A Glycosylated RBD Protein Induces Enhanced Neutralizing Antibodies against Omicron and Other Variants with Improved Protection against SARS-CoV-2 Infection.

SARS-CoV-2 has mutated frequently since its first emergence in 2019. Numerous variants, including the currently emerging Omicron variant, have demonstrated high transmissibility or increased disease severity, posing serious threats to global public health. This study describes the identification of an immunodominant non-neutralizing epitope on SARS-CoV-2 receptor-binding domain (RBD). A subunit vaccine against this mutant RBD, constructed by masking this epitope with a glycan probe, did not significantly affect RBD's receptor-binding affinity or antibody-binding affinity, or its ability to induce antibody production. However, this vaccine enhanced the neutralizing activity of this RBD and its protective efficacy in immunized mice. Specifically, this vaccine elicited significantly higher-titer neutralizing antibodies than the prototypic RBD protein against Alpha (B.1.1.7 lineage), Beta (B.1.351 lineage), Gamma (P.1 lineage), and Epsilon (B.1.427 or B.1.429 lineage) variant pseudoviruses containing single or combined mutations in the spike (S) protein, albeit the neutralizing antibody titers against some variants were slightly lower than against original SARS-CoV-2. This vaccine also significantly improved the neutralizing activity of the prototypic RBD against pseudotyped and authentic Delta (B.1.617.2 lineage) and Omicron (B.1.1.529 lineage) variants, although the neutralizing antibody titers were lower than against original SARS-CoV-2. In contrast to the prototypic RBD, the mutant RBD completely protected human ACE2 (hACE2)-transgenic mice from lethal challenge with a prototype SARS-CoV-2 strain and a Delta variant without weight loss. Overall, these findings indicate that this RBD vaccine has broad-spectrum activity against multiple SARS-CoV-2 variants, as well as the potential to be effective and have improved efficacy against Omicron and other pandemic variants. IMPORTANCE Several SARS-CoV-2 variants have shown increased transmissibility, calling for a need to develop effective vaccines with broadly neutralizing activity against multiple variants. This study identified a non-neutralizing epitope on the receptor-binding domain (RBD) of SARS-CoV-2 spike protein, and further shielded it with a glycan probe. A subunit vaccine based on this mutant RBD significantly enhanced the ability of prototypic RBD against multiple SARS-CoV-2 variants, including the Delta and Omicron strains, although the neutralizing antibody titers against some of these variants were lower than those against original SARS-CoV-2. This mutant vaccine also enhanced the protective efficacy of the prototypic RBD vaccine against SARS-CoV-2 infection in immunized animals. In conclusion, this study identified an engineered RBD vaccine against Omicron and other SARS-CoV-2 variants that induced stronger neutralizing antibodies and protection than the original RBD vaccine. It also highlights the need to improve the effectiveness of current COVID-19 vaccines to prevent pandemic SARS-CoV-2 variants.

Male Partner Involvement in the Utilization of Hospital Delivery Services by Pregnant Women Living with HIV in Sub Saharan Africa: A Systematic Review and Meta-analysis.

Objective The level of male partner involvement in hospital delivery by pregnant women living with HIV in sub Saharan Africa (SSA) is low. We conducted a systematic review and meta-analysis to identify the approaches that are used in improving male partner involvement and their impact on the utilization of hospital delivery services by pregnant women living with HIV in SSA. Methods Ovid Medline, Embase, PsycINFO, Cochrane library, ClinicalTrials.gov, Web of Science and Current Controlled Trials were searched. Only studies carried out in SSA that reported an approach used in involving male partners and the impact on the uptake of hospital delivery services irrespective of the language and date of publication were included. Odds ratios were extracted or calculated from studies and combined in a meta-analysis using the statistical package Stata version 11.0. A forest plot was used to show the impact of various male involvement approaches. A funnel plot was used to report publication bias. Results From an initial 2316 non-duplicate articles, 08 articles were included in the systematic review and meta-analysis. The overall pooled OR was 1.56 (95% CI 1.45-1.68). After stratification, the odds ratios were: 1.51 (95% CI 1.38-1.65), 1.58 (95% CI 1.38-1.80), 3.47 (95% CI 2.16-5.58) for complex community interventions without community health workers (CHWs), complex community interventions with community health workers, and verbal encouragement respectively. The overall I-square was 91.0% but after stratification into the three different approaches, the I-squared within the complex community intervention without CHWs group was 0.0%. Conclusions for Practice Complex community interventions and verbal encouragement increase the utilization of hospital delivery services by pregnant women living with HIV in SSA. The overall heterogeneity was high but very low for studies that used complex community interventions without CHWs. More well conducted studies (including randomized controlled trials) are needed in future to add to the quality of evidence.

