African swine fever (ASF) is today′s number one threat for the global swine industry. Neither commercial vaccine nor treatment is available against ASF and, thus far, only live attenuated viruses (LAV) have provided robust protection against lethal ASF virus (ASFV) challenge infections. Identification of ASFV proteins inducing protective immune responses is one of the major challenges to develop safer and efficient subunit vaccines. Immunopeptidomic studies recently performed in our laboratory allowed identifying ASFV antigens recognized by ASFV-specific CD8⁺ T-cells. Here, we used data from the SLAI-peptide repertoire presented by a single set of ASFV-infected porcine alveolar macrophages to generate a complex DNA vaccine composed by 15 plasmids encoding the individual peptide-bearing ORFs. DNA vaccine priming improved the protection afforded by a suboptimal dose of the BA71ΔCD2 LAV given as booster vaccination, against Georgia2007/1 lethal challenge. Interestingly, M448R was the only protein promiscuously recognized by the induced ASFV-specific T-cells. Furthermore, priming pigs with DNA plasmids encoding M488R and MGF505-7R, a CD8⁺ T-cell antigen previously described, confirmed these two proteins as T-cell antigens with protective potential. These studies might be useful to pave the road for designing safe and more efficient vaccine formulations in the future.

Fibrinous polyserositis in swine farming is a common pathological finding in nursery animals. The differential diagnosis of this finding should include Glaesserella parasuis (aetiological agent of Glässer’s disease) and Mycoplasma hyorhinis, among others. These microorganisms are early colonizers of the upper respiratory tract of piglets. The composition of the nasal microbiota at weaning was shown to constitute a predisposing factor for the development of Glässer’s disease. Here, we unravel the role of the nasal microbiota in the subsequent systemic infection by M. hyorhinis, and the similarities and differences with Glässer’s disease. Nasal samples from farms with recurrent problems with polyserositis associated with M. hyorhinis (MH) or Glässer’s disease (GD) were included in this study, together with healthy control farms (HC). Nasal swabs were taken from piglets in MH farms at weaning, before the onset of the clinical outbreaks, and were submitted to 16S rRNA gene amplicon sequencing (V3–V4 region). These sequences were analyzed together with sequences from similar samples previously obtained in GD and HC farms. Animals from farms with disease (MH and GD) had a nasal microbiota with lower diversity than those from the HC farms. However, the composition of the nasal microbiota of the piglets from these disease farms was different, suggesting that divergent microbiota imbalances may predispose the animals to the two systemic infections. We also found variants of the pathogens that were associated with the farms with the corresponding disease, highlighting the importance of studying the microbiome at strain-level resolution.

Streptococcus pneumoniae is a nasopharynx colonizer that can invade sterile tissues, causing invasive pneumococcal disease (IPD). Dolosigranulum pigrum and Corynebacterium pseudodiphtheriticum are commensal bacteria commonly isolated from the nasopharynx of healthy children, potentially playing a protective role. This study aims to analyze the effects of D. pigrum and C. pseudodiphtheriticum on S. pneumoniae in vitro growth. Pneumococcal strains were collected from IPD patients and healthy carriers in Catalonia (2016–2023). D. pigrum and C. pseudodiphtheriticum strains were isolated from a healthy child’s nasopharynx. S. pneumoniae was co-cultured with each commensal bacterium in triplicate experiments. Pneumococcal growth was quantified using a real-time PCR assay targeting the lytA gene. The effect of commensal bacteria on pneumococcal growth was evaluated using a linear mixed-effect regression model. Twenty-eight pneumococcal strains expressing 24 different serotypes and 27 clonal types were analyzed (18 isolated in blood and 10 in nasopharyngeal aspirate). Pneumococcal growth was decreased by D. pigrum (β = −0.763, 95% confidence interval [CI]: −0.94 to −0.59, P < 0.0001) and C. pseudodiphtheriticum (β = −0.583, 95% CI: −0.76 to −0.41, P < 0.0001). The combined presence of both had a stronger inhibitory effect (β = −0.971, 95% CI: −1.15 to −0.79, P < 0.0001). No association was found between isolation site or serotype with pneumococcal growth. D. pigrum and C. pseudodiphtheriticum significantly reduced pneumococcal growth, with a synergistic effect when combined. This antagonistic effect supports the potential protective factor of healthy nasopharyngeal microbiota against IPD and the development of these microorganisms as probiotics. IMPORTANCE: Invasive pneumococcal disease (IPD) is a significant worldwide health challenge. The present study highlights the significant inhibitory effect of two commensal bacteria, Dolosigranulum pigrum and Corynebacterium pseudodiphtheriticum , on pneumococcal growth, with a stronger effect observed when both bacteria are present together. Through testing different strains of S. pneumoniae and the implementation of a robust statistical model, this research advances in the knowledge of microbial ecology and provides evidence to support the development of the use of these commensal bacteria as probiotics. These results emphasize the possibility of using the nasopharyngeal microbiota’s natural interactions to mitigate the risk of IPD.

