Bivalent VSV Vectors Mediate Rapid and Potent Protection from Andes Virus Challenge in Hamsters

Orthohantaviruses may cause hemorrhagic fever with renal syndrome or hantavirus cardiopulmonary syndrome. Andes virus (ANDV) is the only orthohantavirus associated with human-human transmission. Therefore, emergency vaccination would be a valuable public health measure to combat ANDV-derived infection clusters. Here, we utilized a promising vesicular stomatitis virus (VSV)-based vaccine to advance the approach for emergency applications. We compared monovalent and bivalent VSV vectors containing the Ebola virus (EBOV), glycoprotein (GP), and ANDV glycoprotein precursor (GPC) for protective efficacy in pre-, peri- and post-exposure immunization by the intraperitoneal and intranasal routes. Inclusion of the EBOV GP was based on its favorable immune cell targeting and the strong innate responses elicited by the VSV-EBOV vaccine. Our data indicates no difference of ANDV GPC expressing VSV vectors in pre-exposure immunization independent of route, but a potential benefit of the bivalent VSVs following peri- and post-exposure intraperitoneal vaccination.

A Numerically Subdominant CD8 T Cell Response to Matrix Protein of Respiratory Syncytial Virus Controls Infection with Limited Immunopathology

CD8 T cells are involved in pathogen clearance and infection-induced pathology in respiratory syncytial virus (RSV) infection. Studying bulk responses masks the contribution of individual CD8 T cell subsets to protective immunity and immunopathology. In particular, the roles of subdominant responses that are potentially beneficial to the host are rarely appreciated when the focus is on magnitude instead of quality of response. Here, by evaluating CD8 T cell responses in CB6F1 hybrid mice, in which multiple epitopes are recognized, we found that a numerically subdominant CD8 T cell response against D^bM₁₈₇ epitope of the virus matrix protein expressed high avidity TCR and enhanced signaling pathways associated with CD8 T cell effector functions. Each D^bM₁₈₇ T effector cell lysed more infected targets on a per cell basis than the numerically dominant K^dM2₈₂ T cells, and controlled virus replication more efficiently with less pulmonary inflammation and illness than the previously well-characterized K^dM2₈₂ T cell response. Our data suggest that the clinical outcome of viral infections is determined by the integrated functional properties of a variety of responding CD8 T cells, and that the highest magnitude response may not necessarily be the best in terms of benefit to the host. Understanding how to induce highly efficient and functional T cells would inform strategies for designing vaccines intended to provide T cell-mediated immunity.

CD8 T cells play a key role in RSV clearance, immunopathology and disease. Therefore, CD8 T cells can help or harm the host depending on their timing, magnitude, and function. The CD8 T cell response represents a heterogeneous population of cells with phenotypically and functionally diverse subsets, and needs to at least be studied at the level of epitope specificity to understand how to diminish the risk of immunopathology. Studying the bulk response masks distinct contributions of individual CD8 T subsets to immunity and immunopathology. Focusing on CD8 T cell response with the highest magnitude overlooks role of subdominant responses. Here, we studied response to different epitopes and revealed that a numerically subdominant CD8 T cell response against D^bM₁₈₇ epitope of the virus matrix protein controlled virus replication efficiently with limited pulmonary inflammation and illness compared to the previously well-characterized and numerically dominant K^dM2₈₂ T cell response. Our data show that selectively boosting of epitope-specific CD8 T cell responses may be more beneficial than indiscriminant boosting of all available epitopes to achieve rapid viral clearance while limiting immunopathology. This work has implications for antigen design of vaccines intended to induce T-cell-mediated immunity.

Stat1-Deficient Mice Are Not an Appropriate Model for Efficacy Testing of Recombinant Vesicular Stomatitis Virus-Based Filovirus Vaccines

Stat1(-/-) mice lack a response to interferon α, β, and γ, allowing for replication of nonadapted wild-type (wt) Ebolavirus and Marburgvirus. We sought to establish a mouse model for efficacy testing of live attenuated recombinant vesicular stomatitis virus (rVSV)-based filovirus vaccine vectors using wt Ebolavirus and Marburgvirus challenge strains. While infection of immunocompetent mice with different rVSV-based filovirus vectors did not cause disease, infection of Stat1(-/-) mice with the same vectors resulted in systemic infection and lethal outcome for the majority of tested rVSVs. Despite differences in viral loads, organ tropism was remarkably similar between rVSV filovirus vaccine vectors and rVSVwt, with the exception of the brain. In conclusion, Stat1(-/-) mice are not an appropriate immunocompromised mouse model for efficacy testing of live attenuated, replication-competent rVSV vaccine vectors.

Pilot study of a pain assessment tool in the Neonatal Intensive Care Unit

OBJECTIVES

To develop and validate a pain assessment tool to assess procedural pain experienced by mechanically ventilated neonates.

METHODS

Assessment of ventilated infants, before, during and after a known routine traumatic procedure using the Nepean Neonatal Intensive Care Unit Pain Assessment Tool (NNICUPAT). This tool scores physiological and behavioural responses to pain. Variables used in the NNICUPAT included facial expression, body movement, skin colour, saturation, respiratory rate, heart rate and nurses' perception of pain. To test the validity of the NNICUPAT, it was compared to a visual analogue scale (VAS), which is a unidimesional observation measure, where zero equals no pain and 10 equals severe pain.

RESULTS

Thirty ventilated neonates (mean gestation 28 +/- 3.3 standard deviation (SD)) weeks) were enrolled in the pilot study over a 9-month period. The total score before the procedure was: 0.26 +/- 0.14 (mean +/- standard error of the mean (SEM)) range 0-3; total score during the procedure 5.1 +/- 2.2 (mean +/- SD) range 1-10; and the total score after the procedure was 0.26 +/- 0.15 (mean +/- SEM) range 0-3. There was a significant correlation between the NNICUPAT and the VAS during the procedure (r = 0.825, P = < 0.01) and after the procedure (r = 0.375, P = < 0.05). Inter-rater reliability was calculated between the principle coder and other coders (using the NNICUPAT) and showed a significant correlation before (r = 0.88, P < 0.01) and during (r = 0.88, P < 0.01) the procedure.

CONCLUSIONS

The NNICUPAT does show validity in the assessment of procedural pain in the ventilated neonate. Further evaluation of both inter- and intra-rater reliability will be necessary to establish the ongoing validity of the NNICUPAT.