Somatically hypermutated antibodies isolated from SARS-CoV-2 Delta infected patients cross-neutralize heterologous variants.

SARS-CoV-2 Omicron variants feature highly mutated spike proteins with extraordinary abilities in evading antibodies isolated earlier in the pandemic. Investigation of memory B cells from patients primarily with breakthrough infections with the Delta variant enables isolation of a number of neutralizing antibodies cross-reactive to heterologous variants of concern (VOCs) including Omicron variants (BA.1-BA.4). Structural studies identify altered complementarity determining region (CDR) amino acids and highly unusual heavy chain CDR2 insertions respectively in two representative cross-neutralizing antibodies-YB9-258 and YB13-292. These features are putatively introduced by somatic hypermutation and they are heavily involved in epitope recognition to broaden neutralization breadth. Previously, insertions/deletions were rarely reported for antiviral antibodies except for those induced by HIV-1 chronic infections. These data provide molecular mechanisms for cross-neutralization of heterologous SARS-CoV-2 variants by antibodies isolated from Delta variant infected patients with implications for future vaccination strategy.

Extensive neutralization against SARS-CoV-2 variants elicited by Omicron-specific subunit vaccine as a heterologous booster.

To overcome the increased risk of SARS-CoV-2 reinfection or post-vaccination infection caused by the Omicron variant, Omicron-specific vaccines were considered a potential strategy. We reported the increased magnitude and breadth of antibody response against VOCs elicited by post-vaccination Delta and Omicron infection, compared to WT infection without vaccination. Then, in mouse models, three doses of Omicron-RBD immunization elicited comparable neutralizing antibody (NAb) titers with three doses of WT-RBD immunization, but the neutralizing activity was not cross-active. By contrast, a heterologous Omicron-RBD booster following two doses of WT-RBD immunization increased the NAb titers against Omicron by 9-folds than the homologous WT-RBD booster. Moreover, it retains neutralization against both WT and current VOCs. Results suggest that Omicron-specific subunit booster shows its advantages in the immune protection from both WT and current VOCs and that SARS-CoV-2 vaccines including two or more virus lineages might improve the NAb response.

Extensive neutralization against SARS-CoV-2 variants elicited by Omicron-specific subunit vaccine as a heterologous booster

To overcome the increased risk of SARS-CoV-2 reinfection or post-vaccination infection caused by the Omicron variant, Omicron-specific vaccines were considered a potential strategy. We reported the increased magnitude and breadth of antibody response against VOCs elicited by post-vaccination Delta and Omicron infection, compared to WT infection without vaccination. Then, in mouse models, three doses of Omicron-RBD immunization elicited comparable neutralizing antibody (NAb) titers with three doses of WT-RBD immunization, but the neutralizing activity was not cross-active. By contrast, a heterologous Omicron-RBD booster following two doses of WT-RBD immunization increased the NAb titers against Omicron by 9 folds than the homologous WT-RBD booster. Moreover, it retains neutralization against both WT and current VOCs. Results suggest that Omicron-specific subunit booster shows its advantages in the immune protection from both WT and current VOCs and that SARS-CoV-2 vaccines including two or more virus lineages might improve the NAb response. Graphical

Prevalence, bio-serotype, antibiotic susceptibility and genotype of Yersinia enterocolitica and other Yersinia species isolated from retail and processed meats in Shaanxi Province, China

This study characterized Yersinia enterocolitica and other Yersinia spp. isolated from retail and processed meats sampled in Yangling, Shaanxi Province, China (2018–2019). The detection rate of Yersinia -positive samples was 14.30% (86/600). Yersinia was commonly prevalent in beefs (32.00%), frozen meats (25.00%), packaged meats (21.65%), and meats from supermarkets (17.23%). Y. enterocolitica was identified as the most prevalent species (50.00%, 62/124), followed by Y. frederiksenii (24.19%), Y. intermedia (16.94%), and Y. kristensenii (8.87%). Most Y. enterocolitica isolates were of bio-serotype 1A/nt (67.74%). Sixty-three isolates (50.81%) carried yst B and two isolates (1.61%) carried rfb C. Yersinia isolates were commonly resistant to ampicillin (91.94%), cefazolin (71.77%), amoxicillin/clavulanic acid (56.45%), cefoxitin (28.23%), and trimethoprim/sulfamethoxazole (1.61%). Sixty-six isolates (53.23%) were resistant to three or more antibiotics. Pulse field gel electrophoresis analysis revealed that the genetic homology of Yersinia isolates between pork, beef, and chicken was low, as was that of biotype 1A isolates. The results indicate that Y. enterocolitica and other Yersinia spp. (especially bio-serotype 1A/nt, ampicillin-resistant, and yst B-carrying strains) are prevalent in retail and processed meats in the study area, which provides valuable baseline data for food safety and public health safeguarding. • Yersinia spp. with different characteristics were prevalent in retail meat. • Yersinia enterocolitica was the most commonly detected species. • Yersinia enterocolitica biotype 1A isolates carried gene yst B and resisted multiple antibiotics. • The genetic relationship of Yersinia isolates between pork, beef, and chicken was diverse. [ FROM AUTHOR] Copyright of LWT - Food Science & Technology is the property of Academic Press Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full . (Copyright applies to all s.)

Protective humoral and cellular immune responses to SARS-CoV-2 persist up to 1 year after recovery.

SARS-CoV-2 vaccination has been launched worldwide to build effective population-level immunity to curb the spread of this virus. The effectiveness and duration of protective immunity is a critical factor for public health. Here, we report the kinetics of the SARS-CoV-2 specific immune response in 204 individuals up to 1-year after recovery from COVID-19. RBD-IgG and full-length spike-IgG concentrations and serum neutralizing capacity decreases during the first 6-months, but is maintained stably up to 1-year after hospital discharge. Even individuals who had generated high IgG levels during early convalescent stages had IgG levels that had decreased to a similar level one year later. Notably, the RBD-IgG level positively correlates with serum neutralizing capacity, suggesting the representative role of RBD-IgG in predicting serum protection. Moreover, viral-specific cellular immune protection, including spike and nucleoprotein specific, persisted between 6 months and 12 months. Altogether, our study supports the persistence of viral-specific protective immunity over 1 year.