Recurrent SARS-CoV-2 spike mutations confer growth advantages to select JN.1 sublineages.

The recently dominant SARS-CoV-2 Omicron JN.1 has evolved into multiple sublineages, with recurrent spike mutations R346T, F456L, and T572I, some of which exhibit growth advantages, such as KP.2 and KP.3. We investigated these mutations in JN.1, examining their individual and combined effects on immune evasion, ACE2 receptor affinity, and in vitro infectivity. F456L increased resistance to neutralization by human sera, including those after JN.1 breakthrough infections, and by RBD class-1 monoclonal antibodies, significantly altering JN.1 antigenicity. R346T enhanced ACE2-binding affinity and modestly boosted the infectivity of JN.1 pseudovirus, without a discernible effect on serum neutralization, while T572I slightly bolstered evasion of SD1-directed mAbs against JN.1's ancestor, BA.2, possibly by altering SD1 conformation. Importantly, expanding sublineages such as KP.2 containing R346T, F456L, and V1104L, showed similar neutralization resistance as JN.1 with R346T and F456L, suggesting V1104L does not appreciably affect antibody evasion. Furthermore, the hallmark mutation Q493E in KP.3 significantly reduced ACE2-binding affinity and viral infectivity, without noticeably impacting serum neutralization. Our findings illustrate how certain JN.1 mutations confer growth advantages in the population and could inform the design of the next COVID-19 vaccine booster.

Detection of equine herpesvirus antibodies in large-scale donkey farms in Liaocheng area.

BACKGROUND: Equine herpesvirus (EHV) can cause respiratory, reproductive and neurological diseases in equine animals, including donkeys. The main pathogens responsible for these diseases are EHV type 1 (EHV-1) and EHV-4. In this study, we collected serum samples from 230 donkeys on 27 large-scale donkey farms to detect EHV-1 and EHV-4 antibodies. We analyzed the presence of EHV antibodies based on region, age and season. RESULTS: Out of the 27 farms, 62.96% (17/27) tested positive for EHV. Of the 230 donkeys tested, 2.61% (6/230) were positive only for EHV-1, 5.22% (12/230) were positive only for EHV-4, and 4.78% (11/230) were positive for both EHV-1 and EHV-4. The highest percentage of positive donkeys (21.28%) was found in Dong'e County. The seropositivity rate among donkeys aged 1-4 years was significantly higher compared to the group of donkeys aged 0-1 year (p < 0.05). Additionally, the positive rate was significantly higher in fall and winter compared to spring and summer (p < 0.05). CONCLUSIONS: Altogether, our findings indicate that large-scale donkey farms in the Liaocheng area have a high prevalence of EHV antibodies. Since Liaocheng is an important donkey trading market in Shandong Province, it is crucial to consider the risk of disease transmission based on our test results. This will help in early detection and prevention of EHV outbreaks.

Human Milk Oligosaccharides in Combination with Galacto- and Long-Chain Fructo-Oligosaccharides Enhance Vaccination Efficacy in a Murine Influenza Vaccination Model.

Early-life nutrition significantly impacts vaccination efficacy in infants, whose immune response to vaccines is weaker compared to adults. This study investigated vaccination efficacy in female C57Bl/6JOlaHsd mice (6 weeks old) fed diets with 0.7% galacto-oligosaccharides (GOS)/long-chain fructo-oligosaccharides (lcFOS) (9:1), 0.3% human milk oligosaccharides (HMOS), or a combination (GFH) for 14 days prior to and during vaccination. Delayed-type hypersensitivity (DTH) was measured by assessing ear swelling following an intradermal challenge. Influvac-specific IgG1 and IgG2a levels were assessed using ELISAs, while splenic T and B lymphocytes were analyzed for frequency and activation via flow cytometry. Additionally, cytokine production was evaluated using murine splenocytes co-cultured with influenza-loaded dendritic cells. Mice on the GFH diet showed a significantly enhanced DTH response (p < 0.05), increased serological IgG1 levels, and a significant rise in memory B lymphocytes (CD27+ B220+ CD19+). GFH-fed mice also exhibited more activated splenic Th1 cells (CD69+ CXCR3+ CD4+) and higher IFN-γ production after ex vivo restimulation (p < 0.05). These findings suggest that GOS/lcFOS and HMOS, particularly in combination, enhance vaccine responses by improving memory B cells, IgG production, and Th1 cell activation, supporting the potential use of these prebiotics in infant formula for better early-life immune development.