Male partner involvement in increasing the uptake of infant antiretroviral prophylaxis/treatment in sub Saharan Africa: A systematic review and meta-analysis.

BACKGROUND: Infant antiretroviral prophylaxis plays an important role towards ensuring the reduction of HIV transmission from mother to child in the postpartum period. However in sub Saharan Africa (SSA), the low level of involvement of male partners may hinder the uptake of such services by HIV positive mothers. We conducted a systematic review and meta-analysis to determine the impact of male partner involvement approaches on the uptake of infant antiretroviral prophylaxis in SSA. METHODS: In this systematic review and meta-analysis, Ovid Medline, Embase, PsycINFO, Cochrane library, ClinicalTrials.gov, Web of Science and Current Controlled Trials were searched from 1st December 2015 up until 30th March 2016. Only studies carried out in SSA that reported an approach used in involving male partners and the impact on the uptake of infant antiretroviral prophylaxis irrespective of the Language and date of publication were included. Odds ratios were extracted or calculated from studies and combined in a meta-analysis using the statistical package Stata version 11.0. Forest plots were generated using the random effect model. RESULTS: From an initial 2316 non-duplicate articles, 09 articles were included in the systematic review and meta-analysis. The pooled unadjusted odds ratio was 2.09(95% CI: 1.31 to 3.36) while the unadjusted odds ratios for enhanced psychosocial interventions (02 studies pooled), complex community interventions (02 studies pooled), verbal encouragement (02 studies pooled) and invitation letters(03 pooled studies) were 3.48(95% CI: 1.42 to 8.53), 1.85(95%CI: 0.85 to 4.03), 2.37(95%CI: 1.22 to 4.61) and 1.81(95%CI: 0.64 to 5.14) respectively. I squared was 89.5%, p < 0.001 and the heterogeneity was not explained by any of the variables in meta-regression. CONCLUSION: There was stronger evidence for enhanced psychosocial intervention and verbal encouragement in increasing the uptake of infant prophylaxis. The high heterogeneity suggests more studies are needed to draw a definite inference from the meta-analysis. More studies with larger sample sizes that are conducted using similar methods are needed in the future. TRIAL REGISTRATION: Prospero registration number: 42016032673 .

Characterization of human respiratory syncytial virus in children with severe acute respiratory infection before and during the COVID-19 pandemic.

Objectives: Annual outbreaks of human respiratory syncytial virus (HRSV) are caused by newly introduced and locally persistent strains. During the COVID-19 pandemic, global and local circulation of HRSV significantly decreased. This study was conducted to characterize HRSV in 2018-2022 and to analyze the impact of COVID-19 on the evolution of HRSV. Design/methods: Combined oropharyngeal and nasopharyngeal swabs were collected from children hospitalized with severe acute respiratory infection at two hospitals in Zambia. The second hypervariable region of the attachment gene G was targeted for phylogenetic analysis. Results: Of 3113 specimens, 504 (16.2%) were positive for HRSV, of which 131 (26.0%) and 66 (13.1%) were identified as HRSVA and HRSVB, respectively. In early 2021, an increase in HRSV was detected, caused by multiple distinct clades of HRSVA and HRSVB. Some were newly introduced, whereas others resulted from local persistence. Conclusions: This study provides insights into the evolution of HRSV, driven by global and local circulation. The COVID-19 pandemic had a temporal impact on the evolution pattern of HRSV. Understanding the evolution of HRSV is vital for developing strategies for its control.

