Volume 06 · Issue 06 · 2024

Pigs are vital genetic mixing vessels for human and avian influenza viruses because their tracheal epitheliums possess both sialic acid α-2,6-Gal and α-2,3-Gal receptors. Cross-species transmission of influenza A viruses from swine to humans occurs occasionally. The first case of human infection with the Eurasian avian-like H1N1 swine influenza virus (EAH1N1 SIVs) genotype G4 was detected in Jiangsu Province, China, in February 2023, and backtracking epidemiological investigations did not reveal a clear source of the infection. The hemagglutination (HA) and neuraminidase (NA) amino acid variant sites, antiviral drug susceptibility, and antigenic variation of the isolated A/Jiangsu/27271/2023 (JS/27271/23) virus were analyzed, and we evaluated the protective effect of sera collected from occupationally exposed populations in 2024 against the virus. Compared with the vaccine strain, the nucleotide sequence similarities of JS/27271/23 HA and NA were 96.5 % and 95.2 %, respectively. JS/27271/23 was sensitive to polymerase inhibitors (favipiravir and baloxavir), and the antigenicity of its HA protein was 8-fold different from that of the vaccine strain. The percentage of occupationally exposed population with antibody titers of ≥ 40 against A/Hunan/42443/2015 (HN/42443/15) and A/Jiangsu/1/2011 (JS/1/11) were 7.25 % and 2.25 %, respectively, and the geometric mean titers (GMT) were 6.24 and 5.34, respectively. Out of 400 serum samples examined, none had antibody titers of ≥ 40 against JS/27271/23. This suggests that low serum levels of antibodies to EAH1N1 SIVs in occupationally exposed populations may not provide adequate protection because of significant differences in amino acid sites and antigenicity between this virus and the current vaccine strain of EAH1N1 SIVs. There is no evidence of human-to-human transmission of EAH1N1 SIVs. Therefore, surveillance for EAH1N1 SIVs and the development of new vaccine strains are required.

The increase in emerging and reemerging infectious diseases has underscored the need for the prompt monitoring of intact infectious viruses and the quick assessment of their infectivity. However, molecular techniques cannot distinguish between intact infectious and noninfectious viruses. Here, two distinct methodologies have been developed for the expeditious and dependable quantification of intact infectious H1N1 virus, and several experiments have been conducted to substantiate their efficacy. One is an integrated cell absorption quantitative polymerase chain reaction (qPCR) method (ICA-qPCR), and the other is a combined propidium monoazide qPCR method (PMA-qPCR). The quantification limit is 100 cell culture infective dose 50 % (CCID₅₀)/mL in ICA-qPCR following a 1.5-hour cell absorption or 126 CCID₅₀/mL after a 15-minute incubation. For PMA-qPCR, the limit was 2,512 CCID₅₀/mL. The number of genome copies quantified by the ICA-qPCR and PMA-qPCR methods was strongly correlated with the infectious titer determined by the CCID₅₀ assay, thereby enabling the estimation of virus infectivity. The ICA-qPCR and PMA-qPCR methods are both suitable for the identification and quantification of intact infectious H1N1 virus in inactivated samples, wastewater, and biological materials. In conclusion, the ICA-qPCR and PMA-qPCR methods have distinct advantages and disadvantages, and can be used to quantify intact infectious viruses rapidly. These methodologies can facilitate the identification of the presence of intact infectious viruses in wastewater or on pathogen-related physical surfaces in high-level biosafety laboratories and medical facilities. Furthermore, these methodologies can also be utilized to detect other highly pathogenic pathogens.

In 2022, a sharp rise in global cases of mpox virus (MPXV) led the World Health Organization (WHO) to declare it a public health emergency of international concern. However, progress in developing drugs targeting MPXV has been slow. Here, we investigate the natural alkaloid narciclasine as a potential inhibitor of poxviruses. Our investigation demonstrates that narciclasine at 40 nmol/L (nM) to 160 nM dosages effectively blocks vaccinia virus (VACV), a representative poxvirus. Specifically, narciclasine disrupts the production of extracellular enveloped virus (EEV), which is crucial for viral spread. Narciclasine’s antiviral impact is probably attributed to its activation of the RhoA signaling pathway. This study highlights narciclasine’s potential as a promising new therapeutic candidate against poxviruses, offering prospects for its development into a potent antiviral agent that is essential for combating emerging poxvirus outbreaks.

Viral infectious clones (ICs) serve as robust platforms for studying viral biology and screening antiviral agents using reverse genetics. However, the molecular profiles and complex limitations of human coronaviruses (HCoVs) pose a challenge to ICs development. In this study, we report a novel platform to develop the ICs for HCoV-OC43-VR1558 using a one-step assembly method in yeast by transformation-associated recombination (TAR) technology. Recombinant HCoV-OC43-VR1558, named as rOC43(1558)-WT, was rapidly generated by TAR. In addition, recombinant HCoV-OC43-VR1558-expressing reporter genes, named as rOC43(1558)-ns2FusionRluc, was also generated based on TAR by inserting the ns2 region of the IC with Renilla luciferase (Rluc). We further characterized their replication through virus titration using 50 % tissue culture infective dose (TCID₅₀) and indirect immunofluorescence assay (IFA), luciferase reporter assay, and western blotting (WB) assay. The genetic stability of the recombinant HCoV-OC43 was assessed through viral genome sequencing following passaging in BHK-21 cells. These reporter viruses were validated as screening tools for inhibitors in vitro by evaluating the antiviral activities of remdesivir and chloroquine. The phenotypes of HCoV-OC43-VR1558 and HCoV-OC43-VR759 were compared in vitro and in vivo. The TAR-based one-step assembly of IC was successfully applied, facilitating the rapid generation of recombinant HCoV-OC43 and providing a useful platform for the investigation of biological mechanisms, development of vaccines and diagnostic tests, and screening inhibitors of HCoVs.