Broad-spectrum coronavirus neutralization induced by hetero RBD-Fc protein vaccine.

In the landscape of infectious diseases, human coronaviruses such as SARS-CoV, MERS-CoV, and SARS-CoV-2 pose significant threats, characterized by severe respiratory illnesses and notable resistance to conventional treatments due to their rapid evolution and the emergence of diverse variants, particularly within SARS-CoV-2. This study investigated the development of broad-spectrum coronavirus vaccines using heterodimeric RBD-Fc proteins engineered through the "Knob-into-Hole" technique. We constructed various recombinant proteins incorporating the receptor-binding domains (RBDs) of different coronaviruses. Heterodimers combining RBDs from SARS-CoV-2 with those of SARS-CoV or MERS-CoV elicited superior neutralizing responses compared to homodimeric proteins in murine models. Additionally, heterotetrameric proteins, specifically D614G_Delta/BA.1_XBB.1.5-RBD and MERS_D614G/BA.1_XBB.1.5-RBD, elicited remarkable breadth and potency in neutralizing all known SARS-CoV-2 variants, SARS-CoV, related sarbecoviruses like GD-Pangolin and WIV1, and even MERS-CoV pseudoviruses. Furthermore, these heterotetrameric proteins also demonstrated enhanced cellular immune responses. These findings underscore the potential of recombinant hetero proteins as a universal vaccine strategy against current and future coronavirus threats.

Post-Hoc Analysis of Potential Correlates of Protection of a Recombinant SARS-CoV-2 Spike Protein Extracellular Domain Vaccine Formulated with Advax-CpG55.2-Adjuvant.

SpikoGen® vaccine is a subunit COVID-19 vaccine composed of an insect cell expressed recombinant spike protein extracellular domain formulated with Advax-CpG55.2™ adjuvant. A randomized double-blind, placebo-controlled Phase II clinical trial was conducted in 400 adult subjects who were randomized 3:1 to receive two intramuscular doses three weeks apart of either SpikoGen® vaccine 25 µg or saline placebo, as previously reported. This study reports a post hoc analysis of the trial data to explore potential immune correlates of SpikoGen® vaccine protection. A range of humoral markers collected pre- and post-vaccination, including spike- and RBD-binding IgG and IgA, surrogate (sVNT), and conventional (cVNT) virus neutralization tests were compared between participants who remained infection-free or got infected over three months of follow-up. From 2 weeks after the second vaccine dose, 21 participants were diagnosed with SARS-CoV-2 infection, 13 (4.2%) in the SpikoGen® group and 8 (9%) in the placebo group. Those in the vaccinated group who experienced breakthrough infections had significantly lower sVNT titers (GMT 5.75 µg/mL, 95% CI; 3.72-8.91) two weeks after the second dose (day 35) than those who did not get infected (GMT 21.06 µg/mL, 95% CI; 16.57-26.76). Conversely, those who did not develop SARS-CoV-2 infection during follow-up had significantly higher baseline sVNT, cVNT, spike-binding IgG and IgA, and RBD-binding IgG, consistent with a past SARS-CoV-2 infection. SpikoGen® further reduced the risk of re-infection (OR 0.29) in baseline seropositive (previously infected) as well as baseline seronegative participants. This indicates that while SpikoGen vaccine is protective in seronegative individuals, those with hybrid immunity have the most robust protection.

Immunogenicity and real-world effectiveness of COVID-19 vaccines in Lebanon: Insights from primary and booster schemes, variants, infections, and hospitalization.

