Vaccine development for mosquito-borne viral diseases.

Mosquito-borne viral diseases are a group of viral illnesses that are predominantly transmitted by mosquitoes, including viruses from the Togaviridae and Flaviviridae families. In recent years, outbreaks caused by Dengue and Zika viruses from the Flaviviridae family, and Chikungunya virus from the Togaviridae family, have raised significant concerns for public health. However, there are currently no safe and effective vaccines available for these viruses, except for CYD-TDV, which has been licensed for Dengue virus. Efforts to control the transmission of COVID-19, such as home quarantine and travel restrictions, have somewhat limited the spread of mosquito-borne viral diseases. Several vaccine platforms, including inactivated vaccines, viral-vector vaccines, live attenuated vaccines, protein vaccines, and nucleic acid vaccines, are being developed to combat these viruses. This review analyzes the various vaccine platforms against Dengue, Zika, and Chikungunya viruses and provides valuable insights for responding to potential outbreaks.

SARS-CoV-2 omicron BA.1.1 is highly resistant to antibody neutralization of convalescent serum from the origin strain.

The emergence and rapid spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant (BA.1.1) has attracted global attention. The numerous mutations in the spike protein suggest that it may have altered susceptibility to immune protection elicited by the existing coronavirus disease 2019 (COVID-19) infection. We used a live virus neutralization test and SARS-CoV-2 pseudotype vesicular stomatitis virus vector-based neutralization assay to assess the degree of immune escape efficiency of the original, Delta (B1.617.2), and Omicron strains against the serum antibodies from 64 unvaccinated patients who had recovered from COVID-19 and the results were strongly correlated. The convalescent serum neutralization was more markedly reduced against the Omicron variant (9.4-57.9-fold) than the Delta variant (2.0-4.5-fold) as compared with the original strain. Our results demonstrate the reduced fusion and notable immune evasion capabilities of the Omicron variants, highlighting the importance of accelerating the development of vaccines targeting them.

Adenovirus Vaccine Containing Truncated SARS-CoV-2 Spike Protein S1 Subunit Leads to a Specific Immune Response in Mice.

The development of an efficient and safe coronavirus disease 2019 (COVID-19) vaccine is a crucial approach for managing the severe acute respiratory disease coronavirus 2 (SARS-CoV-2) pandemic in light of current conditions. In this study, we produced a shortened segment of the optimized SARS-CoV-2 spike gene (2043 bp, termed S1) that was able to encode a truncated S1 protein. The protein was tested to determine if it could elicit efficient immunization in mice against SARS-CoV-2. The presence of the S1 protein was confirmed with immunofluorescence and Western blotting. An adenovirus vaccine bearing the S1 gene fragment (Ad-S1) was administered intramuscularly to mice four times over 4 weeks. SARS-CoV-2 S1 protein humoral immunity was demonstrated in all immunized mice. The serum from immunized mice demonstrated excellent anti-infection activity in vitro. A robust humoral immune response against SARS-CoV-2 was observed in the mice after vaccination with Ad-S1, suggesting that the adenovirus vaccine may aid the development of vaccines against SARS-CoV-2 and other genetically distinct viruses.

An updated review of SARS-CoV-2 detection methods in the context of a novel coronavirus pandemic.

The World Health Organization has reported approximately 430 million confirmed cases of coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), worldwide, including nearly 6 million deaths, since its initial appearance in China in 2019. While the number of diagnosed cases continues to increase, the need for technologies that can accurately and rapidly detect SARS-CoV-2 virus infection at early phases continues to grow, and the Federal Drug Administration (FDA) has licensed emergency use authorizations (EUAs) for virtually hundreds of diagnostic tests based on nucleic acid molecules and antigen-antibody serology assays. Among them, the quantitative real-time reverse transcription PCR (qRT-PCR) assay is considered the gold standard for early phase virus detection. Unfortunately, qRT-PCR still suffers from disadvantages such as the complex test process and the occurrence of false negatives; therefore, new nucleic acid detection devices and serological testing technologies are being developed. However, because of the emergence of strongly infectious mutants of the new coronavirus, such as Alpha (B.1.1.7), Delta (B.1.617.2), and Omicron (B.1.1.529), the need for the specific detection of mutant strains is also increasing. Therefore, this article reviews nucleic acid- and antigen-antibody-based serological assays, and compares the performance of some of the most recent FDA-approved and literature-reported assays and associated kits for the specific testing of new coronavirus variants.

