BACKGROUND:Human adenovirus type 55 (hAd55) infection can lead to acute respiratory diseases that often present with severe symptoms. Despite its persistent prevalence in military camps and communities, there are no commercially available vaccines or vaccine candidates undergoing clinical evaluation; therefore, there is an urgent need to address this. In this study, we evaluated the immunogenicity of inactivated hAd55 isolates and investigated the effects of adjuvants and various immunization intervals. METHODS AND RESULTS:To select a vaccine candidate, four hAd55 strains (6-9, 6-15 (AFMRI 41014), 28-48 (AFMRI 41013), and 12-164 (AFMRI 41012)) were isolated from infected patients in military camps. Sequence analysis revealed no variation in the coding regions of structural proteins, including pentons, hexons, and fibers. Immunization with inactivated hAd55 isolates elicited robust hAd55-specific binding and neutralizing antibody responses in mice, with adjuvants, particularly alum hydroxide (AH), enhancing antibody titers. Co-immunization with AH also induced hAd14-specific neutralizing antibody responses but did not induce hAd11-specific neutralizing antibody responses. Notably, booster immunization administered at a four-week interval resulted in superior immune responses compared with shorter immunization intervals. CONCLUSIONS:Prime-boost immunization with the inactivated hAd55 isolate and an AH adjuvant shows promise as a potential approach for preventing hAd55-induced respiratory disease. Further research is needed to evaluate the efficacy and safety of these vaccine candidates in preventing hAd55-associated respiratory illnesses.
Enteroaggregative Escherichia coli (EAEC) is a major enteric pathogen in low-resource settings. The aim for the present study is to reanalyze the effects of subclinical EAEC infection, alone or in combination with other pathogens, on intestinal function, growth, and cognition in children aged 0-6 months through molecular diagnosis. A total of 1,659 non-diarrheal stool samples from the Etiology, Risk Factors and Interactions of Enteric Infections and Malnutrition and the Consequences for Child Health and Development cohort were analyzed using quantitative polymerase chain reaction testing for 29 enteropathogens. Children were grouped by infection status: EAEC alone or with 1, 2, or ≥3 co-pathogens. Enteroaggregative Escherichia coli and a higher pathogen burden were associated with lower socioeconomic status and greater antibiotic use (P <0.001). Enteroaggregative Escherichia coli with ≥3 co-pathogens was linked to elevated neopterin (β = 687.5; CI: 129.7-1,245.3), increased intestinal permeability (β = 0.41; CI: 0.058-0.77), and a lower length-for-age z-score (β = -0.44; CI: -0.76 to -0.12), and EAEC alone reduced cognitive scores at 15 and 24 months of age (β = -2.82 and -5.02, respectively; CI: -5.15 to -0.48 and -9.81 to -0.22, respectively). Subclinical EAEC infection is associated with inflammation, gut dysfunction, growth failure, and cognitive delay.
Orientia tsutsugamushi is an obligate intracellular bacterium responsible for scrub typhus. It exists as a symbiont within trombiculid mites, of which only the larval stage (or “chigger”) is parasitic. While the role of small mammals in maintaining this vector–pathogen cycle is well-documented, the involvement of birds as hosts for chiggers and/or O. tsutsugamushi remains understudied. Here, we screened chigger mites collected from various bird species in a scrub typhus-endemic country (Malaysia) for O. tsutsugamushi infection, together with organ and tissue samples from red junglefowl (Gallus gallus), domestic chickens (Gallus gallus domesticus) and house crows (Corvus splendens). Chiggers were pooled by species per bird host and assayed using a nested polymerase chain reaction (nPCR) targeting the htrA gene, with a subset of pools subjected to Illumina metagenomic sequencing. Leptotrombidium chiangraiensis chiggers from an O. tsutsugamushi-positive colony maintained in Thailand were used to validate the sequencing strategy. Bird tissue samples were also assayed by htrA-targeted nPCR. Illumina sequencing of pools of L. chiangraiensis from an infected colony showed good coverage across almost the entire O. tsutsugamushi genome. However, O. tsutsugamushi was not detected in pooled DNA samples from bird-associated chiggers by nPCR and neither did metagenomic analysis identify O. tsutsugamushi sequences, except in a Blankaartia acuscutellaris pool from a wild slaty-breasted rail (Lewinia striata). Multiple contigs related to Rickettsiales amplified genetic elements of Orientia origin were observed in this sample, but no core genes were assembled that could be used for strain typing. Among galliform birds and house crows, O. tsutsugamushi DNA was detected in one red junglefowl and one domestic chicken sample by nPCR, and phylogenetic analysis clustered these sequences with Karp isolates. Although Orientia infections in birds and associated chiggers appear rare, our findings suggest that these hosts may contribute to pathogen ecology and dispersal, highlighting the need for broader avian surveillance.
