Respiratory syncytial virus (RSV) is one of the most common viruses leading to lower respiratory tract infections (LRTIs) in children and elderly individuals worldwide. Although significant progress in the prevention and treatment of RSV infection was made in 2023, with two anti-RSV vaccines and one monoclonal antibody approved by the FDA, there is still a lack of postinfection therapeutic drugs in clinical practice, especially for the pediatric population. In recent years, with an increasing understanding of the pathogenic mechanisms of RSV, drugs and drug candidates, have shown great potential for clinical application. In this review, we categorize and discuss promising anti-RSV drug candidates that have been in preclinical or clinical development over the last five years.

Rotavirus infections cause severe gastroenteritis and dehydration in young children and animals worldwide, leading to high rates of morbidity and mortality, predominantly in low- and middle-income countries. In the past decade, substantial progress has been made in the development and implementation of rotavirus vaccines, which have been essential in alleviating the global burden of this disease, not only in human being but also in livestock species like calves and piglets, where these infections can cause significant economic losses. By synthesizing the latest research and real-world evidence, this review article is designated to provide deep insights into the current state of rotavirus vaccine technology and its global implementation as well as the application of rotavirus vaccines in veterinary settings and their importance in controlling zoonotic transmission and maintaining food security.

The H9N2 subtype avian influenza virus (AIV) continues to propagate and undergo evolution within China, thereby posing a significant threat to the poultry industry. This study encompassed the collection of 436 samples and swabs in East China over the period spanning 2018 to 2019, from which 31 strains of the H9N2 subtype viruses were isolated and purified. We revealed that the HA and NA genes of the 31 isolates categorized within the Y280 branch, while the PB2 and M genes were associated with the G1 branch, and the remaining genes aligned with the F/98 branch. Despite this alignment, antigenic mapping demonstrated differences between the 2018 and 2019 strains, with the early vaccine strains displaying low serological reactivity toward these isolates. Notably, the CK/SH/49/19 isolate exhibited lethality in mice, characterized by a PB2 E627V mutation and a HA deletion at amino acid position 217. Mechanistically, in vitro studies showed that the influenza virus CK/SH/49/19 carrying PB2 627V and HA 217M mutations displayed enhanced replication capacity, attributed to the heightened activity of the polymerase with PB2 627V. Moreover, the absence of the amino acid at the HA 217 site obstructed viral adsorption and internalization, resulted in lower activation pH, and impeded the virus budding process. Critically, in vivo experiments revealed that CK/SH/49/19 (PB2 627V, HA 217Δ) triggered a robust activation of interferon response and interferon-stimulated genes. This study furnished a theoretical foundation for the scientific prevention and control strategies against H9N2 subtype avian influenza.

On 30 January 2024, China announced the first human case of H10N5 influenza infection. Prior to this, human cases of H10N7 and H10N8 had been reported. It is now appropriate to re-examine the evolution and future epidemiological trends of the H10 and N5 subtypes of avian influenza viruses (AIVs). In this study, we analyzed the reassortment characteristics of the first human-derived H10N5 AIV (A/Zhejiang/ZJU01/2023), as well as the evolutionary dynamics of the wild bird-derived H10 and N5 subtypes of AIVs over the past decade. Our findings indicate that the human-derived H10N5 AIV exhibited low pathogenicity. A/bean_goose/Korea/KNU-10/2022(H10N7) and A/mallard/Novosibirsk_region/962k/2018(H12N5) were identified as the potential reassortment parents. The virus has existed since 2022 and several isolations have been reported in Bangladesh. Phylogenetic analysis showed that H10Ny and HxN5 AIVs in China are clustered differently based on the East Asian-Australian (eastern) and Central Asian-Indian (western) migratory flyways. The H10Ny and HxN5 AIV reassortant strains may cause human infections through accidental spillover. It is possible that another center of AIV evolution, mutation, and reassortment may be developing along the migratory flyways in northeastern Asia, distinct from Europe, the Americas, and China's Yangtze River Delta and Pearl River Delta, which should be closely monitored to ensure the safety of the public.

