Evidence for human infection with avian influenza A(H9N2) virus via environmental transmission inside live poultry market in Xiamen, China.

H9N2 avian influenza virus (AIV) has become prevalent in the live poultry market (LPM) worldwide, and environmental transmission mode is an important way for AIVs to infect human beings in the LPM. To find evidence of human infection with the influenza A(H9N2) virus via environmental contamination, we evaluated one human isolate and three environmental isolates inside LPMs in Xiamen, China. The phylogeny, transmissibility, and pathogenicity of the four isolates were sorted out systematically. As for the H9N2 virus, which evolved alongside the "Avian-Environment-Human" spreading chain in LPMs from the summer of 2019 to the summer of 2020, its overall efficiency of contact and aerosol transmissibility improved, which might contribute to the increasing probability of human infection. This study indicated that environmental exposure might act as an important source of human infection in LPMs.

Emerging Omicron subvariants evade neutralizing immunity elicited by vaccine or BA.1/BA.2 infection.

The newly emerging severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron BA.2.75 and BA.2.76 subvariants contained 35 and 29 additional mutations in its spike (S) protein compared with the reference SARS-CoV-2 genome, respectively. Here, we measured the evasion degree of the BA.1, BA.2, BA.4, BA.5, BA.2.75, and BA.2.76 subvariants from neutralizing immunity in people previously infected with the Omicron BA.1 and BA.2, determined the effect of vaccination on immune evasion, and compared the titers of neutralizing antibodies in serums between acute infection and convalescence. Results showed that the neutralization effect of serums from patients with different vaccination statuses and BA.1/BA.2 breakthrough infection decreased with the Omicron evolution from BA.1 to BA.2, BA.4, BA.5, BA.2.75, and BA.2.76. This study also indicated that the existing vaccines could no longer provide effective protection, especially for the emerging BA.2.75 and BA.2.76 subvariants. Therefore, vaccines against emerging epidemic strains should be designed specifically. In the future, we can not only focus on the current strains, but also predict and design new vaccines against potential mutant strains. At the same time, we can combine the virus strains' infection characteristics to develop protective measures for virus colonization areas, such as nasal protection spray. Besides, further studies on the Y248N mutation of BA.2.76 subvariant were also necessary to explore its contribution to the enhanced immune evasion ability.

A rapid and sensitive one-pot platform integrating fluorogenic RNA aptamers and CRISPR-Cas13a for visual detection of monkeypox virus.

The recent global upsurge in Monkeypox virus (MPXV) outbreaks underscores the critical need for rapid and precise diagnostic solutions, particularly in resource-constrained settings. The gold standard diagnostic method, qRT-PCR, is hindered by its time-consuming nature, requirement for nucleic acid purification, expensive equipment, and the need for highly trained personnel. Traditional CRISPR/Cas fluorescence assays, relying on trans-cleavage of ssDNA/RNA reporters labeled with costly fluorophores and quenchers, pose challenges that limit their widespread application, especially for point-of-care testing (POCT). In this study, we utilized a cost-effective and stable fluorogenic RNA aptamer (Mango III), specifically binding and illuminating the fluorophore TO3-3 PEG-Biotin Fluorophore (TO3), as a reporter for Cas13a trans-cleavage activity. We propose a comprehensive strategy integrating RNA aptamer, recombinase-aided amplification (RAA), and CRISPR-Cas13a systems for the molecular detection of MPXV target. Leveraging the inherent collateral cleavage properties of the Cas13a system, we established high-sensitivity and specificity assays to distinguish MPXV from other Orthopoxviruses (OPVs). A streamlined one-pot protocol was developed to mitigate aerosol contamination risks. Our aptamer-coupled RAA-Cas13a one-pot detection method achieved a Limit of Detection (LoD) of 4 copies of target MPXV DNA in just 40 min. Validation using clinical MPX specimens confirmed the rapid and reliable application of our RAA-Cas13a-Apt assays without nucleic acid purification procedure, highlighting its potential as a point-of-care testing solution. These results underscore the user-friendliness and effectiveness of our one-pot RAA-Cas13a-Apt diagnostic platform, poised to revolutionize disease detection and management.

Relationship of various COVID-19 antibody titer with individual characteristics and prediction of future epidemic trend in Xiamen City, China.