Background: Respiratory tract infections range from asymptomatic colonisation to an invasive disease. Recent studies suggest that nasopharyngeal microbiota may influence this variability. Emerging evidence points to Dolosigranulum pigrum, a nasopharyngeal commensal, as a potentially protective bacterium. This study aimed to identify variables associated with the presence of D. pigrum in the nasopharynx of children with varying respiratory health statuses. Methods: Nasopharyngeal aspirates were collected from children 0.1% of total sequences obtained by 16S rRNA gene sequencing. Variables included sex, breastfeeding, delivery mode, S. pneumoniae carriage, respiratory viruses and clinical features. Results: Among 140 children (73 males, 67 females), D. pigrum was detected in 79 (56.4%): 44/65 in the healthy group; 26/48 of viral and 9/27 IPD cases. Multivariate analysis revealed significant associations with health status and sex. Healthy children were more likely to carry D. pigrum than IPD cases (44/79 vs. 26/79; p= 0.028). Males were more frequently D. pigrum carriers than females (48/79 vs. 31/79; p= 0.033). Conclusion: D. Pigrum was associated with respiratory health, being more prevalent in healthy children, and showed potential sex-related differences.

Background: Serotype 3 (S3) has remained a major cause of invasive pneumococcal disease (IPD) despite its inclusion in 13-valent pneumococcal conjugate vaccine (PCV). In October 2023, a 15-valent PCV (PCV15) including S3 was introduced into the Catalan universal childhood immunization program. Methods: We conducted a retrospective pre-post surveillance study to compare pediatric IPD incidence in Catalonia during a pre-PCV15 period (October 1, 2022-September 30, 2023) and two post-PCV15 periods (October 1, 2023-September 30, 2024, and October 1, 2024-September 30, 2025). All IPD episodes in children <18 years attended in 34 hospitals were included. IPD was defined as detection of S. pneumoniae in a sterile site by culture or PCR. Results: 323 IPD episodes were identified in 319 children (mean age, 4.5 years). Overall IPD incidence declined from 13.0 to 9.4 episodes per 100,000 children in the first post-PCV15 period compared with the pre-PCV15 period (28% reduction; p =0.02), but returned to baseline in the second post-PCV15 period. S3-IPD incidence decreased significantly from 4.1 to 1.6 episodes per 100,000 (60% reduction; p =0.001) in the first post-PCV15 period and remained lower in the second period: 2.3 episodes per 100,000 (42% reduction compared with baseline; p =0.04). In contrast, IPD incidence caused by PCV7 serotypes increased from 0.3 in the pre-PCV15 and first post-PCV15 period to 2.7 episodes per 100,000 in the second post-PCV15 period (690% increase; p <0.001). Conclusion: PCV15 introduction was associated with a sustained reduction in S3-IPD over two years. However, a marked increase in PCV7 serotypes offset overall gains in IPD incidence. SUMMARY: PCV15 introduction in Catalonia achieved sustained reduction in serotype 3 invasive pneumococcal disease over two years, but a marked increase in PCV7 serotypes offset the overall disease reduction in the second post-vaccination year.

The COVID-19 pandemic altered societal habits due to social restrictions and health measures implemented during the first half of 2020. This study aimed to evaluate the association between oral microbiota composition and age, household cohabitation, SARS-CoV-2 infection, and COVID-19 severity among children and adults under home confinement in Barcelona, Spain. A prospective study was conducted between April and June 2020 in the Barcelona Metropolitan Area, including children and adults confined during the pandemic. Multiple participants from the same family households were enrolled. Saliva samples were collected from all participants, and oral microbiota composition was characterized using 16S rRNA gene sequencing. A total of 142 adults and 265 children from 121 households were included. All adults had confirmed SARS-CoV-2 infection, and 20 (14.08%) experienced severe COVID-19. Among children, 58/265 (21.89%) tested positive; all were asymptomatic. In children, oral microbiota diversity and composition did not differ by infection status. In adults, severe COVID-19 was associated with lower diversity and distinct composition compared with mild disease. Marked age-related differences were observed in younger children. Cohabiting individuals shared more amplicon sequence variants than non-cohabitants. Age and cohabitation strongly influenced oral microbiota composition. In adults, microbiota varied with COVID-19 severity, whereas no differences were observed among asymptomatic children.