Neutralizing Antibodies against the SARS-CoV-2 Delta and Omicron BA.1 following Homologous CoronaVac Booster Vaccination.

Emerging severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants have reduced susceptibility to neutralization by vaccines. In response to the constantly updated variants, a global vaccine booster vaccination program has been launched. In this study, we detected neutralizing antibody levels against wild-type (WT), Delta (B1.617.2), and Omicron BA.1 viruses in serum after each dose of CoronaVac vaccination. We found that booster vaccination significantly increased the levels of neutralizing antibodies against WT, Delta, and Omicron BA.1. Compared with only one vaccination, neutralizing antibody levels increased by 19.2-21.6-fold after a booster vaccination, whilst two vaccinations only produced a 1.5-3.4-fold increase. Our results support the conclusion that the CoronaVac vaccine booster can increase neutralizing antibody levels and cross-reactivity and enhance the body's ability to effectively resist the infection of new coronavirus variants, emphasizing the need for booster vaccination.

Disinfection effect of hexadecyl pyridinium chloride on SARS-CoV-2 in vitro.

The novel coronavirus (COVID-19 or 2019-nCoV) is a respiratory virus that can exist in the mouth and saliva of patients and spreads through aerosol dispersion. Therefore, stomatological hospitals and departments have become high-infection-risk environments. Accordingly, oral disinfectants that can effectively inactivate the virus have become a highly active area of research. Hexadecyl pyridinium chloride, povidone-iodine, and other common oral disinfectants are the natural primary choices for stomatological hospitals. Therefore, this study investigated the inhibitory effect of hexadecyl pyridinium chloride on SARS-CoV-2 in vitro. Vero cells infected with SARS-CoV-2 were used to determine the disinfection effect; the CCK-8 method was used to determine cytotoxicity, and viral load was determined by real-time PCR. The results showed that hexadecyl pyridinium chloride has no obvious cytotoxic effect on Vero cells in the concentration range 0.0125-0.05 mg/mL. The in vitro experiments showed that hexadecyl pyridinium chloride significantly inhibits the virus at concentrations of 0.1 mg/mL or above at 2 min of action. Thus, the results provide experimental support for the use of hexadecyl pyridinium chloride in stomatological hospitals.

Kinetics of severe acute respiratory syndrome coronavirus 2 infection antibody responses

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread rapidly throughout the world, causing severe morbidity and mortality. Since the first reports of Coronavirus disease 2019 (COVID-19) in late 2019, research on the characteristics of specific humoral immunity against SARS-CoV-2 in patients with COVID-19 has made great progress. However, our knowledge of persistent humoral immunity to SARS-CoV-2 infection is limited. The existence of protective immunity after infection will affect future transmission and disease severity. Therefore, it is important to gather knowledge about the kinetics of antibody responses. In this review, we summarize the information obtained so far on the characteristics and kinetics of the SARS-CoV-2 infection of specific humoral immune response, especially in neutralizing antibodies and their relationship with disease severity. In addition, with the emergence of variants of concern, we summarize the neutralizing effect of specific humoral immunity on variants of concern after the initial SARS-CoV-2 infection and vaccination.

Application of bioreactor technology for cell culture-based viral vaccine production: Present status and future prospects