Characterization of Rotavirus Strains Responsible for Breakthrough Diarrheal Diseases among Zambian Children Using Whole Genome Sequencing.

The occurrence of rotavirus (RV) infection among vaccinated children in high-burden settings poses a threat to further disease burden reduction. Genetically altered viruses have the potential to evade both natural infection and vaccine-induced immune responses, leading to diarrheal diseases among vaccinated children. Studies characterizing RV strains responsible for breakthrough infections in resource-limited countries where RV-associated diarrheal diseases are endemic are limited. We aimed to characterize RV strains detected in fully vaccinated children residing in Zambia using next-generation sequencing. We conducted whole genome sequencing on Illumina MiSeq. Whole genome assembly was performed using Geneious Prime 2023.1.2. A total of 76 diarrheal stool specimens were screened for RV, and 4/76 (5.2%) were RV-positive. Whole genome analysis revealed RVA/Human-wt/ZMB/CIDRZ-RV2088/2020/G1P[4]-I2-R2-C2-M2-A2-N2-T2-E2-H2 and RVA/Human-wt/ZMB/CIDRZ-RV2106/2020/G12P[4]-I1-R2-C2-M2-A2-N1-T2-E1-H2 strains were mono and multiple reassortant (exchanged genes in bold) respectively, whilst RVA/Human-wt/ZMB/CIDRZ-RV2150/2020/G12P[8]-I1-R1-C1-M1-A1-N1-T1-E1-H1 was a typical Wa-like strain. Comparison of VP7 and VP4 antigenic epitope of breakthrough strains and Rotarix strain revealed several amino acid differences. Variations in amino acids in antigenic epitope suggested they played a role in immune evasion of neutralizing antibodies elicited by vaccination. Findings from this study have the potential to inform national RV vaccination strategies and the design of highly efficacious universal RV vaccines.

SARS-CoV-2 Antibody Effectiveness Is Influenced by Non-Epitope Mutation/Binding-Induced Denaturation of the Epitope 3D Architecture.

The public health threat from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to intensify with emerging variants of concern (VOC) aiming to render COVID-19 vaccines/infection-induced antibodies redundant. The SARS-CoV-2 spike protein is responsible for receptor binding and infection of host cells making it a legitimate antibody target. Antibodies mostly target epitopes in the receptor binding domain (RBD). Mutations occurring within epitopes influence antibody specificity and function by altering their 3D architecture. However, the mechanisms by which non-epitope mutations in the RBD influence antibody specificity and function remain a mystery. We used Protein Data Bank (PDB) deposited 3D structures for the original, Beta, Delta, BA.1, and BA.2 RBD proteins in complex with either neutralizing antibodies or Angiotensin-Converting Enzyme 2 (ACE2) to elucidate the structural and mechanistic basis for neutralizing antibody evasion driven by non-epitope amino acid substitutions in the RBD. Since the mechanism behind the extensively reported functional discrepancies between the same antibody when used individually and when used in an antibody cocktail is lacking, we explored the structural basis for this inconsistency. Finally, since SARS-CoV-2 antibodies are viral mutagens, we deciphered determinants for antibody-pressured amino acid substitutions. On the one hand, we show that non-epitope mutations in the RBD domain of SARS-CoV-2 VOC influence the formation of hydrogen bonds in the paratope-epitope interface by repositioning RBD amino-acid sidechains (AASCs). This increases the distance between complementary donor/acceptor atoms on paratope and epitope AASCs leading to weaker or the complete prevention of the formation of hydrogen bonds in the paratope-epitope interface. On the other hand, we show that SARS-CoV-2 VOC employ the same strategy to simultaneously search for complementary donor/acceptor atoms on ACE2 AASCs to form new interactions, potentially favoring increased viral transmission. Additionally, we illustrate that converting the spike protein to an RBD, a deletion mutation, also repositions epitope AASCs and that AASC interactions in the paratope-epitope interface vary when an antibody is used individually versus when utilized as a cocktail with other antibodies. Finally, we show that the process of substituting immunogenic RBD amino acids begins with the repositioning of their AASCs induced by immune/antibody pressure. We show that donor/acceptor atoms from any amino acid can determine cross-reactivity instead, provided they possess and present spatially pairing donor/acceptor atoms. By studying structural alignments for PDB deposited antibody-RBD 3D structures and relating them to published binding and neutralization profiles of the same antibodies, we demonstrate that minor structural alterations such as epitope AASC repositioning have a major impact on antibody effectiveness and, hence, should receive adequate attention given that protein structure dictates protein function.

