SARS-CoV-2 adaptive immunity in nursing home residents up to eight months after two doses of the Comirnaty® COVID-19 vaccine

There is scant information as to how SARS-CoV-2 antibody and T-cell immune responses elicited by mRNA COVID-19 vaccines evolve in the general population, and in particular in elderly nursing home residents, who are at increased risk of developing severe clinical forms of COVID-19. We read with interest the work by Tré-Hardy and colleagues who reported a significant antibody decrease at around 6 months after full vaccination in healthcare workers, that was more marked in SARS-CoV-2 naïve vaccinees [1]. The authors suggested that in a supply-limited environment, booster dose schemes may be spared for SARS-CoV-2-experienced individuals. The data presented herein extend this observation to elderly nursing home residents. The current prospective cohort study included 680 (478 female; median age, 87 years; range 65–100) of a cohort of 881 nursing home residents initially recruited from a representative sample of Valencian Community nursing homes (n = 13) for assessment of SARS-CoV-2 immune responses at a median of 3 months (3 M) following full-dose Comirnaty® COVID-19 vaccination [2] who were re-examined at a median of 219 days (range, 139–246) after vaccination (7 M). Out of the 680 participants, 238 had been infected by SARS-CoV-2 prior to receiving the first vaccine dose, as recorded in the electronic Valencia Health System Integrated Databases. Two residents contracted the infection (Delta variant, as documented by whole-genome sequencing) between sampling times (3 M and 7 M). The remaining 440 participants were presumably naïve for SARS-CoV-2 at the time of sampling (7 M).Peer reviewe

SARS-CoV-2 adaptive immunity in nursing home residents following a third dose of the Comirnaty® COVID-19 vaccine

A third Comirnaty® vaccine dose increased SARS-CoV-2-receptor binding domain antibody levels (median of 93-fold) and neutralizing antibody titers against Wuhan-Hu-1 (median, 57-fold), Beta (median, 22-fold), Delta, (median, 43-fold) and Omicron (median, 8-fold) variants, particularly in SARS-CoV-2-naïve individuals, but had a negligible impact on S-reactive T-cell immunity in nursing home residents.Peer reviewe

Cumulative incidence of SARS-CoV-2 infection in the general population of the Valencian Community (Spain) after the surge of the Omicron BA.1 variant

Background Studies investigating the cumulative incidence of and immune status against SARS-CoV-2 infection provide valuable information for shaping public health decision-making. Methods The current cross-sectional, population-based study, conducted in April 2022 in the Valencian Community (VC), recruited 935 participants of all ages. Anti-SARS-CoV-2-Receptor Binding Domain-RBD-total antibodies and anti-Nucleocapsid (N)- IgGs were measured by electrochemiluminescence assays. To account for past SARS-CoV-2 infection the VC microbiology registry (RedMiVa) was interrogated. |Quantitation of neutralizing antibodies (NtAb) against the ancestral and Omicron BA.1 and BA.2 (sub)variants by an S-pseudotyped neutralization assay and for enumeration of SARS-CoV-2-S specific-IFNγ-producing CD4+ and CD8+ T cells by Intracellular Cytokine Staining assay was performed in a subset of participants (n=100 and 137, respectively). Findings The weighted cumulative incidence was 51□9% (95% CI, 48□7–55□1), and was inversely related to age. Anti-RBD total antibodies were detected in 906/931 (97□3%) participants, those vaccinated and SARS-CoV-2-experienced (VAC-ex;=442) displaying higher levels (P<0.001) than vaccinated/naïve (VAC-n;(n=472) and non-vaccinated/experienced (UNVAC-ex; n(n=63). Antibody levels correlated inversely with the time elapsed since receipt of last vaccine dose in VAC-n (Rho, -0□52; 95% CI, -0□59 to -0□45; P<0.001) but not in VAC-ex. NtAbs against Omicron BA.1 were detected in 94%, 75% and 50% of VAC-ex, VAC-n and UNVAC-ex groups, respectively, while in 97%, 84% and 40%, against Omicron BA.2. SARS-CoV-2-S-reactive IFN-γ T cells were detected in 73%, 75%, and 64% for VAC-ex, VAC-n, UNVAC-ex, respectively. Interpretation By April 2022 around half of the VC population had been infected with SARS-CoV-2 and due to extensive vaccination display hybrid immunity. The large percentage of participants with detectable functional antibody and T-cell responses against SARS-CoV-2, which may be cross-reactive to some extent, points towards lower expected severity than in previous waves.We also thank Ana Berenguer, General Director of Analysis and Public Policies of the Presidency of the Generalitat. Eliseo Albert (Juan Rodés Contract; JR20/00011) Estela Giménez (Juan Rodés Contract, JR18/00053) and Ignacio Torres (Río Hortega Contract; CM20/00090) hold contracts funded by the Carlos III Health Institute (co-financed by the European Regional Development Fund, ERDF/FEDER). Ron Geller holds a Ramon y Cajal fellowship from the Spanish Ministry of Economics and Competitiveness (RYC-2015-17517).N

Comparative genomics and evolutionary analysis of Lactococcus garvieae isolated from human endocarditis

Lactococcus garvieae is a well-known pathogen of fish, but is rarely involved in infections in humans and other mammals. In humans, the main clinical manifestation of L. garvieae infections is endocarditis usually related to the ingestion of contaminated food, such as undercooked fish and shellfish. This study presents the first complete genomic sequence of a clinical L. garvieae strain isolated from a patient with endocarditis and its comparative analysis with other genomes. This human isolate contains a circular chromosome of 2 099 060 bp and one plasmid of 50 557 bp. In comparison with other fully sequenced L. garvieae strains, the chromosomal DNA of L. garvieae Lg-Granada carries a low proportion of insertion sequence elements and a higher number of putative prophages. Our results show that, in general, L. garvieae is a highly recombinogenic species with an open pangenome in which almost 30 % of its genome has undergone horizontal transfers. Within the genus Lactococcus, L. lactis is the main donor of genetic components to L. garvieae but, taking Lg-Granada as a representative, this bacterium tends to import more genes from Bacilli taxa than from other Lactococcus species.This work was supported by the Spanish Ministry of Science, Innovation, and Universities [RTI2018-098530-B-I00 and BFU2017-89594-R]. C-F.C. was supported by the Spanish Ministry of Science, Innovation, and Universities [BES-2015-074204].Peer reviewe

Horizontal gene transfer in the molecular evolution of mannose PTS transporters.

International audienceThe phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS) represents hitherto the only example of group translocation transport systems. PTS transporters are exclusively found in bacteria and can be grouped on the basis of sequence and structure into six classes. We have analyzed the evolution of mannose-class PTS transporters. These transporters have a limited distribution among bacteria being mostly harbored by species associated to animals. The results obtained indicate that these genes have undergone a complex evolutionary history, including extensive horizontal gene transfer events, duplications, and nonorthologous displacements. The phylogenetic analysis revealed an early diversification to specialize in different transport capabilities, but these events have also occurred relatively recently. In addition, these transporters can be further divided into seven groups and this division correlates with their transport capabilities. Finally, the consideration of the genomic context allowed us to propose putative functional roles for some uncharacterized PTS transporters. The functional role and distribution of mannose-class PTS transporters suggest that their expansion may have played a significant role in the establishment of symbiotic relationships between animals and some bacteria