Large critical-size bone defects in the oral and craniofacial region are difficult to regenerate. We evaluated the effectiveness of mRNA encoding bone morphogenic protein-2 (BMP-2) in enhancing bone regeneration using a rat calvarial defect model. Two delivery approaches were investigated: (1) in vivo application of BMP-2 mRNA encapsulated in lipid nanoparticles incorporated in a scaffold, and (2) application of ex vivo BMP-2 mRNA-transfected rat bone marrow mesenchymal stem cells (rBMSCs), loaded on a scaffold and implanted into calvarial defects. The direct application of BMP-2 mRNA encapsulated in lipid nanoparticles improved bone regeneration as indicated by micro-computed tomography analysis. The enhancement was even more pronounced with ex vivo transfected rBMSCs. rBMSCs transfected with FGF-2 mRNA did not improve bone regeneration, either alone or combined with BMP-2 mRNA-transfected rBMSCs. Similarly, PDGF-BB mRNA-transfected rBMSCs failed to enhance bone regeneration alone and notably suppressed BMP-2 mRNA-transfected rBMSCs’ effects. Interestingly, BMP-2 mRNA-transfected rat fibroblasts showed comparable bone regeneration to transfected rBMSCs. Osteogenic differentiation was absent in BMP-2 mRNA-transfected rBMSCs, implying that they may primarily serve as a source of translated BMP-2 for bone regeneration rather than undergoing osteogenic differentiation. These findings highlight the translational potential of BMP-2 mRNA for bone regeneration, particularly in oral and craniofacial applications.
Radical cure of Plasmodium vivax malaria must include elimination of quiescent ‘hypnozoite’ forms in the liver; however, the only FDA-approved treatments are contraindicated in many vulnerable populations. To identify new drugs and drug targets for hypnozoites, we screened the Repurposing, Focused Rescue, and Accelerated Medchem (ReFRAME) library and a collection of epigenetic inhibitors against P. vivax liver stages. From both libraries, we identified inhibitors targeting epigenetics pathways as selectively active against P. vivax and P. cynomolgi hypnozoites. These include DNA methyltransferase inhibitors as well as several inhibitors targeting histone post-translational modifications. Immunofluorescence staining of Plasmodium liver forms showed strong nuclear 5-methylcystosine signal, indicating liver stage parasite DNA is methylated. Using bisulfite sequencing, we mapped genomic DNA methylation in sporozoites, revealing DNA methylation signals in most coding genes. We also demonstrated that methylation level in proximal promoter regions as well as in the first exon of the genes may affect, at least partially, gene expression in P. vivax . The importance of selective inhibitors targeting epigenetic features on hypnozoites was validated using MMV019721, an acetyl-CoA synthetase inhibitor that affects histone acetylation and was previously reported as active against P. falciparum blood stages. In summary, our data indicate that several epigenetic mechanisms are likely modulating hypnozoite formation or persistence and provide an avenue for the discovery and development of improved radical cure antimalarials.
