Efficacy of Parainfluenza Virus 5 (PIV5)-vectored Intranasal COVID-19 Vaccine as a Single Dose Vaccine and as a Booster against SARS-CoV-2 Variants.

Immunization with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines has greatly reduced coronavirus disease 2019 (COVID-19)-related deaths and hospitalizations, but waning immunity and the emergence of variants capable of immune escape indicate the need for novel SARS-CoV-2 vaccines. An intranasal parainfluenza virus 5 (PIV5)-vectored COVID-19 vaccine CVXGA1 has been proven efficacious in animal models and blocks contact transmission of SARS-CoV-2 in ferrets. CVXGA1 vaccine is currently in human clinical trials in the United States. This work investigates the immunogenicity and efficacy of CVXGA1 and other PIV5-vectored vaccines expressing additional antigen SARS-CoV-2 nucleoprotein (N) or SARS-CoV-2 variant spike (S) proteins of beta, delta, gamma, and omicron variants against homologous and heterologous challenges in hamsters. A single intranasal dose of CVXGA1 induces neutralizing antibodies against SARS-CoV-2 WA1 (ancestral), delta variant, and omicron variant and protects against both homologous and heterologous virus challenges. Compared to mRNA COVID-19 vaccine, neutralizing antibody titers induced by CVXGA1 were well-maintained over time. When administered as a boost following two doses of a mRNA COVID-19 vaccine, PIV5-vectored vaccines expressing the S protein from WA1 (CVXGA1), delta, or omicron variants generate higher levels of cross-reactive neutralizing antibodies compared to three doses of a mRNA vaccine. In addition to the S protein, the N protein provides added protection as assessed by the highest body weight gain post-challenge infection. Our data indicates that PIV5-vectored COVID-19 vaccines, such as CVXGA1, can serve as booster vaccines against emerging variants.

The Peptidoglycan-associated lipoprotein Pal contributes to the virulence of Burkholderia mallei and provides protection against lethal aerosol challenge.

BURKHOLDERIA MALLEI: is a highly pathogenic bacterium that causes the fatal zoonosis glanders. The organism specifies multiple membrane proteins, which represent prime targets for the development of countermeasures given their location at the host-pathogen interface. We investigated one of these proteins, Pal, and discovered that it is involved in the ability of B. mallei to resist complement-mediated killing and replicate inside host cells in vitro, is expressed in vivo and induces antibodies during the course of infection, and contributes to virulence in a mouse model of aerosol infection. A mutant in the pal gene of the B. mallei wild-type strain ATCC 23344 was found to be especially attenuated, as BALB/c mice challenged with the equivalent of 5,350 LD50 completely cleared infection. Based on these findings, we tested the hypothesis that a vaccine containing the Pal protein elicits protective immunity against aerosol challenge. To achieve this, the pal gene was cloned in the vaccine vector Parainfluenza Virus 5 (PIV5) and mice immunized with the virus were infected with a lethal dose of B. mallei. These experiments revealed that a single dose of PIV5 expressing Pal provided 80% survival over a period of 40 days post-challenge. In contrast, only 10% of mice vaccinated with a PIV5 control virus construct survived infection. Taken together, our data establish that the Peptidoglycan-associated lipoprotein Pal is a critical virulence determinant of B. mallei and effective target for developing a glanders vaccine.

Parainfluenza virus 5 (PIV5) amplifying virus-like particles expressing respiratory syncytial virus (RSV) antigens protect mice against RSV infection.

Respiratory syncytial virus (RSV) is the leading cause of bronchiolitis and pneumonia in children under one year of age. In addition to causing severe respiratory diseases in children, it is also a major cause of morbidity and mortality among the elderly and immunocompromised individuals. RSV is the most common cause of lower respiratory tract infections, yet there are currently no licensed vaccines. A parainfluenza virus 5 (PIV5)-based amplifying virus-like particle (AVLP), which enables the use of PIV5 RNA transcription/replication machinery to express gene of interest, has recently been developed. We evaluated the PIV5-based AVLP system as a vaccine platform for RSV by incorporating the fusion protein (F) gene and the transcription factor protein (M2-1) gene of RSV into the PIV5-AVLP backbone (AVLP-F and AVLP-M2-1, respectively). Mice immunized with a single dose of the AVLP-F or AVLP-M2-1 developed RSV-F or RSV-M2-1-specific immune responses, respectively. Both vaccine candidates elicited antigen-specific cell-mediated responses at levels comparable to or higher than an RSV infection. Most importantly, each vaccine was able to induce protection against RSV A2 challenge in the mouse model. These results indicate the potential of the PIV5-based AVLP system as a platform for vaccines against RSV infection.

The autotransporter protein BatA is a protective antigen against lethal aerosol infection with Burkholderia mallei and Burkholderia pseudomallei.

