Immunity to Sda1 Protects against Infection by Sda1+ and Sda1− Serotypes of Group A Streptococcus

Group A Streptococcus (GAS) causes a variety of diseases globally. The DNases in GAS promote GAS evasion of neutrophil killing by degrading neutrophil extracellular traps (NETs). Sda1 is a prophage-encoded DNase associated with virulent GAS strains. However, protective immunity against Sda1 has not been determined. In this study, we explored the potential of Sda1 as a vaccine candidate. Sda1 was used as a vaccine to immunize mice intranasally. The effect of anti-Sda1 IgG in neutralizing degradation of NETs was determined and the protective role of Sda1 was investigated with intranasal and systemic challenge models. Antigen-specific antibodies were induced in the sera and pharyngeal mucosal site after Sda1 immunization. The anti-Sda1 IgG efficiently prevented degradation of NETs by supernatant samples from different GAS serotypes with or without Sda1. Sda1 immunization promoted clearance of GAS from the nasopharynx independent of GAS serotypes but did not reduce lethality after systemic GAS challenge. Anti-Sda1 antibody can neutralize degradation of NETs by Sda1 and other phage-encoded DNases and decrease GAS colonization at the nasopharynx across serotypes. These results indicate that Sda1 can be a potential vaccine candidate for reduction in GAS reservoir and GAS tonsillitis-associated diseases.

Nanotechnologies in Delivery of DNA and mRNA Vaccines to the Nasal and Pulmonary Mucosa

Recent advancements in the field of in vitro transcribed mRNA (IVT-mRNA) vaccination have attracted considerable attention to such vaccination as a cutting-edge technique against infectious diseases including COVID-19 caused by SARS-CoV-2. While numerous pathogens infect the host through the respiratory mucosa, conventional parenterally administered vaccines are unable to induce protective immunity at mucosal surfaces. Mucosal immunization enables the induction of both mucosal and systemic immunity, efficiently removing pathogens from the mucosa before an infection occurs. Although respiratory mucosal vaccination is highly appealing, successful nasal or pulmonary delivery of nucleic acid-based vaccines is challenging because of several physical and biological barriers at the airway mucosal site, such as a variety of protective enzymes and mucociliary clearance, which remove exogenously inhaled substances. Hence, advanced nanotechnologies enabling delivery of DNA and IVT-mRNA to the nasal and pulmonary mucosa are urgently needed. Ideal nanocarriers for nucleic acid vaccines should be able to efficiently load and protect genetic payloads, overcome physical and biological barriers at the airway mucosal site, facilitate transfection in targeted epithelial or antigen-presenting cells, and incorporate adjuvants. In this review, we discuss recent developments in nucleic acid delivery systems that target airway mucosa for vaccination purposes.

The right time and place: time- and age-dependent vaccine-enhanced mucosal immunity to parasite infection

Individuals vary broadly in their response to vaccination and subsequent exposure to infection, causing persistence of both infection and transmission. The prevalence of poor vaccine responders hampers the development of vaccines, especially against parasitic helminths. Yet despite having substantial economic and societal impact, the immune mechanisms that underlie such variability, especially at the site of parasite infection, remain poorly understood. Previous trials using a prototype vaccine for the control of the gastric parasitic Teladorsagia circumcincta, one of the highest impact parasites affecting sheep, revealed substantial variation in protection between individuals, which we hypothesised may in part be driven by age at vaccination. Here, to characterise how immunity at the mucosal site of infection developed in vaccinated lambs, we inserted gastric cannulae into the abomasa (true stomachs) of three-month- and six-month-old lambs before vaccination, and performed a longitudinal analysis of their local immune response during subsequent challenge infection. We found that the vaccine caused systemic changes in the baseline immune profile within the abomasum before any parasite exposure had occurred and reduced parasite burden and egg output once lambs were infected, regardless of age. However, age affected how vaccinated lambs responded to subsequent infection across multiple immune pathways, with only a minority of protective immune pathways being independent of age. This resulted in younger lambs being more susceptible to infection regardless of vaccine status. The identification of age-dependent (mostly adaptive) and age-independent (mostly innate) protective immune pathways should help refine the formulation of vaccines against these and potentially other helminth parasites of ruminants, and could indicate specificities of anti-helminth immunity more generally.

Seroconversion and Skin Mucosal Parameters during Koi Herpesvirus Shedding in Common Carp, Cyprinus carpio

Seroconversion and the mucosal lysozyme G (lysG), complement 3 (c3), and immunoglobulins M (IgMsec) and Z2 (IgZ2) were measured for up to 900 degree days (DD) in skin swabs from common carp exposed to koi herpesvirus (KHV or CyHV-3) at either a non-permissive temperature (12 °C) or permissive temperatures (17 and 22 °C), and in survivors subjected to temperature increase to 22 °C 500 DD after the initial exposure. The survival rate at 22 °C varied from 100% in fish initially exposed at 12 °C, to 20% at 17 °C and 0% at 22 °C. Viral shedding episodes lasted for up to 29 days (493 DD) for fish clinically infected at 17 °C, and up to 57 days (684 DD) for asymptomatic fish held at 12 °C. Up-regulation of lysG transcripts was measured at 17 and 22 °C. Down-regulation of c3 and IgMsec transcripts was measured independent of the water temperature, followed by up-regulation after the temperature increase coinciding with seroconversion and clearance of KHV from the skin mucus. IgZ2 mRNA showed a negative correlation with IgM transcripts. KHV subversion of the complement system at the mucosal site coupled with poor immunoglobulin secretion during the viral replication might contribute to the long window of viral shedding, thus facilitating viral transmission.