In this study, we conducted a case-control investigation to assess the immunogenicity and effectiveness of primary and first booster homologous and heterologous COVID-19 vaccination regimens against infection and hospitalization, targeting variants circulating in Lebanon during 2021-2022. The study population comprised active Lebanese military personnel between February 2021 and September 2022. Vaccine effectiveness (VE) against laboratory-confirmed SARS-CoV-2 infection and associated hospitalization was retrospectively determined during different variant-predominant periods using a case-control study design. Vaccines developed by Sinopharm, Pfizer, and AstraZeneca as well as Sputnik V were analyzed. Prospective assessment of humoral immune response, which was measured based on the SARS-CoV-2 antispike receptor binding domain IgG titer, was performed post vaccination at various time points, focusing on Sinopharm and Pfizer vaccines. Statistical analyses were performed using IBM SPSS and GraphPad Prism. COVID-19 VE remained consistently high before the emergence of the Omicron variant, with lower estimates during the Delta wave than those during the Alpha wave for primary vaccination schemes. However, vaccines continued to offer significant protection against infection. VE estimates consistently decreased for the Omicron variant across post-vaccination timeframes and schemes. VE against hospitalization declined over time and was influenced by the variant. No breakthrough infections progressed to critical or fatal COVID-19. Immunogenicity analysis revealed that the homologous Pfizer regimen elicited a stronger humoral response than Sinopharm, while a heterologous Sinopharm/Pfizer regimen yielded comparable results to the Pfizer regimen. Over time, both Sinopharm's and Pfizer's primary vaccination schemes exhibited decreased humoral immunity titers, with Pfizer being a more effective booster than Sinopharm. This study, focusing on healthy young adults, provides insights into VE during different pandemic waves. Continuous research and monitoring are essential for understanding vaccine-mediated immune responses under evolving circumstances.

Modeling memory B cell responses in a lymphoid organ-chip to evaluate mRNA vaccine boosting.

Predicting the immunogenicity of candidate vaccines in humans remains a challenge. To address this issue, we developed a lymphoid organ-chip (LO chip) model based on a microfluidic chip seeded with human PBMC at high density within a 3D collagen matrix. Perfusion of the SARS-CoV-2 spike protein mimicked a vaccine boost by inducing a massive amplification of spike-specific memory B cells, plasmablast differentiation, and spike-specific antibody secretion. Features of lymphoid tissue, including the formation of activated CD4+ T cell/B cell clusters and the emigration of matured plasmablasts, were recapitulated in the LO chip. Importantly, myeloid cells were competent at capturing and expressing mRNA vectored by lipid nanoparticles, enabling the assessment of responses to mRNA vaccines. Comparison of on-chip responses to Wuhan monovalent and Wuhan/Omicron bivalent mRNA vaccine boosts showed equivalent induction of Omicron neutralizing antibodies, pointing at immune imprinting as reported in vivo. The LO chip thus represents a versatile platform suited to the preclinical evaluation of vaccine-boosting strategies.

Influence of previous COVID-19 exposure and vaccine type (CoronaVac, ChAdOx1 nCov-19 or BNT162b2) on antibody and cytokine (Th1 or Th2) responses.

To achieve global herd immunity, widespread vaccination is the most effective strategy. Vaccines stimulate the immune system, generating cytokines and chemokines, isotype antibodies, and neutralizing antibodies; all these molecules collectively provide a more comprehensive characterization of the immune response post-vaccination. We conducted a longitudinal study in northwestern Mexico, involving 120 individuals before vaccination and after the first dose of the SARS-CoV-2 vaccine, and 46 individuals after their second dose. Our findings reveal that antibody levels stabilize over time; cytokine levels generally increase following the first dose but decrease after the second dose and higher than normal levels in IgG1 and IgG3 concentrations are present. Most of the innate cytokines determined in this study were higher after the first dose of the vaccine. Regardless of previous infection history, this finding suggests that the first dose of the vaccine is crucial and may stimulate immunity by enhancing the innate immune response. Conversely, increased levels of IL-4, indicative of a Th2 response, were found in individuals without prior exposure to the virus and in those vaccinated with CoronaVac. These results suggest that the immune response to COVID-19 vaccines is multi-faceted, with preexisting immunity potentiating a more robust innate response. Vaccine type plays a critical role, with genetic vaccines favoring a Th1 response and inactivated vaccines like CoronaVac skewing toward a Th2 profile.

EpiScan: accurate high-throughput mapping of antibody-specific epitopes using sequence information.