Background: Reinfection of coronavirus disease 2019 (COVID-19) has raised concerns about how reliable immunity from infection and vaccination is. With mass testing for the virus halted, understanding the current prevalence of COVID-19 is crucial. This study investigated 1,191 public health workers at the Xiamen Center for Disease Control, focusing on changes in antibody titers and their relationship with individual characteristics. Methods: The study began by describing the epidemiological characteristics of the study participants. Multilinear regression (MLR) models were employed to explore the associations between individual attributes and antibody titers. Additionally, group-based trajectory models (GBTMs) were utilized to identify trajectories in antibody titer changes. To predict and simulate future epidemic trends and examine the correlation of antibody decay with epidemics, a high-dimensional transmission dynamics model was constructed. Results: Analysis of epidemiological characteristics revealed significant differences in vaccination status between infected and non-infected groups (χ2=376.706, P<0.05). However, the distribution of antibody titers among the infected and vaccinated populations was not significantly different. The MLR model identified age as a common factor affecting titers of immunoglobulin G (IgG), immunoglobulin M (IgM), and neutralizing antibody (NAb), while other factors showed varying impacts. History of pulmonary disease and hospitalization influenced IgG titer, and factors such as gender, smoking, family history of pulmonary diseases, and hospitalization impacted NAb titers. Age was the sole determinant of IgM titers in this study. GBTM analysis indicated a "gradual decline type" trajectory for IgG (95.65%), while IgM and NAb titers remained stable over the study period. The high-dimensional transmission dynamics model predicted and simulated peak epidemic periods in Xiamen City, which correlated with IgG decay. Age-group-specific simulations revealed a higher incidence and infection rate among individuals aged 30-39 years during both the second and third peaks, followed by those aged 40-49, 50-59, 18-29, and 70-79 years. Conclusions: Our study shows that antibody titer could be influenced by age, previous pulmonary diseases as well as smoking. Furthermore, the decline in IgG titers is consistent with epidemic trends. These findings emphasize the need for further exploration of these factors and the development of optimized self-protection countermeasures against reinfection.

Etiologic characteristics of avian influenza H11 viruses isolated from the live poultry market in southeast coastal region in China.

Since it was first identified in 1956, the H11 subvariant influenza virus has been reported worldwide. However, due to the low pathogenicity of the H11 subvariant and the absence of its widespread transmission among humans, there are only a few reports on the etiology of the H11 subvariant influenza virus. Therefore, in the present study, we isolated a strain of the H11N3 avian influenza virus (AIV) from poultry feces from the live poultry market in the southeast coastal region of China. Considering that the H11 subvariant is known to cause infections in humans and to enrich the knowledge of the H11 subvariant of the avian influenza virus, the genetics, pathogenicity, and transmissibility of the isolate were studied. The phylogenetic analysis indicated that the H11N3 isolate was of Eurasian origin and carried genes closely related to duck H7N2 and H4N6. The receptor binding analysis revealed that the H11N3 isolate only acquired a binding affinity for avian-derived receptors. In the respiratory system of mice, the isolate could directly cause infection without adaptation. In addition, the results from transmission experiments and antibody detection in guinea pigs demonstrated that H11N3 influenza viruses can efficiently transmit through the respiratory tract in mammalian models. Direct infection of the H11N3 influenza virus without adaptation in the mouse models and aerosol transmission between guinea pig models confirms its pandemic potential in mammals, underscoring the importance of monitoring rare influenza virus subtypes in future studies.

Natural history and cycle threshold values analysis of COVID-19 in Xiamen City, China.

Objective: This study elaborated the natural history parameters of Delta variant, explored the differences in detection cycle thresholds (Ct) among cases. Methods: Natural history parameters were calculated based on the different onset time and exposure time of the cases. Intergenerational relationships between generations of cases were calculated. Differences in Ct values of cases by gender, age, and mode of detection were analyzed statistically to assess the detoxification capacity of cases. Results: The median incubation period was 4 days; the detection time for cases decreased from 25 to 7 h as the outbreak continued. The average generation time (GT), time interval between transmission generations (TG) and serial interval (SI) were 3.6 ± 2.6 days, 1.67 ± 2.11 days and 1.7 ± 3.0 days. Among the Ct values, we found little differences in testing across companies, but there were some differences in the gender of detected genes. The Ct values continuous to decreased with age, but increased when the age was greater than 60. Conclusion: This epidemic was started from aggregation of factories. It is more reasonable to use SI to calculate the effective reproduction number and the time-varying reproduction number. And the analysis of Ct values can improve the positive detection rate and improve prevention and control measures.