BECC438b TLR4 agonist supports unique immune response profiles from nasal and muscular DTaP pertussis vaccines in murine challenge models.

The protection afforded by acellular pertussis vaccines wanes over time, and there is a need to develop improved vaccine formulations. Options to improve the vaccines involve the utilization of different adjuvants and administration via different routes. While intramuscular (IM) vaccination provides a robust systemic immune response, intranasal (IN) vaccination theoretically induces a localized immune response within the nasal cavity. In the case of a Bordetella pertussis infection, IN vaccination results in an immune response that is similar to natural infection, which provides the longest duration of protection. Current acellular formulations utilize an alum adjuvant, and antibody levels wane over time. To overcome the current limitations with the acellular vaccine, we incorporated a novel TLR4 agonist, BECC438b, into both IM and IN acellular formulations to determine its ability to protect against infection in a murine airway challenge model. Following immunization and challenge, we observed that DTaP + BECC438b reduced bacterial burden within the lung and trachea for both administration routes when compared with mock-vaccinated and challenged (MVC) mice. Interestingly, IN administration of DTaP + BECC438b induced a Th1-polarized immune response, while IM vaccination polarized toward a Th2 immune response. RNA sequencing analysis of the lung demonstrated that DTaP + BECC438b activates biological pathways similar to natural infection. Additionally, IN administration of DTaP + BECC438b activated the expression of genes involved in a multitude of pathways associated with the immune system. Overall, these data suggest that BECC438b adjuvant and the IN vaccination route can impact efficacy and responses of pertussis vaccines in pre-clinical mouse models.

Immunization with an mRNA DTP vaccine protects against pertussis in rats.

Bordetella pertussis is a Gram-negative bacterium that is the causative agent of the respiratory disease known as pertussis. Since the switch to the acellular vaccines of DTaP and Tap, pertussis cases in the US have risen and cyclically fallen. We have observed that mRNA pertussis vaccines are immunogenic and protective in mice. Here, we further evaluated the pertussis toxoid mRNA antigen and refined the formulation based on optimal pertussis toxin neutralization in vivo. We next evaluated the mRNA pertussis vaccine in Sprague-Dawley rats using an aerosol B. pertussis challenge model paired with whole-body plethysmography to monitor coughing and respiratory function. Female Sprague-Dawley rats were primed and boosted with either commercially available vaccines (DTaP or wP-DTP), an mRNA-DTP vaccine, or mock-vaccinated. The mRNA-DTP vaccine was immunogenic in rats and induced antigen-specific IgG antibodies comparable to DTaP. Rats were then aerosol challenged with a streptomycin-resistant emerging clinical isolate D420Sm1. Bacterial burden was assessed at days 1 and 9 post-challenge, and the mRNA vaccine reduced burden equal to both DTaP and wP-DTP. Whole-body plethysmography revealed that mRNA-DTP vaccinated rats were well protected against coughing which was comparable to the non-challenged group. These data suggest that an mRNA-DTP vaccine is immunogenic in rats and provides protection against aerosolized B. pertussis challenge in Sprague-Dawley rats.

Virus-like particles displaying the mature C-terminal domain of filamentous hemagglutinin are immunogenic and protective against Bordetella pertussis respiratory infection in mice.

Bordetella pertussis, the bacterium responsible for whooping cough, remains a significant public health challenge despite the existing licensed pertussis vaccines. Current acellular pertussis vaccines, though having favorable reactogenicity and efficacy profiles, involve complex and costly production processes. In addition, acellular vaccines have functional challenges such as short-lasting duration of immunity and limited antigen coverage. Filamentous hemagglutinin (FHA) is an adhesin of B. pertussis that is included in all multivalent pertussis vaccine formulations. Antibodies to FHA have been shown to prevent bacterial attachment to respiratory epithelial cells, and T cell responses to FHA facilitate cell-mediated immunity. In this study, FHA's mature C-terminal domain (MCD) was evaluated as a novel vaccine antigen. MCD was conjugated to virus-like particles via SpyTag-SpyCatcher technology. Prime-boost vaccine studies were performed in mice to characterize immunogenicity and protection against the intranasal B. pertussis challenge. MCD-SpyVLP was more immunogenic than SpyTag-MCD antigen alone, and in Tohama I strain challenge studies, improved protection against challenge was observed in the lungs at day 3 and in the trachea and nasal wash at day 7 post-challenge. Furthermore, a B. pertussis strain encoding genetically inactivated pertussis toxin was used to evaluate MCD-SpyVLP vaccine immunity. Mice vaccinated with MCD-SpyVLP had significantly lower respiratory bacterial burden at both days 3 and 7 post-challenge compared to mock-vaccinated animals. Overall, these data support the use of SpyTag-SpyCatcher VLPs as a platform for use in vaccine development against B. pertussis and other pathogens.

Multivalent mRNA-DTP vaccines are immunogenic and provide protection from Bordetella pertussis challenge in mice.

Acellular multivalent vaccines for pertussis (DTaP and Tdap) prevent symptomatic disease and infant mortality, but immunity to Bordetella pertussis infection wanes significantly over time resulting in cyclic epidemics of pertussis. The messenger RNA (mRNA) vaccine platform provides an opportunity to address complex bacterial infections with an adaptable approach providing Th1-biased responses. In this study, immunogenicity and challenge models were used to evaluate the mRNA platform with multivalent vaccine formulations targeting both B. pertussis antigens and diphtheria and tetanus toxoids. Immunization with mRNA formulations were immunogenetic, induced antigen specific antibodies, as well as Th1 T cell responses. Upon challenge with either historical or contemporary B. pertussis strains, 6 and 10 valent mRNA DTP vaccine provided protection equal to that of 1/20th human doses of either DTaP or whole cell pertussis vaccines. mRNA DTP immunized mice were also protected from pertussis toxin challenge as measured by prevention of lymphocytosis and leukocytosis. Collectively these pre-clinical mouse studies illustrate the potential of the mRNA platform for multivalent bacterial pathogen vaccines.