The identification of antibody-specific epitopes on virus proteins is crucial for vaccine development and drug design. Nonetheless, traditional wet-lab approaches for the identification of epitopes are both costly and labor-intensive, underscoring the need for the development of efficient and cost-effective computational tools. Here, EpiScan, an attention-based deep learning framework for predicting antibody-specific epitopes, is presented. EpiScan adopts a multi-input and single-output strategy by designing independent blocks for different parts of antibodies, including variable heavy chain (VH), variable light chain (VL), complementary determining regions (CDRs), and framework regions (FRs). The block predictions are weighted and integrated for the prediction of potential epitopes. Using multiple experimental data samples, we show that EpiScan, which only uses antibody sequence information, can accurately map epitopes on specific antigen structures. The antibody-specific epitopes on the receptor binding domain (RBD) of SARS coronavirus 2 (SARS-CoV-2) were located by EpiScan, and the potentially valuable vaccine epitope was identified. EpiScan can expedite the epitope mapping process for high-throughput antibody sequencing data, supporting vaccine design and drug development. Availability: For the convenience of related wet-experimental researchers, the source code and web server of EpiScan are publicly available at https://github.com/gzBiomedical/EpiScan .

Comparing the immunogenicity of COVID-19 infection and vaccination in pregnant women as measured by anti-S IgG.

BACKGROUND: Pregnancy is a critical time for women, making them more susceptible to infectious diseases like COVID-19. This study aims to determine the immunogenicity of COVID-19 in pregnant women who have been infected compared to those who have received the inactive COVID-19 vaccine. MATERIALS AND METHODS: In this retrospective cohort study, pregnant women who received the inactivated COVID-19 vaccine (Sinopharm) and those with a history of COVID-19 infection during pregnancy were studied. Participants who had experienced stillbirth, received different COVID-19 vaccines, or had intrauterine fetal death were excluded from the study. Overall, the study included 140 participants. The participants were divided into two groups of 70 participants - pregnant women who received the Sinopharm vaccine and pregnant women who had COVID-19 infection during pregnancy. Before delivery, blood samples were collected from all mothers to evaluate the maternal immunoglobulin G (IgG) level. Blood samples were also taken from the baby's umbilical cord during delivery to measure the newborn's IgG level. Additionally, blood samples were collected from babies whose mothers showed signs of acute infection to measure their IgM levels and evaluate vertical transmission. FINDINGS: The study found a significant relationship between the mean level of maternal IgG and umbilical cord IgG within the groups (P < 0.001). The highest levels of maternal IgG (2.50 ± 2.17) and umbilical cord IgG (2.43 ± 2.09) were observed in pregnant women with a previous COVID-19 infection and no history of vaccination (P < 0.001). Only one baby was born with a positive IgM, and this baby was born to a mother who showed signs of COVID-19 infection in the last five days of pregnancy. The mother was 28 years old, with a BMI of 33; it was her first pregnancy, and she gave birth to a male newborn at term. CONCLUSION: Administering an inactivated vaccine during pregnancy can generate immunity in both the mother and the child. However, the vaccine's immunity level may not be as potent as that conferred by COVID-19 infection during pregnancy. Nonetheless, the risk of vertical transmission of COVID-19 is considered minimal and can be classified as negligible.

Immunogenicity and protective efficacy of a recombinant lactococcus lactis vaccine against HSV-1 infection.

BACKGROUND: Herpes simplex virus type 1 (HSV-1) is a major cause of viral encephalitis, genital mucosal infections, and neonatal infections. Lactococcus lactis (L. lactis) has been proven to be an effective vehicle for delivering protein antigens and stimulating both mucosal and systemic immune responses. In this study, we constructed a recombinant L. lactis system expressing the protective antigen glycoprotein D (gD) of HSV-1. RESULTS: To improve the stability and persistence of antigen stimulation of the local mucosa, we inserted the immunologic adjuvant interleukin (IL)-2 and the Fc fragment of IgG into the expression system, and a recombinant L. lactis named NZ3900-gD-IL-2-Fc was constructed. By utilizing this recombinant L. lactis strain to elicit an immune response and evaluate the protective effect in mice, the recombinant L. lactis vaccine induced a significant increase in specific neutralizing antibodies, IgG, IgA, interferon-γ, and IL-4 levels in the serum of mice. Furthermore, in comparison to the mice in the control group, the vaccine also enhanced the proliferation levels of lymphocytes in response to gD. Moreover, recombinant L. lactis expressing gD significantly boosted nonspecific immune reactions in mice through the activation of immune-related genes. Furthermore, following the HSV-1 challenge of the murine lung mucosa, mice inoculated with the experimental vaccine exhibited less lung damage than control mice. CONCLUSION: Our study presents a novel method for constructing a recombinant vaccine using the food-grade, non-pathogenic, and non-commercial bacterium L. lactis. The findings indicate that this recombinant vaccine shows promise in preventing HSV-1 infection in mice.