Switching Heavy Chain Constant Domains Denatures the Paratope 3D Architecture of Influenza Monoclonal Antibodies.

Several human monoclonal Abs for treating Influenza have been evaluated in clinical trials with limited success despite demonstrating superiority in preclinical animal models including mice. To conduct efficacy studies in mice, human monoclonal Abs are genetically engineered to contain mouse heavy chain constant domain to facilitate the engagement of Fc-receptors on mouse immune effector cells. Although studies have consistently reported discrepancies in Ab effectiveness following genetic engineering, the structural and mechanistic basis for these inconsistencies remain uncharacterized. Here, we use homology modeling to predict variable region (VR) analogous monoclonal Abs possessing human IgG1, mouse IgG1, and mouse IgG2a heavy chain constant domains. We then examine predicted 3D structures for variations in the spatial location and orientation of corresponding paratope amino acid residues. By structurally aligning crystal structures of Fabs in complex with hemagglutinin (HA), we show that corresponding paratope amino acid residues for VR-analogous human IgG1, mouse IgG1, and mouse IgG2a monoclonal Abs interact differentially with HA suggesting that their epitopes might not be identical. To demonstrate that variations in the paratope 3D fine architecture have implications for Ab specificity and effectiveness, we genetically engineered VR-analogous human IgG1, human IgG4, mouse IgG1, and mouse IgG2a monoclonal Abs and explored their specificity and effectiveness in protecting MDCK cells from infection by pandemic H1N1 and H3N2 Influenza viruses. We found that VR-analogous monoclonal Abs placed on mouse heavy chain constant domains were more efficacious at protecting MDCK cells from Influenza virus infection relative to those on human heavy chain constant domains. Interestingly, mouse but not human heavy chain constant domains increased target breadth in some monoclonal Abs. These data suggest that heavy chain constant domain sequences play a role in shaping Ab repertoires that go beyond class or sub-class differences in immune effector recruitment. This represents a facet of Ab biology that can potentially be exploited to improve the scope and utilization of current therapeutic or prophylactic candidates for influenza.

Effective vaccination strategy using SARS-CoV-2 spike cocktail against Omicron and other variants of concern.

The SARS-CoV-2 Omicron variant harbors more than 30 mutations in its spike (S) protein. Circulating Omicron subvariants, particularly BA5 and other variants of concern (VOCs), show increased resistance to COVID-19 vaccines that target the original S protein, calling for an urgent need for effective vaccines to prevent multiple SARS-CoV-2 VOCs. Here, we evaluated the neutralizing activity and protection conferred by a BA1-S subunit vaccine when combined with or used as booster doses after, administration of wild-type S protein (WT-S). A WT-S/BA1-S cocktail, or WT-S prime and BA1-S boost, induced significantly higher neutralizing antibodies against pseudotyped Omicron BA1, BA2, BA2.12.1, and BA5 subvariants, and similar or higher neutralizing antibodies against the original SARS-CoV-2, than the WT-S protein alone. The WT-S/BA1-S cocktail also elicited higher or significantly higher neutralizing antibodies than the WT-S-prime-BA1-S boost, WT-S alone, or BA1-S alone against pseudotyped SARS-CoV-2 Alpha, Beta, Gamma, and Delta VOCs, and SARS-CoV, a closely related beta-coronavirus using the same receptor as SARS-CoV-2 for viral entry. By contrast, WT-S or BA1-S alone failed to induce potent neutralizing antibodies against all these viruses. Similar to the WT-S-prime-BA1-S boost, the WT-S/BA1-S cocktail completely protected mice against the lethal challenge of a Delta variant with negligible weight loss. Thus, we have identified an effective vaccination strategy that elicits potent, broadly, and durable neutralizing antibodies against circulating SARS-CoV-2 Omicron subvariants, other VOCs, original SARS-CoV-2, and SARS-CoV. These results will provide useful guidance for developing efficacious vaccines that inhibit current and future SARS-CoV-2 variants to control the COVID-19 pandemic.