Bioreactors are widely used in cell culture-based viral vaccine production, especially during the coronavirus disease 2019 (COVID-19) pandemic. In this context, the development and application of bioreactors can provide more efficient and cost-effective vaccine production to meet the global vaccine demand. The production of viral vaccines is inseparable from the development of upstream biological processes. In particular, exploration at the laboratory-scale is urgently required for further development. Therefore, it is necessary to evaluate the existing upstream biological processes, to enable the selection of pilot-scale conditions for academic and industrial scientists to maximize the yield and quality of vaccine development and production. Reviewing methods for optimizing the upstream process of virus vaccine production, this review discusses the bioreactor concepts, significant parameters and operational strategies related to large-scale amplification of virus. On this basis, a comprehensive analysis and evaluation of the various process optimization methods for the production of various viruses (SARS-CoV-2, Influenza virus, Tropical virus, Enterovirus, Rabies virus) in bioreactors is presented. Meanwhile, the types of viral vaccines are briefly introduced, and the established animal cell lines for vaccine production are described. In addition, it is emphasized that the co-development of bioreactor and computational biology is urgently needed to meet the challenges posed by the differences in upstream production scales between the laboratory and industry.

Analysis of the Protective Efficacy of Approved COVID-19 Vaccines Against Various Mutants.

The outbreak of COVID-19 (caused by SARS-CoV-2) has posed a significant threat to global public health security because of its high pathogenicity and infectivity. To date, the pathogenic mechanism of this novel coronavirus (SARS-CoV-2) is still unclear, and there is no effective treatment. As one of the most effective strategies to prevent viral infection, vaccines have become a research hotspot. Based on the current understanding of SARS-CoV-2, the research and development of its vaccines cover almost all forms of current vaccine research, including inactivated vaccines, recombinant protein vaccines, viral vector vaccines, and nucleic acid vaccines. Moreover, with the spread of the new mutant virus, it is necessary to evaluate the protection rate of previous administered vaccines. This article reviews the candidate targets, vaccine types, research and development status, progress of SARS-CoV-2 vaccines, and the effectiveness of neutralizing antibodies against SARS-CoV-2 mutants (B.1.1.7, B.1.351, P.1, B.1.617.2, and B.1.1.529) induced by these vaccines, to provide a reference for follow-up research and prevention.

Progress on SARS-CoV-2 3CLpro Inhibitors: Inspiration from SARS-CoV 3CLpro Peptidomimetics and Small-Molecule Anti-Inflammatory Compounds.

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) currently poses a threat to human health. 3C-like proteinase (3CLpro) plays an important role in the viral life cycle. Hence, it is considered an attractive antiviral target protein. Whole-genome sequencing showed that the sequence homology between SARS-CoV-2 3CLpro and SARS-CoV 3CLpro is 96.08%, with high similarity in the substrate-binding region. Thus, assessing peptidomimetic inhibitors of SARS-CoV 3CLpro could accelerate the development of peptidomimetic inhibitors for SARS-CoV-2 3CLpro. Accordingly, we herein discuss progress on SARS-CoV-2 3CLpro peptidomimetic inhibitors. Inflammation plays a major role in the pathophysiological process of COVID-19. Small-molecule compounds targeting 3CLpro with both antiviral and anti-inflammatory effects are also briefly discussed in this paper.

Virucidal effect of povidone-iodine against SARS-CoV-2 in vitro.

OBJECTIVE: To evaluate the antiviral activity of the oral disinfectant povidone-iodine (PVP-I) against severe acute respiratory syndrome-coronavirus-2 (SARS-CoV2) in vitro. METHODS: The cytotoxic effects of PVP-I were determined in Vero and Calu-3 cell lines using that by Cell Counting Kit-8 assay. Viral load in the cell culture medium above infected cells was quantitated using real-time polymerase chain reaction. The cytopathic effect (CPE) and viral infective rate were observed by immunofluorescence microscopy. RESULTS: PVP-I at a concentration >0.5 mg/ml in contact with SARS-CoV-2 for 30 s, 1 min, 2 min and 5 min showed up to 99% viral inhibition. For in vitro testing, upon exposure for 1 min, PVP-I showed a virucidal effect. PVP-I had no cytotoxic effects at the range of concentrations tested (0.125-1 mg/ml; CC50 > 2.75 mM) in Vero and Calu-3 cells. CONCLUSION: These results demonstrate that the ideal contact time was 1 min and the optimal concentration was 1 mg/ml, which provides an experimental basis for the use of oral disinfectants in dental hospitals.

Rational development of a human antibody cocktail that deploys multiple functions to confer Pan-SARS-CoVs protection.