Immunologic mediators profile in COVID-19 convalescence.

SARS-CoV-2 caused the pandemic situation experienced since the beginning of 2020, and many countries faced the rapid spread and severe form of the disease. Mechanisms of interaction between the virus and the host were observed during acute phase, but few data are available when related to immunity dynamics in convalescents. We conducted a longitudinal study, with 51 healthy donors and 62 COVID-19 convalescent patients, which these had a 2-month follow-up after symptoms recovery. Venous blood sample was obtained from all participants to measure blood count, subpopulations of monocytes, lymphocytes, natural killer cells and dendritic cells. Serum was used to measure cytokines, chemokines, growth factors, anti-N IgG and anti-S IgG/IgM antibodies. Statistic was performed by Kruskal-Wallis test, and linear regression with days post symptoms and antibody titers. All analysis had confidence interval of 95%. Less than 35% of convalescents were anti-S IgM+, while more than 80% were IgG+ in D30. Anti-N IgG decreased along time, with loss of seroreactivity of 13%. Eosinophil count played a distinct role on both antibodies during all study, and the convalescence was orchestrated by higher neutrophil-to-lymphocyte ratio and IL-15, but initial stages were marked by increase in myeloid DCs, B1 lymphocytes, inflammatory and patrolling monocytes, G-CSF and IL-2. Later convalescence seemed to change to cytotoxicity mediated by T lymphocytes, plasmacytoid DCs, VEGF, IL-9 and CXCL10. Anti-S IgG antibodies showed the longest perseverance and may be a better option for diagnosis. The inflammatory pattern is yet present on initial stage of convalescence, but quickly shifts to a reparative dynamic. Meanwhile eosinophils seem to play a role on anti-N levels in convalescence, although may not be the major causative agent. We must highlight the importance of immunological markers on acute clinical outcomes, but their comprehension to potentialize adaptive system must be explored to improve immunizations and further preventive policies.

mRNA-based COVID-19 vaccination of lung transplant recipients with prior SARS-CoV-2 infection induces durable SARS-CoV-2-specific antibodies and T cells.

Lung transplant recipients (LTRs) are particularly at risk of developing severe coronavirus disease-2019 (COVID-19), but are also difficult to protect by vaccination due to their immunocompromised state. Here, we investigated the immunogenicity of mRNA-based COVID-19 vaccines in LTRs who had a prior natural SARS-CoV-2 infection. At a median of 184 days after SARS-CoV-2 infection, LTRs were vaccinated twice with the mRNA-1273 COVID-19 vaccine, with a 28-day interval. Blood samples were obtained pre-vaccination, 28 days after the first dose, and 28 days and 6 months after the second dose. Spike (S-) and nucleocapsid (N-) specific antibodies were measured, as well as neutralization of the ancestral and Omicron BA.5 variant. S-specific T cell responses were evaluated using IFN-γ ELISpot，IGRA, and activation markers by flow cytometry. Phenotyping of T cells was performed by using high-resolution spectral flow cytometry. Most LTRs with prior infection had detectable S-specific antibodies and T cells at baseline. After the first vaccination, S-specific antibody levels increased significantly; an additional increase was observed after the second vaccination. N-specific antibodies decreased during the study period, indicative of the fact that no further breakthrough infections occurred. An increase in IFN-γ producing T cells was observed after the first vaccination, but no additional boost could be detected after the second vaccination. Antibody levels and virus-specific T cell responses remained significantly higher compared to pre-vaccination levels at 6 months post-vaccination, indicating an additive and durable effect of vaccination after infection in LTRs. Neutralizing antibodies were detected against the ancestral strain and retained cross-reactivity with Omicron BA.5, albeit at lower levels. Moreover, the quantity and phenotype of SARS-CoV-2 spike-specific T cells were similar in LTRs compared to controls with hybrid immunity. In conclusion, mRNA-based COVID-19 vaccines are immunogenic in LTRs with prior immunity, and antibody and T cell responses are durable up to 6 months post-vaccination.

Immunogenicity of mRNA vs. BBV152 vaccine boosters against Omicron subvariants: Final results from Phase B of the PRIBIVAC study, a randomized clinical trial.