Acute respiratory tract infections (ARTIs) are among the leading causes of morbidity and mortality in children worldwide. Human adenovirus (HAdV) infections are estimated to account for at least 5% of pediatric ARTIs. The circulated genotypes of HAdV and the correlation between genotype and clinical manifestations in Wuhan, China, before and after the complete relaxation of nonpharmaceutical interventions against severe acute respiratory syndrome coronavirus 2, remain unknown. Here, 101 HAdV strains were isolated from throat swab samples collected from hospitalized children with ARTIs who tested positive for HAdV nucleic acid. Of these, sixty-six strains from 2022 and 23 strains from 2023 were successfully genotyped and subjected to phylogenetic analysis based on the hexon, penton base, and fiber genes. Six genotypes, B3, C1, C2, C5, C104, and C108 were identified. HAdV-B3 (84.85%) was the most prevalent type in 2022, while HAdV-C (86.96%), including C1, C2, C108, and C104, was the most prevalent in 2023. These strains were phylogenetically related to strains from Japan, China, and the United States in recent years. When comparing clinical characteristics, pediatric patients infected with B3, C1, C2, C5, C104, or C108 exhibited similar clinical manifestations, primarily fever and cough, but varying interleukin (IL)-10 levels. In conclusion, from June 2022 to September 2023, the circulated genotypes of HAdV in Wuhan included B3, C1, C2, C108, C5, and C104. The endemic pattern of HAdV in Wuhan, China, shifted from species B as the dominant type in 2022 to species C in 2023.

Traditional Chinese medicine has unique advantages in preventing and treating COVID-19, and Fuzheng Jiedu decoction (FZJDD) was reported to be effective against COVID-19 in clinical trials. To investigate the potential mechanisms and material basis of FZJDD against SARS-CoV-2, we performed SARS-CoV-2 target protein inhibition analyses and a metabolite full spectrum analysis of FZJDD. Interestingly, FZJDD was found to block the binding of SARS-CoV-2 Spike protein with the receptor ACE2 and inhibit the activity of SARS-CoV-2 3CLpro. Moreover, FZJDD can regulate the TNF and the MAPK signaling pathway to inhibit the inflammatory response and alleviate the "cytokine storm". A total of 298 compounds were identified in FZJDD, among them, caffeic acid and octyl gallate were found to be the potential therapeutic agents of FZJDD. Importantly, FZJDD can broadly inhibit coronavirus infection, including SADS-CoV and porcine epidemic diarrhea virus (PEDV) live viruses, SARS-CoV, MERS-CoV, and SARS-CoV-2 mutant pseudotyped viruses, which might be ascribed to the broad-spectrum anti-coronavirus activity of caffeic acid and octyl gallate. In conclusion, this study reveals the mechanisms and material basis of FZJDD against SARS-CoV-2 and identifies the broad-spectrum anti-coronavirus activity of FZJDD for the first time. Our data provide empirical evidence for the development and application of FZJDD.

Influenza, a highly contagious respiratory infectious disease caused by an influenza virus, is a threat to public health worldwide. Avian influenza viruses (AIVs) have the potential to cause the next pandemic by crossing the species barrier through mutation of viral genome. Here, we investigated the pathogenicity of AIVs obtained from South Korea and Mongolia during 2018-2019 by measuring viral titers in the lungs and extrapulmonary organs of mouse models. In addition, we assessed the pathogenicity of AIVs in ferret models. Moreover, we compared the ability of viruses to replicate in mammalian cells, as well as the receptor-binding preferences of AIV isolates. Genetic analyses were finally performed to identify the genetic relationships and amino acid substitutions between viral proteins during mammalian adaptation. Of the 24 AIV isolates tested, A/Mallard/South Korea/KNU2019-34/2019 (KNU19-34; H1N1) caused severe bodyweight loss and high mortality in mice. The virus replicated in the lungs, kidneys, and heart. Importantly, KNU19-34-infected ferrets showed high viral loads in both nasal washes and lungs. KNU19-34 replicated rapidly in A549 and bound preferentially to human like α2,6-linked sialic acids rather than to avian-like α2,3-linked sialic acids, similar to the pandemic A/California/04/2009 (H1N1) strain. Gene segments of KNU19-34 were distributed in Egypt and Asia lineages from 2015 to 2018, and the virus had several amino acid substitutions compared to H1N1 AIV isolates that were non-pathogenic in mice. Collectively, the data suggest that KNU19-34 has zoonotic potential and the possibility of new mutations responsible for mammalian adaptation.

