Changes and correlation of dengue fever epidemic and Aedes albopictus density in Haizhu district, Guangzhou before and after the COVID-19 pandemic

To analyze the population density, seasonal fluctuation of Aedes albopictus in Haizhu District, Guangzhou from 2017 to 2021, so as to provide a scientific basis for the monitoring and prevention and control of mosquito vector density of dengue fever. The data of dengue fever cases and Aedes surveillance data in Haizhu District, Guangzhou from 2017 to 2021 were collected, and the data of 2017-2019 and 2020-2021 were grouped to compare and analyze the characteristics of dengue epidemic and the density fluctuation of Aedes mosquitoes. A total of 517 dengue cases were reported in Haizhu District, Guangzhou from 2017 to 2021, of which only 7 cases were reported from 2020 to 2021, and the peak period of reported cases every year was August to November. Before the COVID-19 pandemic, there was a positive correlation between the number of local cases and the number of imported cases(rs=0.63, P<0.05) and BI(rs=0.73, P<0.05). The peak density of Aedes was from May to October, and the differences of mean BI(X~2=1 143.40,P<0.001), MOI(X~2=188.30,P<0.001), and SSI(X~2=4 499.43,P<0.001)before and after the COVID-19 pandemic were statistically significant. In general, before and after the COVID-19 pandemic, the density of Aedes in high-risk areas was higher than that in low-risk areas. After COVID-19 pandemic, the number of reported cases and the density of Aedes in Haizhu District decreased, but the density of Aedes in the high-risk area was still higher than that in low-risk areas, and a certain risk of outbreak still existed, so the government should continue to take more precise measures to strictly prevent dengue epidemic.

Interfacial water molecules contribute to antibody binding to the receptor-binding domain of SARS-CoV-2 spike protein.

Antibodies that recognize the spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), especially the neutralizing antibodies, carry great hope in the treatment and final elimination of COVID-19. Driven by a synchronized global effort, thousands of antibodies against the spike protein have been identified during the past two years, with the structural information available at atomistic detail for hundreds of these antibodies. We developed an improved molecular mechanics/Poisson-Boltzmann surface area (MM/PBSA) method including explicitly treated interfacial water to calculate the binding free energy between representative antibodies and the receptor binding domain (RBD) domain of SARS-COV-2 spike proteins. We discovered that explicit treatment of water molecules located at the interface between RBD and antibody effectively improves the results for the WT and variants of concern (VOC) systems. Interfacial water molecules, together with surface and internal water molecules, behave drastically from bulk water and exert peculiar impacts on protein dynamics and energy, and thus warrant explicit treatment to complement implicit solvent models. Our results illustrate the importance of including interfacial water molecules to approach efficient and reliable prediction of binding free energy.Communicated by Ramaswamy H. Sarma.

Characteristic analysis of a local clustered outbreak of COVID-19 pneumonia caused by SARS-CoV-2 omicron BA.2

Objective: To analyze the epidemiological characteristics of a local cluster of corona virus disease 2019 (COVID-19) pneumonia caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron BA.2, and thus provide scientific evidence for the formulation of scientific prevention and control measures. Method: Descriptive epidemiological methods were used to analyze the causes, transmission, vaccination effects and prevention measures of 12 local clustered outbreaks in Haizhu district in March and April 2022 by retrospective investigation. Results: A total of 12 infected patients were reported, all of which were confirmed infected with SARS-CoV-2 Omicron BA.2. Clinical manifestations: 10 cases had fever (83.33%), 7 cases had sore throat (58.33%), 7 cases had cough (58.33%), 5 cases had fatigue (41.67%), and 4 cases had headache or dizziness (33.33%), 2 cases had gastrointestinal symptoms (16.67%), and 1 case had muscle soreness (8.33%). The clinical classification is as follows: 10 cases of mild disease (83.33%), 2 cases of common type (16.67%), no severe disease and no death. The earliest infection time was March 27, and the last case was April 15. The peak incidence was concentrated on April 8 and April 10, with a total of 5 cases (41.67%). The shortest incubation period was 2 days and the longest was 14 days, with an average of 6.55 days. The geographical distribution indicated that 7 cases from Yangyang Clothing Company (58.33%), 3 cases from Guangzhou No. 3 Middle School (25.00%), and 2 cases of family clusters (16.67%). The sex ratio of all patients was 1:3. The youngest age was 18 years old and the oldest was 59 years old. The 12 cases were young adults;of which, 9 cases were 21- < 60 years old (accounting for 75.00%), and 3 cases were 18- < 21 years old (25.00%). Occupational distribution;employees were accounting for 58.33%, followed by unemployed accounting for 25.00%, and students accounting for 16.67%. A 1:3+ matched case-control analysis in 58 high-risk close contacts was conducted, and found that infection and vaccination were not statistically correlated (X2 = 0.861, P > 0.05). Similarly, by conducting a 1:1+ matched case-control analysis, we failed to observed a statistically significantly in the effect of sex on infection (X2 = 0.325, P > 0.05). Conclusions: The outbreak was caused by SARS-CoV-2 Omicron BA.2;the source of infection was still unknown, and there was hidden transmission. Therefore, strengthening personal protection and giving full play to the role of medical units and pharmacies as sentinel points and industry monitoring should be necessary for the normalization of COVID-19 pneumonia prevention and control.

Targeted photodynamic neutralization of SARS-CoV-2 mediated by singlet oxygen.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus has been on a rampage for more than two years. Vaccines in combination with neutralizing antibodies (NAbs) against SARS-CoV-2 carry great hope in the treatment and final elimination of coronavirus disease 2019 (COVID-19). However, the relentless emergence of variants of concern (VOC), including the most recent Omicron variants, presses for novel measures to counter these variants that often show immune evasion. Hereby we developed a targeted photodynamic approach to neutralize SARS-CoV-2 by engineering a genetically encoded photosensitizer (SOPP3) to a diverse list of antibodies targeting the wild-type (WT) spike protein, including human antibodies isolated from a 2003 Severe acute respiratory syndrome (SARS) patient, potent monomeric and multimeric nanobodies targeting receptor-binding domain (RBD), and non-neutralizing antibodies (non-NAbs) targeting the more conserved N-terminal domain (NTD). As confirmed by pseudovirus neutralization assay, this targeted photodynamic approach significantly increased the efficacy of these antibodies, especially that of non-NAbs, against not only the WT but also the Delta strain and the heavily immune escape Omicron strain (BA.1). Subsequent measurement of infrared phosphorescence at 1270 nm confirmed the generation of singlet oxygen (1O2) in the photodynamic process. Mass spectroscopy assay uncovered amino acids in the spike protein targeted by 1O2. Impressively, Y145 and H146 form an oxidization "hotspot", which overlaps with the antigenic "supersite" in NTD. Taken together, our study established a targeted photodynamic approach against the SARS-CoV-2 virus and provided mechanistic insights into the photodynamic modification of protein molecules mediated by 1O2.