BACKGROUND: BBV152 (Covaxin™) is a whole-virion inactivated SARS-CoV-2 vaccine mixed with an immune adjuvant. We aimed to compare immune responses after booster vaccination with heterologous BBV152 versus homologous mRNA vaccine. METHODS: We conducted a randomized, participant-blinded, controlled trial. Fifty mRNA-vaccinated participants were enrolled and randomized to receive an mRNA booster (n = 26) or BBV152 (n = 24). Blood samples were collected pre-vaccination, and at Day 7, 28, 180 and 360 post-booster for analysis of humoral and cellular immune responses. Primary end point was the SARS-CoV-2 anti-spike antibody titer at day 28. RESULTS: Recruitment began in January 2022 and was terminated early due to the BBV152 group meeting pre-specified criteria for futility. At Day 28 post-boost, mean SARS-CoV-2 spike antibody titers were lower with BBV152 (2004 IU/mL; 95 % confidence interval [CI], 1132-3548) vs mRNA (26,669 IU/mL; 95 % CI, 21,330-33,266; p < 0.0001), but comparable levels of spike-specific CD4 and cytotoxic T-cells were observed. Anti-spike antibody titers remained significantly different at Day 180: BBV152 4467 IU/mL (95 % CI, 1959-10,186) vs mRNA 20,749 IU/mL (95 % CI, 12,303-35,075; p = 0.0017). Levels of surrogate virus neutralizing antibodies against ancestral and Omicron subvariants BA.1 and BA.2 were significantly higher among mRNA recipients at Day 180, including after adjusting for intercurrent infection. By Day 360, anti-spike antibody titers and neutralizing antibody levels against Omicron subvariants became similar between vaccine groups. By the end of the study, 16 in each arm (mRNA 64 % and BBV152 69.6 %) had breakthrough infections and time to COVID-19 infection between vaccine groups were similar (p = 0.63). CONCLUSIONS: Wild-type SARS-CoV-2 anti-spike antibody titer and surrogate virus neutralizing test levels against wild-type SARS-CoV-2 and Omicron subvariants BA.1/BA.2/BA.5 were significantly higher at Day 28 and 180 in individuals who received booster vaccination with an mRNA vaccine compared with BBV152. CLINICAL TRIAL REGISTRATION NUMBER: NCT05142319.

A recombinant N2 neuraminidase-based CpG 1018® adjuvanted vaccine provides protection against challenge with heterologous influenza viruses in mice and hamsters.

Recombinant influenza virus neuraminidase (NA) is a promising broadly protective influenza vaccine candidate. However, the recombinant protein alone is not sufficient to induce durable and protective immune responses and requires the coadministration of immunostimulatory molecules. Here, we evaluated the immunogenicity and cross-protective potential of a recombinant influenza virus N2 neuraminidase vaccine construct, adjuvanted with a toll-like receptor 9 (TLR9) agonist (CpG 1018® adjuvant), and alum. The combination of CpG 1018 adjuvant and alum induced a balanced and robust humoral and T-cellular immune response against the NA, which provided protection and reduced morbidity against homologous and heterologous viral challenges in mouse and hamster models. This study supports Syrian hamsters as a useful complementary animal model to mice for pre-clinical evaluation of influenza virus vaccines.

Molecular and phenotypic characteristics of respiratory syncytial virus isolates recovered from medically vulnerable children: An exploratory analysis of a phase 2/3 randomized, double-blind, palivizumab-controlled trial of nirsevimab (MEDLEY).

