DNA immunization with in silico predicted T-cell epitopes protects against lethal SARS-CoV-2 infection in K18-hACE2 mice

The global SARS-CoV-2 pandemic caused significant social and economic disruption worldwide, despite highly effective vaccines being developed at an unprecedented speed. Because the first licensed vaccines target only single B-cell antigens, antigenic drift could lead to loss of efficacy against emerging SARS-CoV-2 variants. Improving B-cell vaccines by including multiple T-cell epitopes could solve this problem. Here, we show that in silico predicted MHC class I/II ligands induce robust T-cell responses and protect against severe disease in genetically modified K18-hACE2/BL6 mice susceptible to SARS-CoV-2 infection.

Preoperative urine culture is unnecessary in asymptomatic men prior to prostate needle biopsy

PURPOSE

To determine the clinical utility of preoperative urine cultures in asymptomatic men undergoing prostate needle biopsy (PNB).

METHODS

One hundred fifty asymptomatic men had urine cultures obtained 14-days prior to PNB. As per study protocol, positive cultures were not treated. Antibiotic prophylaxis prior to PNB included ciprofloxacin 500 mg the night before and morning of the biopsy. Repeat urine cultures were obtained immediately prior to PNB with colony-forming units (CFUs) annotated. Infectious complications post-biopsy were recorded.

RESULTS

Of the 150 men, six patients (4%) had evidence of asymptomatic bacteriuria with > 10,000 CFU/mL on office urine culture. Repeat urine cultures on morning of biopsy in all 150 patients noted a mean bacterial count of 55 CFU/mL (range 0-1000). All six patients with positive office urine cultures had < 100 CFU/mL at time of PNB. Following biopsy, four patients (2.7%) developed an infectious complication including two with sepsis and two with culture-positive UTIs. The causative organism in all cases was quinolone-resistant E. coli. None of the six patients with preoperative positive urine cultures developed an infectious complication following PNB.

CONCLUSIONS

In this prospective observational study, under 5% of asymptomatic men had positive office cultures prior to PNB. Furthermore, repeat urine culture on the morning of biopsy showed resolution in these patients, and none developed post-biopsy infectious complications. Routine office urine culture in the asymptomatic male prior to PNB was unnecessary.

Procedural povidone iodine rectal preparation reduces bacteriuria and bacteremia following prostate needle biopsy

INTRODUCTION

To determine if a povidone iodine rectal preparation (PIRP) reduces rates of bacteriuria and bacteremia following transrectal ultrasound guided prostate needle biopsy (TRUS PNB).

MATERIALS AND METHODS

Men undergoing TRUS PNB were prospectively enrolled in a study comparing the impact of PIRP versus standard of care (two pills of ciprofloxacin 500 mg). Urine, blood, and rectal cultures were obtained 30 minutes post-procedure with colony forming units (CFUs) determined after 48 hours. Patients were called 7 and 30 days post-procedure to evaluate for infections.

RESULTS

A total of 150 men were accrued into this study including 95 receiving PIRP and 55 the standard of care. Two-thirds of patients were undergoing an initial biopsy, 19% used antibiotics within the previous 6 months, and median number of biopsy cores was 14. There were no differences between the two cohorts with respect to baseline or biopsy characteristics. In the PIRP cohort, rectal cultures before and after PIRP administration noted a 97.2% reduction in microorganism colonies (2.4 x 10 5 CFU/mL versus 6.7 x 10³CFU/mL, p < 0.001). Mean urine bacterial counts following TRUS PNB were 1 CFU/mL for PIRP versus 7 CFU/mL for standard cohort (p < 0.001). Mean serum bacterial counts following TRUS PNB were 0 CFU/mL for PIRP versus 3 CFU/mL for standard of care (p = 0.01). One patient in the PIRP cohort (1.1%) developed post-biopsy sepsis while 3 (5.5%) in the standard cohort had an infectious complication (1 UTI, 2 sepsis).

CONCLUSION

A PIRP regimen reduced bacteruria and bacteremia following TRUS PNB.