BACKGROUND: Burkholderia mallei and Burkholderia pseudomallei are the causative agents of glanders and melioidosis, respectively. There is no vaccine to protect against these highly-pathogenic and intrinsically antibiotic-resistant bacteria, and there is concern regarding their use as biological warfare agents. For these reasons, B. mallei and B. pseudomallei are classified as Tier 1 organisms by the U.S. Federal Select Agent Program and the availability of effective countermeasures represents a critical unmet need. METHODS: Vaccines (subunit and vectored) containing the surface-exposed passenger domain of the conserved Burkholderia autotransporter protein BatA were administered to BALB/c mice and the vaccinated animals were challenged with lethal doses of wild-type B. mallei and B. pseudomallei strains via the aerosol route. Mice were monitored for signs of illness for a period of up to 40 days post-challenge and tissues from surviving animals were analyzed for bacterial burden at study end-points. RESULTS: A single dose of recombinant Parainfluenza Virus 5 (PIV5) expressing BatA provided 74% and 60% survival in mice infected with B. mallei and B. pseudomallei, respectively. Vaccination with PIV5-BatA also resulted in complete bacterial clearance from the lungs and spleen of 78% and 44% of animals surviving lethal challenge with B. pseudomallei, respectively. In contrast, all control animals vaccinated with a PIV5 construct expressing an irrelevant antigen and infected with B. pseudomallei were colonized in those tissues. CONCLUSION: Our study indicates that the autotransporter BatA is a valuable target for developing countermeasures against B. mallei and B. pseudomallei and demonstrates the utility of the PIV5 viral vaccine delivery platform to elicit cross-protective immunity against the organisms.

Penetración de tres adhesivos en lesionesinterproximales de caries de mancha blanca: estudio in vitro / Penetration of three adhesives in proximal white-spot carious lesions: an in vitro study

Introducción: el tratamiento de lesiones interproximales de caries temprana representa un reto en la concepción moderna de la cariología y la operatoria. Como respuesta, además del diagnóstico temprano, emergen nuevos materiales para controlar laprogresión de la caries temprana. El objetivo de este estudio fue evaluar in vitro el grado de penetración de tres adhesivos: Excite (Ivoclar-Vivadent), Prime & Bond NT (Dentsply) y Single Bond (3M-ESPE), en el sellado de lesiones interproximales no cavitacionales de mancha blanca.Métodos: 117 premolares humanos extraídos con lesión interproximal de mancha blanca I CDAS-II 2 montados enyeso, simulando la situación en cavidad oral, fueron asignados aleatoriamente a uno de los tres grupos; se sellaron las lesiones con cadamaterial previamente mezclado con azul de metileno; se obtuvieron secciones longitudinales de 250 μm y se analizaron en fotografíasobtenidas bajo estereomicroscopía. Se valoró cubrimiento total de la lesión, profundidad histológica de la lesión en zonas y en micrómetros y, penetración máxima del adhesivo. Resultados: se analizaron 116 dientes. Se encontró cubrimiento total de la lesión en52,5%; 75% se ubicaron en la mitad interna del esmalte, con profundidad promedio de 854 ± 493 μm. La máxima penetración promedio del adhesivoen la lesión fue de 697 ± 412 μm. No hubo diferencias estadísticamente significativas entre grupos para las variables (Kruskal Wallis y correlación de Spearman; p > 0,05). Conclusión:estos tres adhesivos de baja viscosidad, con alto contenido de TEGDMA y HEMA,lograron el cubrimiento y la penetración de material para el sellado de lesiones tempranas de caries interproximal.

Introduction: the treatment of early proximal carious lesions represents a challenge to modern conceptions of cariology and operative dentistry. The possible solutions include, besides an early diagnosis, development of new materials to control early cariesprogression. The objective of this in vitro study was to evaluate the degree of penetration of three adhesives: Excite (Ivoclar-Vivadent), Prime & Bond NT (Dentsply), and Single Bond (3M-ESPE), in the process of sealing white-spot non-cavitated proximal lesions. Methods: 117 extracted human premolars with ICDAS 2 white-spot non-cavitated proximal lesions mounted on plaster, to simulate oral cavityconditions, were randomly sorted out in each of the three groups. The lesions were sealed with each of the materials previously mixed with methylene blue; longitudinal sections of 250 μm were obtained, and they were later analyzed on photographs taken with a stereomicroscope. These variables were evaluated: total lesion coating, lesion’s histologic depth (in micrometers), and the adhesive’s maximum penetration.Results: a total of 116 teeth were analyzed. Entire lesion coating was found in 52.5% of the cases; 75% were located in the enamel’s internal half, with an average depth of 854 ± 493 μm. The adhesive’s maximum average lesion penetration was 697 ± 412 μm. No statistical significant differences were found among the groups (Kruskal Wallis and Spearman correlation; p > 0.05). Conclusion: these three low-viscosity adhesives with high amounts of TEGDMA and HEMA effectively achieved covering and penetrating of the material for sealing early proximal carious lesions.