is very low. In children especially, who commonly have febrile viral illnesses, manifestations of early Lyme disease can be misdiagnosed. We previously demonstrated that IFNγ secretion could be detected in whole blood collected from Lyme disease patients at first clinical presentation following overnight incubation of the blood with peptides derived from B. burgdorferi. In the present study, we further evaluated the utility of IFNγ release for the laboratory diagnosis of Lyme disease in children with varying stages of the illness.MethodsChildren ages 2–18 years with no prior history of Lyme disease and with manifestations of Lyme disease at any stage were enrolled in the study. Sick and healthy controls were enrolled for comparison. We collected history and physical examination data and blood samples at the time of enrollment, at 1 month, and at 6 months. Standard 2-tier testing with ELISA (whole cell sonicate [WCS] and C6) and western blot were run in parallel to the IFNγ release assay for all blood samples. Sensitivity and specificity of the study assay were determined for presentation at all stages of Lyme disease. Clinical data were summarized.ResultsBlood samples from 22 patients with Lyme disease and 7 controls (4 sick, 3 healthy) were obtained at the first visit. The IFNγ release assay detected early and early disseminated Lyme disease with 78% sensitivity compared with 59% sensitivity of 2-tier testing in our study. For patients presenting with a single erythema migrans (EM) lesion, the IFNγ release assay detected Lyme disease with 63% sensitivity compared with 14% sensitivity with 2-tier testing. The IFNγ release assay had only 25% sensitivity for detecting late disease. A single control patient was positive for both the IFNγ release assay and 2-tier serology.ConclusionA novel IFNγ release assay demonstrated significantly increased sensitivity when compared with 2-tier testing in the laboratory diagnosis of Lyme disease in patients presenting with a single EM lesion. Future study is needed to determine its utility in detecting early Lyme disease in patients with nonspecific febrile illness in the absence of erythema migrans.Disclosures R. Dattwyler, Qiagen: Collaborator, Research support. P. Arnaboldi, Qiagen: Collaborator, research materials.