BACKGROUND: Nirsevimab is an extended half-life monoclonal antibody (mAb) licensed for the prevention of respiratory syncytial virus (RSV)-associated lower respiratory tract disease in neonates, infants and medically vulnerable children. We characterized RSV isolates recovered from participants enrolled in MEDLEY: a randomized, palivizumab-controlled phase 2/3 trial of nirsevimab in infants born preterm and/or with congenital heart disease or chronic lung disease of prematurity. METHODS: Participants were assessed in two RSV seasons (Season 1 and 2). Season 1 participants were randomized (2:1) to receive a single dose of nirsevimab (50 mg if weight <5 kg or 100 mg if weight ≥5 kg in Season 1; 200 mg in Season 2) followed by four monthly doses of placebo, or five once-monthly doses of palivizumab (15 mg/kg weight per dose). Season 2 participants continued nirsevimab and placebo (nirsevimab/nirsevimab) or were re-randomized (1:1) to switch to nirsevimab (palivizumab/nirsevimab) or continue palivizumab (palivizumab/palivizumab). Cases of RSV infection were identified by central testing of nasal swabs from participants seeking medical attention for respiratory illnesses. Nirsevimab and palivizumab binding site substitutions were assessed via microneutralization assay. RESULTS: Twenty-five cases of confirmed RSV infection were observed during the trial and sequenced: 12 in nirsevimab recipients and 10 in palivizumab recipients during Season 1, and 1 case in each Season 2 group. Molecular sequencing of RSV A (n = 14) isolates detected no nirsevimab binding site substitutions, and 3 palivizumab neutralization-resistant substitutions (Lys272Met, Lys272Thr, Ser275Leu). The nirsevimab binding site Ile206Met:Gln209Arg and Ile206Met:Gln209Arg:Ser211Asn substitutions were the only anti-RSV mAb binding site substitutions detected among RSV B isolates (n = 11). Nirsevimab neutralized all nirsevimab and palivizumab binding site substitutions in RSV A and B isolates recovered from MEDLEY participants. CONCLUSION: No binding site substitution detected during MEDLEY affected RSV susceptibility to nirsevimab neutralization.

Prevalence of Influenza B/Yamagata Viruses From Season 2012/2013 to 2021/2022 in Italy as an Indication of a Potential Lineage Extinction.

BACKGROUND: Influenza B/Yamagata viruses exhibited weak antigenic selection in recent years, reducing their prevalence over time and requiring no update of the vaccine component since 2015. To date, no B/Yamagata viruses have been isolated or sequenced since March 2020. METHODS: The antibody prevalence against the current B/Yamagata vaccine strain in Italy was investigated: For each influenza season from 2012/2013 to 2021/2022, 100 human serum samples were tested by haemagglutination inhibition (HAI) assay against the vaccine strain B/Phuket/3073/2013. In addition, the sequences of 156 B/Yamagata strains isolated during the influenza surveillance activities were selected for analysis of the haemagglutinin genome segment. RESULTS: About 61.9% of the human samples showed HAI antibodies, and 21.7% had protective antibody levels. The prevalence of antibodies at protective levels in the seasons between the isolation of the strain and its inclusion in the vaccine was between 11% and 25%, with no significant changes observed in subsequent years. A significant increase was observed in the 2020/2021 season, in line with the increase in influenza vaccine uptake during the pandemic. Sequence analysis showed that from 2014/2015 season onward, all B/Yamagata strains circulating in Italy were closely related to the B/Phuket/2013 vaccine strain, showing only limited amino acid variation. CONCLUSIONS: A consistent prevalence of antibodies to the current B/Yamagata vaccine strain in the general population was observed. The prolonged use of a well-matched influenza vaccine and a low antigenic diversity of B/Yamagata viruses may have facilitated a strong reduction in B/Yamagata circulation, potentially contributing to the disappearance of this lineage.

Variant-specific antibody profiling for tracking SARS-CoV-2 variant infections in children and adolescents.

Monitoring the seroprevalence of SARS-CoV-2 in children and adolescents can provide valuable information for effective SARS-CoV-2 surveillance, and thus guide vaccination strategies. In this study, we quantified antibodies against the spike S1 domains of several SARS-CoV-2 variants (wild-type, Alpha, Delta, and Omicron variants) as well as endemic human coronaviruses (HCoVs) in 1,309 children and adolescents screened between December 2020 and March 2023. Their antibody binding profiles were compared with those of 22 pre-pandemic samples from children and adolescents using an in-house Luminex®-based Corona Array (CA). The primary objectives of this study were to (i) monitor SARS-CoV-2-specific antibodies in children and adolescents, (ii) evaluate whether the S1-specific antibody response can identify the infecting variant of concern (VoC), (iii) estimate the prevalence of silent infections, and (iv) test whether vaccination or infection with SARS-CoV-2 induce HCoV cross-reactive antibodies. Both SARS-CoV-2 infection and vaccination induced a robust antibody response against the S1 domain of WT and VoCs in children and adolescents. Antibodies specific for the S1 domain were able to distinguish between SARS-CoV-2 VoCs in infected children. The serologically identified VoC was typically the predominant VoC at the time of infection. Furthermore, our highly sensitive CA identified more silent SARS-CoV-2 infections than a commercial ELISA (12.1% vs. 6.3%, respectively), and provided insights into the infecting VoC. Seroconversion to endemic HCoVs occurred in early childhood, and vaccination or infection with SARS-CoV-2 did not induce HCoV S1 cross-reactive antibodies. In conclusion, the antibody response to the S1 domain of the spike protein of SARS-CoV-2 is highly specific, providing information about the infecting VoC and revealing clinically silent infections.