Povidone Iodine Rectal Preparation at Time of Prostate Needle Biopsy is a Simple and Reproducible Means to Reduce Risk of Procedural Infection

Single institution and population-based studies highlight that infectious complications following transrectal ultrasound guided prostate needle biopsy (TRUS PNB) are increasing. Such infections are largely attributable to quinolone resistant microorganisms which colonize the rectal vault and are translocated into the bloodstream during the biopsy procedure. A povidone iodine rectal preparation (PIRP) at time of biopsy is a simple, reproducible method to reduce rectal microorganism colony counts and therefore resultant infections following TRUS PNB. All patients are administered three days of oral antibiotic therapy prior to biopsy. The PIRP technique involves initially positioning the patient in the standard manner for a TRUS PNB. Following digital rectal examination, 15 ml of a 10% solution of commercially available povidone iodine is mixed with 5 ml of 1% lidocaine jelly to create slurry. A 4 cmx4 cm sterile gauze is soaked in this slurry and then inserted into the rectal vault for 2 min after which it is removed. Thereafter, a disposable cotton gynecologic swab is used to paint both the perianal area and the rectal vault to a distance of 3 cm from the anus. The povidone iodine solution is then allowed to dry for 2-3 min prior to proceeding with standard transrectal ultrasonography and subsequent biopsy. This PIRP technique has been in practice at our institution since March of 2012 with an associated reduction of post-biopsy infections from 4.3% to 0.6% (p=0.02). The principal advantage of this prophylaxis regimen is its simplicity and reproducibility with use of an easily available, inexpensive agent to reduce infections. Furthermore, the technique avoids exposing patients to additional systemic antibiotics with potential further propagation of multi-drug resistant organisms. Usage of PIRP at TRUS PNB, however, is not applicable for patients with iodine or shellfish allergies.

Development of a novel tool for Francisella tularensis immunology (MUC1P.915)

Tularemia, an acute infection caused by Francisella tularensis, can manifest in various forms. Pulmonary tularemia developed after an aerosol exposure to the bacterium has a high risk of mortality in unvaccinated individuals. Therefore, development of a vaccine is of critcal importance but is hampered by a relative lack of understanding of the protective adaptive immune response. Absence of immunological tools to study protective T cell responses has been one of the key hurdles in establishing the profile of immune responses to F. tularensis. We have developed a novel F. tularensis LVS, which constitutively expresses a vgrG-OVA fusion protein containing the epitopes OVA257-264 and OVA323-339. This will allow researchers to study antigen-specifc T cell responses during infecton by F. tularensis. Robust expression of this construct was confirmed by immunoblot from bacterial lysates. An additional chromosomally-integrated expression construct is also being generated for more stable expression throughout in vivo infections. This new tool will allow us to study the memory response to Francisella vaccinaton in ways previously difficult to do. Inital experiments are underway using OT-I and OT-II transgenic mice to study the pathogen-specifc response to Francisella following vaccinaton by the intradermal and intranasal routes in order to determine the ideal conditons for improving survival after pulmonary challenge, which remains a concern in a potental bioterror atack.

Caspase-1-independent interleukin-1β is required for clearance of bordetella pertussis infections and whole-cell vaccine-mediated immunity (INM6P.413)

Whooping cough remains a significant disease worldwide and its re-emergence in highly vaccinated populations has been attributed to a combination of imperfect vaccines and evolution of the pathogen. The focus of this study was to examine the role of IL-1α/β and the inflammasome in generation of the interleukin-1 (IL-1) response, which is required for the clearance of B. pertussis. We show that IL-1β but not IL-1α is required for mediating the clearance of B. pertussis from the lungs of mice. We further found that IL-1β and IL-1R deficient mice have normal but persistent levels of inflammation, characterized by immune cell infiltration, with significantly increased IFNγ and a normal IL-17A response during B. pertussis infection. Contrary to expectations, the cleavage of precursor IL-1β to its mature form did not require caspase-1 during primary infections within the lung despite being required by bone marrow-derived macrophages exposed to live bacteria. We also found that the caspase-1 inflammasome was not required for protective immunity against a B. pertussis challenge following vaccination with heat-killed whole cell B. pertussis, despite IL-1R signaling being required. These findings demonstrate that caspase-1-independent host factors are involved in the processing of protective IL-1β responses that are critical for bacterial clearance and vaccine-mediated immunity.