The effectiveness of tenofovir-based pre-exposure prophylaxis for prevention of HIV acquisition among sub-Saharan African women at high risk: a systematic review.

INTRODUCTION: women in sub-Saharan Africa (SSA) are disproportionately affected by the HIV epidemic. In 2019, they constituted 59% of new infections; thus, they remain a key population for control. Public health interventions to prevent acquisition of HIV in this high-risk population are urgently needed. Tenofovir-based pre-exposure prophylaxis (TFV-PrEP) has been shown to reduce HIV infections in other key populations. However, comprehensive evidence regarding TFV-PrEP effectiveness in women living in SSA has not been determined. Therefore, we undertook a systematic review to determine the effectiveness of tenofovir-1% (TFV-1%) vaginal gel, oral tenofovir (TFV) and tenofovir-emtricitabine (TDF-FTC) pre-exposure prophylaxis for primary acquisition of HIV in at-risk women living in SSA. METHODS: OVID Medline, Embase, CENTRAL, Web of Science and Clinical Trials.gov were searched for eligible studies from 1st January 2020 to 31st July 2020. Only randomised controlled trials (RCTs) conducted in women living in SSA were included. Measures of effectiveness (hazard ratios (HR), incidence rate ratios (IRR)) were extracted from individual studies to determine the effectiveness of TFV-PrEP in preventing HIV infection among at-risk women living in SSA. RESULTS: from 2002 non-duplicate articles, four RCTs evaluating the effectiveness of one or more of the interventions against placebos were included. TFV-1% vaginal gel, oral TDF or TDF-FTC were not effective in preventing the acquisition of HIV infection in women living in SSA. However, poor adherence by study participants could have confounded the true effectiveness of TFV-PrEP in this high risk population. Meta-analysis was not conducted given the limited number of eligible studies identified from the search. CONCLUSION: the current evidence does not support the effectiveness of TFV-PrEP for HIV in SSA women. More studies aimed at addressing factors driving low adherence to HIV interventions in this high risk population are urgently needed in order to improve the design of future RCTs leading to the determination of more reliable estimates of TFV-1% vaginal gel or oral TDF or TDF-FTC effectiveness. Protocol registration: this systematic review was not registered in PROSPERO.

Orthohantaviruses, Emerging Zoonotic Pathogens.

Orthohantaviruses give rise to the emerging infections such as of hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS) in Eurasia and the Americas, respectively. In this review we will provide a comprehensive analysis of orthohantaviruses distribution and circulation in Eurasia and address the genetic diversity and evolution of Puumala orthohantavirus (PUUV), which causes HFRS in this region. Current data indicate that the geographical location and migration of the natural hosts can lead to the orthohantaviruses genetic diversity as the rodents adapt to the new environmental conditions. The data shows that a high level of diversity characterizes the genome of orthohantaviruses, and the PUUV genome is the most divergent. The reasons for the high genome diversity are mainly caused by point mutations and reassortment, which occur in the genome segments. However, it still remains unclear whether this diversity is linked to the disease's severity. We anticipate that the information provided in this review will be useful for optimizing and developing preventive strategies of HFRS, an emerging zoonosis with potentially very high mortality rates.

The impact of approaches in improving male partner involvement in the prevention of mother-to-child transmission of HIV on the uptake of safe infant feeding practices by HIV positive women in sub-Saharan Africa. A systematic review and meta-analysis.