Recently, there has been a continuous stream of reports on emerging tick-borne pathogens affecting humans. Qinghai Province, located in the northweastern region, is one of China’s major pastoral areas, providing a suitable environment for ticks' survival and transmitting tick-borne pathogens. Here, we collected 560 free-living and parasitic ticks from 11 locations in Qinghai Province using the flag-drag method or tweezers, identifying them as belonging to 4 species of ticks. The overall positivity rate for tick-borne pathogens was 51.61 %, comprising Rickettsia (34.64 %), Anaplasma (5.00 %), Ehrlichia (2.14 %), Borrelia burgdorferi sensu lato (BBSL) (7.50 %), Babesia (0.18 %), and Theileria (5.89 %). Sequencing revealed the presence of 7 species of Rickettsia, 4 species of Anaplasma, 2 species of Ehrlichia, 2 species of BBSL, 1 species of Babesia, and 3 species of Theileria. Among the ticks, 6.43 % were co-infected with 2 pathogens, while 0.36 % exhibited co-infection with 3 pathogens. Significant correlations (P < 0.05) were observed between the prevalence of tick-borne pathogens and factors including tick species, sex, developmental stages, parasitic status, and blood-feeding status. The results highlight the diverse distribution of tick-borne pathogens in Qinghai Province, posing a significant threat to both local animal husbandry and human health. It underscores the need to enhance systematic monitoring of tick-borne pathogens in the local population and livestock.

Q fever is a zoonotic disease caused by infection with Coxiella burnetii (C. burnetii). Due to its atypical symptoms and the absence of specific detection methods, Q fever is underdiagnosed commonly. Herein, we report a case of Q fever confirmed by metagenomic next-generation sequencing (mNGS) in March 2024 in Guangdong Province, China. The patient initially experienced fever and was admitted to hospital six days later. Despite a series of laboratory tests conducted at the hospital, the pathogen remained undetermined. Ten days after admission, mNGS revealed that the patient was infected with C. burnetii. The patient subsequently underwent treatment with doxycycline and recovered well. Epidemiological investigation revealed that the patient had been exposed to sheep infected with C. burnetii without any protective measures in Jiangxi Province, China. Based on the comprehensive results of mNGS, exposure history, clinical manifestations and treatment response, the patient was confirmed as a Q fever case. As a neglected and underestimated illness, Q fever necessitates an elevation in awareness among medical staff and the public. The public should be encouraged to take personal protective measures when exposed to livestock. Further research is needed to explore the rational application of mNGS in the diagnosis of uncommon and unknown diseases.

In the last century, global pandemics have been primarily driven by respiratory infections, which consistently rank among the top 20 causes of death worldwide. The coronavirus disease 2019 (COVID-19) pandemic has underscored the intricate nature of managing multiple health crises simultaneously. In recent years, climate change has emerged as a major biosafety and population health challenge. Global warming and extreme weather events have intensified outbreaks of climate-sensitive infectious diseases, especially respiratory diseases. Influenza and COVID-19 have emerged as two of the most significant respiratory pandemics, each with unique epidemic characteristics and far-reaching consequences. Our comparative analysis reveals that while both diseases exhibit high transmission rates, COVID-19's longer incubation period and higher severity have led to more profound and prolonged socioeconomic disruptions than influenza. Both pandemics have highlighted the exacerbating effects of climate change, with extreme weather events intensifying the spread and impact of these diseases. The COVID-19 pandemic exposed vulnerabilities in global healthcare systems and economies on an unprecedented scale, outstripping the strain caused by influenza outbreaks. Importantly, the COVID-19 pandemic has not only reshaped global public health strategies but also significantly impacted the epidemiology of influenza. Despite these differences and associations, both diseases underscore the urgent need for robust pandemic preparedness and adaptable public health strategies. This review delineates the overlaps and distinctions between influenza and COVID-19, offering insights into future challenges and the critical steps needed to enhance healthcare system resilience and improve global responses to pandemics.

With the rapid advance in synthetic biology and the expanding field of synthetic genomics, the realization of a redesigned yeast genome has become an achievable milestone. Multiple eukaryotic chromosomes, meticulously designed and synthesized, are now being systematically integrated to create an entirely synthetic eukaryotic cell. This comprehensive review examines the fundamental design principles and construction strategies, highlighting critical technological breakthroughs in pursuing the first synthetic eukaryotic cell. Additionally, it underscores the critical contributions of the Sc2.0 project, which has provided essential tools and engineered cellular platforms that have significantly accelerated research and industrial progress. The ethical and legal implications arising from synthetic eukaryotic life are also explored, offering insights into future research directions for synthetic eukaryotic genomes. The remarkable advances in deoxyribonucleic acid synthesis hold immense potential, promising to unlock new opportunities across medicine, industry, agriculture, and research.