CLINICAL APPROACH AND MANAGEMENT OF ERYTHEMA MULTIFORME –Case Report

Erythema Multiforme (EM) is a rare, autoimmune mucocutaneous disorder characterized by polymorphous oral presentation and target lesions in the skin. It is a type IV hypersensitivity reaction, triggered by infections, drugs and rarely idiopathic. EM minor shows ulcerations involving a single mucosal site with typical skin target lesions. EM often reduces the quality of life and increases the morbidity due to difficulty in swallowing, speech and mouth opening. This case report highlights the management approach of EM minor in a 32-year-old male patient and its response to systemic steroids using sequential clinical photographs with 1-month follow up. Keywords: Erythema Multiforme; minor; vesiculobullous; corticosteroids; idiopathic

Anatomically remote education of B cells is required for colonic health

Mucosa-associated lymphoid tissues contain roughly 80% of all immune cells and produce virtually all of the body’s IgA1–3. Although the majority of IgA-secreting cells educated within a mucosal site home back to the same anatomic region, some cells are also found in distant mucosal tissues2–6. These observations underlie the notion of a common mucosal immune system, which holds that anatomically unrelated mucosal sites are functionally connected by a shared immune system2,3. However, the ontological basis of this separation between site of immune education and functionality has remained elusive. Here we show that mice lacking Peyer’s patches (PPs)—small-intestinal lymphoid tissue covered by antigen-sampling M cells—have no immunologic defect in the small-intestinal lamina propria. Surprisingly, the primary immunological abnormality in PP-deficient mice was a reduction in colonic B cells, including plasmablasts but not plasma cells. Adoptive transfer experiments conclusively demonstrated that PP-derived cells preferentially give rise to colonic—but not small-intestinal—B cells and plasmablasts. Finally, these PP-derived colonic B cells were critical for restraining colonic inflammation. Thus, PPs bridge the small-intestinal and colonic immune systems and provide a clear example of immune education being required in an anatomic compartment distinct from the effector site. Our findings, which highlight that the majority of fecal IgA is produced by colonic plasmablasts that originate from PPs, will help inform design of mucosal vaccines.

Lactoferrin translocates to the nucleus of bovine rectal epithelial cells in the presence of Escherichia coli O157:H7

Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a foodborne pathogen which causes illness in humans. Ruminants are the main reservoirs and EHEC predominantly colonizes the epithelium of the recto-anal junction of cattle. Immunosuppression by EHEC promotes re-infection of cattle. However, bovine lactoferrin (bLF) apparently can overrule the immunosuppression by inducing EHEC-specific IgA responses at the mucosal site. The IgA responses are significantly correlated with reduced EHEC shedding and the absence of colonization at the rectal mucosa following re-infection. Therefore, to examine the interaction between bLF and bovine rectal epithelial cells, we first developed a method to establish a primary cell culture of epithelial cells of the rectum of cattle. Furthermore, we used LC–MS/MS to demonstrate the presence of secreted lactoferrin in bovine milk and the absence of a “delta” isoform which is known to translocate to the nucleus of cells. Nevertheless, lactoferrin derived from bovine milk was internalized by rectal epithelial cells and translocated to the nuclei. Moreover, nuclear translocation of bLF was significantly enhanced when the epithelial cells were inoculated with EHEC, as demonstrated by confocal fluorescence microscopy and confirmed by Raman microscopy and 3D imaging.

Intranasal Vaccination With Multiple Virulence Factors Promotes Mucosal Clearance of Streptococcus suis Across Serotypes and Protects Against Meningitis in Mice

Background Streptococcus suis is an emerging zoonotic agent. Its natural habitat is the tonsils, which are the main portals of S. suis entry into the bloodstream of pigs. The remarkable variability of the bacteria and complex pathogenic mechanisms make the development of a vaccine a difficult task. Method Five conserved virulence factors involved in critical events of S. suis pathogenesis were combined and used as an intranasal vaccine (V5). The effect of V5 was investigated with intranasal and systemic challenge models. Results V5 induced antibody and T-cell responses at the mucosal site and systemically. The immunity promoted clearance of S. suis from the nasopharynx independent of S. suis serotypes and reduced lethality after systemic challenge with S. suis serotype 2. Moreover, mice that survived sepsis from intravenous infection developed meningitis, whereas none of these mice showed neuropathological symptoms after V5 receipt. Conclusion Intranasal immunization with multiple conserved virulence factors decreases S. suis colonization at the nasopharynx across serotypes and inhibits the dissemination of the bacteria in the host. The protective mucosal immunity effects would potentially reduce the S. suis reservoir and prevent S. suis disease in pigs.