Seroprevalence of Neutralizing Antibodies against Six Human Adenovirus Types Indicates the Low Level of Herd Immunity in Young Children from Guangzhou, China

Human adenoviruses(HAdVs) commonly cause many diseases such as respiratory diseases, gastroenteritis, cystitis worldwide. HAdV-3,-7,-4 and emergent HAdV-55 and HAdV-14 are the most important types causing severe respiratory diseases. There is no effective drug available for clinical treatment, and no vaccine available for the general population.Therefore, it is important to investigate the seroprevalence against HAdV for developing novel vaccines and vectors. In this study, we investigated the seroprevalence and titer levels of neutralizing antibodies(NAb) against HAdV-3,-4,-7,-14,-55,and-11 in total 278 healthy populations between 0 months and 49 years of age(228 children and 50 adults) from Guangzhou. In children under the age of 18 years, the seropositive rates were significantly increased against HAdV-3 at12.07%, 33.96%, and 64.29% and against HAdV-7 at 0%, 18.87%, and 19.05% in age groups of 1–2, 3–5, and 6–17 years,respectively. The seroprevalence was very low(0% - 8.1%) for all other four types. In adults aged between 18 and49 years, HAdV-3,-4, and-7(> 50.00%) were the most common types, followed by HAdV-14(38.00%),-55(34.00%),and-11(24.00%). Adults tended to have high NAb titers against HAdV-4 and-55. HAdV-55-seropositive donors tended to be HAdV-11-and HAdV-14-seropositive. These results indicated the low level of herd immunity against all six HAdV types in young children, and HAdV-14,-55,-11 in adults from Guangzhou City. Our findings demonstrate the importance of monitoring HAdV types and developing vaccines against HAdV for children and adults.

Metagenomic Analysis Reveals A Possible Association Between Respiratory Infection and Periodontitis

Periodontitis is an inflammatory disease that is characterized by progressive destruction of the periodontium and causes tooth loss in adults.Periodontitis is known to be associated with dysbiosis of the oral microflora,which is often linked to various diseases.However,the complexity of plaque microbial communities of periodontitis,antibiotic resistance,and enhanced virulence make this disease difficult to treat.In this study,using metagenomic shotgun sequencing,we investigated the etiology,antibiotic resistance genes(ARGs),and virulence genes(VirGs)of periodontitis.We revealed a significant shift in the composition of oral microbiota as well as several functional pathways that were represented significantly more abundantly in periodontitis patients than in controls.In addition,we observed several positively selected ARGs and VirGs with the Ka/Ks ratio>1 by analyzing our data and a previous periodontitis dataset,indicating that ARGs and VirGs in oral microbiota may be subjected to positive selection.Moreover,5 of 12 positively selected ARGs and VirGs in periodontitis patients were found in the genomes of respiratory tract pathogens.Of note,91.8%of the background VirGs with at least one non-synonymous single-nucleotide polymorphism for natural selection were also from respiratory tract pathogens.These observations suggest a potential association between periodontitis and respiratory infection at the gene level.Our study enriches the knowledge of pathogens and functional pathways as well as the positive selection of antibiotic resistance and pathogen virulence in periodontitis patients,and provides evidence at the gene level for an association between periodontitis and respiratory infection.

A Sensitive and High-Throughput Flow Cytometry-Based Assay for Measuring Antibody Neutralization of Human Adenovirus Type 3

The assessment of neutralization activity is an important step in the evaluation of neutralizing antibodies (NAbs).The traditional methods for measuring the antibody neutralization of human adenovirus type 3 (HAd V-3) are the microneutralization (MN) assay,which has insufficient sensitivity,and the plaque reduction neutralization test (PRNT),which is not suitable for high-throughput screening.Herein,we describe the development of a flow cytometry-based neutralization(FCN) assay for measuring the neutralization of sera,cell culture supernatants,and chimeric antibodies against HAd V-3 on the basis of a recombinant HAd V-3 (r HAd V-3) construct expressing the enhanced green fluorescent protein (EGFP).For flow cytometry-based assays,the optimal cell confluence was determined as 90%,and the virus was titrated using the assay.The established FCN assay follows the percentage law and an optimal MOI of not less than 5 9 10~(-4)was determined by using a purified chimeric antibody.In addition,comparison of the anti-HAd V-3 NAb titers of 72 human serum samples by the MN and FCN assays,showed that both assays correlated strongly with each other.Our FCN assay was an improvement over the MN assay because the observation period was reduced from 3 to 1 days and data analysis could be performed objectively and robotically.Importantly,the newly established FCN assay allows measurement of the neutralization activity of chimeric antibodies expressed in cell culture supernatants.Thus,this sensitive and highthroughput FCN assay is a useful alternative to the MN assay for measuring the antibody neutralization of HAd V-3 and for screening anti-HAd V-3 NAbs in cell culture supernatants.