Enhanced and cross-reactive in vitro memory B cell response against Epstein-Barr virus nuclear antigen 1 in multiple sclerosis.

Multiple sclerosis (MS) is a prototypical autoimmune disease of the central nervous system (CNS). In addition to CD4+ T cells, memory B cells are now recognized as a critical cell type in the disease. This is underlined by the fact that the best-characterized environmental risk factor for MS is the Epstein-Barr virus (EBV), which can infect and persist in memory B cells throughout life. Several studies have identified changes in anti-EBV immunity in patients with MS. Examples include elevated titers of anti-EBV nuclear antigen 1 (EBNA1) antibodies, interactions of these with the MS-associated HLA-DR15 haplotype, and molecular mimicry with MS autoantigens like myelin basic protein (MBP), anoctamin-2 (ANO2), glial cell adhesion molecule (GlialCAM), and alpha-crystallin B (CRYAB). In this study, we employ a simple in vitro assay to examine the memory B cell antibody repertoire in MS patients and healthy controls. We replicate previous serological data from MS patients demonstrating an increased secretion of anti-EBNA1380-641 IgG in cell culture supernatants, as well as a positive correlation of these levels with autoantibodies against GlialCAM262-416 and ANO21-275. For EBNA1380-641 and ANO21-275, we provide additional evidence suggesting antibody cross-reactivity between the two targets. Further, we show that two efficacious MS treatments - natalizumab (NAT) and autologous hematopoietic stem cell transplantation (aHSCT) - are associated with distinct changes in the EBNA1-directed B cell response and that these alterations can be attributed to the unique mechanisms of action of these therapies. Using an in vitro system, our study confirms MS-associated changes in the anti-EBNA1 memory B cell response, EBNA1380-641 antibody cross-reactivity with ANO21-275, and reveals treatment-associated changes in the immunoglobulin repertoire in MS.

Individuals carrying the HLA-B*15 allele exhibit favorable responses to COVID-19 vaccines but are more susceptible to Omicron BA.5.2 and XBB.1.16 infection.

Background: Natural infection or vaccination have provided robust immune defense against SARS-CoV-2 invasion, nevertheless, Omicron variants still successfully cause breakthrough infection, and the underlying mechanisms are poorly understood. Methods: Sequential blood samples were continuously collected at different time points from 252 volunteers who were received the CanSino Ad5-nCoV (n= 183) vaccine or the Sinovac CoronaVac inactivated vaccine (n= 69). The anti-SARS-CoV-2 prototype and Omicron BA.5.2 as well as XBB.1.16 variant neutralizing antibodies (Nab) in sera were detected by ELISA. Sera were also used to measure pseudo and live virus neutralization assay. The associations between the anti-prototype Nab levels and different HLA-ABC alleles were analyzed using artificial intelligence (AI)-deep learning techniques. The frequency of B cells in PBMCs was investigated by flow cytometry assay (FACs). Results: Individuals carrying the HLA-B*15 allele manifested the highest concentrations of anti-SARS-CoV-2 prototype Nab after vax administration. Unfortunately, these volunteers are more susceptible to Omicron BA.5.2 breakthrough infection due to their sera have poorer anti-BA.5.2 Nab and lower levels of viral neutralization efficacy. FACs confirmed that a significant decrease in CD19+CD27+RBD+ memory B cells in these HLA-B*15 population compared to other cohorts. Importantly, generating lower concentrations of cross-reactive anti-XBB.1.16 Nab post-BA.5.2 infection caused HLA-B*15 individuals to be further infected by XBB.1.16 variant. Conclusions: Individuals carrying the HLA-B*15 allele respond better to COVID-19 vax including the CanSino Ad5-nCoV and the Sinovac CoronaVac inactivated vaccines, but are more susceptible to Omicron variant infection, thus, a novel vaccine against this population is necessary for COVID-19 pandemic control in the future.