Mice lacking IgA exhibit defective IgG antibody responses to polysaccharide conjugate vaccine (84.14)

Streptococcus pneumoniae is a leading cause of global disease. While capsular polysaccharide conjugate vaccines have decreased disease burden; a portion of the population remains unresponsive to vaccination. In order to understand the mechanisms responsible vaccine non-responsiveness, studies have been performed using mice with a targeted gene deletion that causes lack of IgA but few alterations in expression of other Ig isotypes. Surprisingly, IgA-/- mice were found nonetheless to exhibit specific defects in both IgA and IgG antibody responses to the polysaccharide (PS) component of pneumococcal conjugate vaccine. Neither IgM anti-PS responses nor IgG antibody responses to the protein component of the conjugate vaccine were affected. Furthermore, IgA-/- mice expressed fewer peritoneal B1a cells. As B1a and marginal zone B cells are considered to be the primary cell types that respond to polysaccharide antigens, this might to some extent explain the decreased anti-PS serum antibody titers seen in IgA-/- mice. Studies using bone marrow chimeras showed that reconstitution of IgA-/- mice with IgA+/+ B cells failed to restore antibody responsiveness to the PS component of the conjugate vaccine. Taken together, these results indicate that a defect in IgA expression affects B cell homeostasis, which is partially influenced by the environment that is present during B cell activation. (Supported by NIH grants RO1 41715 and R21 83878).

Modeling systems-level regulation of host immune responses

Many pathogens are able to manipulate the signaling pathways responsible for the generation of host immune responses. Here we examine and model a respiratory infection system in which disruption of host immune functions or of bacterial factors changes the dynamics of the infection. We synthesize the network of interactions between host immune components and two closely related bacteria in the genus Bordetellae. We incorporate existing experimental information on the timing of immune regulatory events into a discrete dynamic model, and verify the model by comparing the effects of simulated disruptions to the experimental outcome of knockout mutations. Our model indicates that the infection time course of both Bordetellae can be separated into three distinct phases based on the most active immune processes. We compare and discuss the effect of the species-specific virulence factors on disrupting the immune response during their infection of naive, antibody-treated, diseased, or convalescent hosts. Our model offers predictions regarding cytokine regulation, key immune components, and clearance of secondary infections; we experimentally validate two of these predictions. This type of modeling provides new insights into the virulence, pathogenesis, and host adaptation of disease-causing microorganisms and allows systems-level analysis that is not always possible using traditional methods.

The immune response is a complex network of processes activated in a host upon infection. Pathogens seek to disrupt or evade these processes to ensure their own survival and proliferation. This article provides a systems-level analysis of the immune response against two related bacterial species in the Bordetella genus, B. bronchiseptica and B. pertussis. B. pertussis, the causative agent of whooping cough, has lost many of the virulence factors of its B. bronchiseptica–like progenitor, and is using different strategies for the modulation of the immune system. We have synthesized two separate network models for the interaction of these pathogens with their hosts. Each network is then translated into a predictive dynamic model and is validated by comparison with available experimental data. The model offers predictions regarding cytokine regulation and the effects of perturbations of the immune system, as well as the time course of infections in hosts that had previously encountered the pathogens. We experimentally validate the prediction that convalescent hosts can rapidly clear both pathogens, while antibody transfer cannot substantially reduce the duration of a B. pertussis infection. This type of modeling provides new insights into the virulence, pathogenesis, and host adaptation of disease-causing microorganisms and can be readily extended to other pathogens.

Mucosal Immunopathogenesis of Francisella tularensis

Respiratory infection with Francisella tularensis is the deadliest form of disease and represents the most likely route to be used by bioterrorists. Although mucosal surfaces represent the first line of defense against respiratory tularemia, and in fact, against the great majority of human pathogens, little is known about protective immunity at these sites. The objective of this chapter is to review recent data examining the importance of various pulmonary immune mechanisms in defense against F. tularensis infection and to evaluate potential strategies for induction of protective lung immunity. Aerosol and intranasal mouse infection models have yielded essentially equivalent results and have implicated an important role for Th1-type immune responses in protection, including IFN-gamma, TNF-alpha, and IL-12. The cells responsible for protection in the lung are not well-characterized but NK cells are an early target for activation after infection although it appears that CD8 T cells might be most critical for host resistance. In addition, it is becoming increasingly clear that antibodies can provide prophylactic and therapeutic protection against pulmonary infection but only in the presence of active cell-mediated immunity. In fact, in vitro exposure of resting macrophages to antibody-coated bacteria in the absence of IFN-gamma can actually enhance infection. Although various immune mechanisms can be shown to be important for protection against attenuated strains such as LVS, the real challenge for the future is to design efficacious approaches to prevent disease by highly virulent strains such as SchuS4.