BACKGROUND: The low level of male partner involvement in Prevention of Mother to Child Transmission of HIV services such as safe infant feeding practices poses a serious challenge to the implementation of guidelines on safe infant feeding and may undermine efforts towards elimination of mother to child transmission of HIV in sub Saharan Africa(SSA). We conducted a systematic review and meta-analysis to identify the approaches that have been utilized to improve male partner involvement in PMTCT services as well as their impact on the uptake of safe infant feeding practices by HIV positive mothers in SSA. METHODS: In this systematic review and meta-analysis, Ovid Medline, Embase, PsycINFO, Cochrane library, ClinicalTrials.gov, Web of Science and Current Controlled Trials were searched. Only studies performed in SSA that reported an approach that specifically involved male partners and its impact on the uptake of safe infant feeding practices (irrespective of the language and date of publication) were included. Odds ratios were extracted or calculated from studies and combined in a meta-analysis using the statistical package Stata version 11.0. Forest plots were generated using the random effect model. RESULTS: From an initial 2416 non-duplicate articles, 06 articles were included in the systematic review and meta-analysis. The overall pooled unadjusted OR was 3.08[95%CI: 2.58-3.68], while the effect sizes for interventions aimed at promoting male partner involvement such as verbal encouragement, complex community intervention and enhanced psychosocial interventions were 1.93[95%CI: 1.34-2.79], 3.45[95%CI: 2.79-4.25] and 5.14[95%CI: 2.42-10.90] respectively. Using only adjusted odd ratios, the pooled adjusted OR = 1.78[95%CI: 1.35-2.34]. The I2 = 60.1% p = 0.057 using adjusted ORs. CONCLUSION: Interventions aimed at promoting male partner involvement such as enhanced psychosocial interventions, verbal encouragement and complex community interventions increase the uptake of safe infant feeding options. The heterogeneity was moderate among studies. More studies including randomised trials that will recruit larger, representative samples of patients are needed in the future. Prospero registration number: 42016032673.

Clinical Efficacy, Safety, and Immunogenicity of a Live Attenuated Tetravalent Dengue Vaccine (CYD-TDV) in Children: A Systematic Review with Meta-analysis.

BACKGROUND: Dengue hemorrhagic fever is the leading cause of hospitalization and death in children living in Asia and Latin America. There is an urgent need for an effective and safe dengue vaccine to reduce morbidity and mortality in this high-risk population given the lack of dengue specific treatment at present. This review aims to determine the efficacy, safety, and immunogenicity of CYD-TDV vaccine in children. METHODS: This is a systematic review including meta-analysis of randomized controlled clinical trial data from Embase, Medline, the Cochrane Library, Web of Science, and ClinicalTrials.gov. Studies that assessed CYD-TDV vaccine efficacy [(1 - RR)*100], safety (RR), and immunogenicity (weighted mean difference) in children were included in this study. Random effects model was employed to analyze patient-level data extracted from primary studies. RESULTS: The overall efficacy of CYD-TDV vaccine was 54% (40-64), while serotype-specific efficacy was 77% (66-85) for DENV4, 75% (65-82) for DENV3, 50% (36-61) for DENV1, and 34% (14-49) for DENV2. 15% (-174-74) vaccine efficacy was obtained for the unknown serotype. Meta-analysis of included studies with longer follow-up time (25 months) revealed that CYD-TDV vaccine significantly increased the risk of injection site reactions (RR = 1.1: 1.04-1.17; p-value = 0.001). Immunogenicity (expressed as geometric mean titers) in descending order was 439.7 (331.7-547.7), 323 (247 - 398.7), 144.1 (117.9-170.2), and 105 (88.7-122.8) for DENV3, DENV2, DENV1, and DENV4, respectively. CONCLUSION: CYD-TDV vaccine is effective and immunogenic in children overall. Reduced efficacy of CYD-TDV vaccine against DENV2 notoriously known for causing severe dengue infection and dengue outbreaks cause for serious concern. Post hoc meta-analysis of long-term follow-up data (≥25 months) from children previously vaccinated with CYD-TDV vaccine is needed to make a conclusion regarding CYD-TDV vaccine safety in children. However, CYD-TDV vaccine should be considered for use in regions where DENV2 is not endemic as currently there is no specific treatment for dengue infection.