Structural principles underlying the composition and synergistic mechanisms of protective monoclonal antibody cocktails are poorly defined. Here, we exploited antibody cooperativity to develop a therapeutic antibody cocktail against SARS-CoV-2. On the basis of our previously identified humanized cross-neutralizing antibody H014, we systematically analyzed a fully human naive antibody library and rationally identified a potent neutralizing antibody partner, P17, which confers effective protection in animal model. Cryo-EM studies dissected the nature of the P17 epitope, which is SARS-CoV-2 specific and distinctly different from that of H014. High-resolution structure of the SARS-CoV-2 spike in complex with H014 and P17, together with functional investigations revealed that in a two-antibody cocktail, synergistic neutralization was achieved by S1 shielding and conformational locking, thereby blocking receptor attachment and viral membrane fusion, conferring high potency as well as robustness against viral mutation escape. Furthermore, cluster analysis identified a hypothetical 3rd antibody partner for further reinforcing the cocktail as pan-SARS-CoVs therapeutics.

Dynamic Characteristic Analysis of Antibodies in Patients With COVID-19: A 13-Month Study.

There is a worldwide pandemic of Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection; yet our understanding remains limited on the characteristic of antibodies, especially for dynamic long-term tracking. Sequential serum samples were collected up to 416 days post onset of symptoms (POS) from 102 patients who were hospitalized with coronavirus disease 2019 (COVID-19). Immunoglobulin (Ig)G, IgM, and IgA levels targeting SARS-CoV-2 spike 1 receptor-binding domain (S1-RBD), spike 2 extracellular domain (S2-ECD), and nucleocapsid protein (N) were quantified as well as neutralizing activity. We were pleasantly surprised to find that the antibody remained detective and effective for more than a year POS. We also found the varied reactions of different antibodies as time passed: N-IgA rose most rapidly in the early stage of infection, while S2-IgG was present at a high level in the long time of observation. This study described the long traceable antibody response of the COVID-19 and offered hints about targets to screen for postinfectious immunity and for vaccination development of SARS-CoV-2.

Comparison and Analysis of Neutralizing Antibody Levels in Serum after Inoculating with SARS-CoV-2, MERS-CoV, or SARS-CoV Vaccines in Humans.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), Middle East respiratory syndrome coronavirus (MERS-CoV), and severe acute respiratory syndrome coronavirus (SARS-CoV) pose a great threat to humanity. Every pandemic involving these coronaviruses has seriously affected human health and economic development. Currently, there are no approved therapeutic drugs against their infections. Therefore, the development of vaccines is particularly important to combat these coronaviruses. In this review, we summarized and analyzed the progress of vaccines against SARS-CoV, MERS-CoV, and SARS-CoV-2, including inactivated vaccines, live attenuated vaccines, subunit vaccines, nucleic acid vaccines, and viral vector vaccines. In addition, we compared the levels of neutralizing antibodies in the serum of patients with these three kinds of coronaviruses at different stages, and their ability and effects against SARS-CoV-2, MERS-CoV, and SARS-CoV. This review provides useful information for vaccine evaluation and analysis.

Patient-derived SARS-CoV-2 mutations impact viral replication dynamics and infectivity in vitro and with clinical implications in vivo.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread globally with more than 33 million patients diagnosed, taking more than a million lives. Abundant mutations were observed but the functional consequences of these mutations are largely unknown. We report the mutation spectrum, replication dynamics, and infectivity of 11 patient-derived viral isolates in diverse cell lines, including the human lung cancer cell line Calu-3. We observed 46 mutations, including 9 different mutations in the spike gene. Importantly, these viral isolates show significant and consistent variations in replication dynamics and infectivity in tested cell lines, up to a 1500-fold difference in viral titers at 24 h after infecting Calu-3 cells. Moreover, we show that the variations in viral titers among viral isolates are positively correlated with blood clotting function but inversely correlated with the amount of red blood cell and hemoglobin in patients. Therefore, we provide direct evidence that naturally occurring mutations in SARS-CoV-2 can substantially change its replication dynamics and infectivity in diverse human cell lines, with clinical implications in vivo.