In-utero exposure to Zika virus (ZIKV) could lead to miscarriage, preterm birth and children with congenital Zika syndrome. This study aimed at estimating the burden of ZIKV infection among pregnant women from 21 Feb and 19 April 2022. ELISA and microneutralization test (MNT) were used to detect the presence of ZIKV antibodies. All the ZIKV IgM positive samples were retested for dengue virus (DENV) and ZIKV RNA, and DENV NS1 antigen. Additionally, all the samples with ZIKV neutralizing antibody (nAb) were retested for DENV antigen, antibody and nucleic acid. Of 200 pregnant women, 16.5% were positive for ZIKV IgM, 10% were positive for IgG, and 23% were found to have nAb in their serum. Among the 46 ZIKV nAb-positive women, 52.2% and 10.9% were recent and previous ZIKV infections, respectively, while 6.5% had previous DENV infections. Although no recent DENV infection was detected, recent and previous ZIKV/DENV co-infections were 13.0% and 17.4%, respectively. Two participants had recent secondary ZIKV infections, while 39.1% had prolonged lifelong immunity against the virus. Recent ZIKV infection rates were significantly higher among sexually active females aged 20-29 years than other age groups and women who had no pre-knowledge of the virus. ZIKV infection is not significantly associated with early and late trimester, but the risk of ZIKV infection is highest in the women in first trimester of pregnancy. The grand-multiparous women are at higher risk of ZIKV infections than other categories. In addition, women with and without a history of children with paralysis, brain defects (microcephaly) and stillbirths (claimed by the women) had both recent and past ZIKV infections. Monotypic recent, secondary and past ZIKV and co-infections with DENV and ZIKV were detected among the asymptomatic and symptomatic pregnant women.

The long-term effects of combined antiretroviral therapy (ART) on liver fibrosis patterns in adults living with HIV and chronic hepatitis B virus (HBV) are not well understood. Therefore, this study aimed to investigate the trajectories of liver fibrosis and identify the associations of baseline variables with different patterns of liver fibrosis evolution. A total of 333 individuals with HIV/HBV co-infection and undergoing long-term ART were enrolled in this study. Demographic, clinical, and biochemical data were collected at baseline and during annual visits. Group-based trajectory models (GBTMs) were used to detect the patterns of liver fibrosis evolution based on longitudinal data of fibrosis-4 (Fib-4) and aspartate aminotransferase to platelet ratio index (APRI) scores. Logistic regression analysis was performed to identify baseline predictors of liver fibrosis evolution. The median age of all participants was 33 years. Among them, 89.5% initially received TDF-containing ART. GBTMs identified two distinct patterns of liver fibrosis evolution using either APRI or Fib-4 scores. The majority of individuals (78.5% for APRI and 75.3% for Fib-4; pattern A) showed stable or low fibrosis with no progression, while the remaining participants showed regression from high fibrosis levels (21.5% for APRI and 24.7% for Fib-4; pattern B). Pattern A participants were younger and had higher CD4+ cell counts, higher lymphocyte cell counts, higher white blood cell counts, and lower platelet counts at baseline compared to pattern B participants. For HIV/HBV co-infected patients with varying degrees of initial liver fibrosis, long-term ART has shown distinct patterns of alleviating liver fibrosis.

A switch from avian-type α-2,3 to human-type α-2,6 receptors is an essential element for the initiation of a pandemic from an avian influenza virus. Some H9N2 viruses exhibit a preference for binding to human-type α-2,6 receptors. This identifies their potential threat to public health. However, our understanding of the molecular basis for the switch of receptor preference is still limited. In this study, we employed the random forest algorithm to identify the potentially key amino acid sites within hemagglutinin (HA), which are associated with the receptor binding ability of H9N2 avian influenza virus (AIV). Subsequently, these sites were further verified by receptor binding assays. A total of 12 substitutions in the HA protein (N158D, N158S, A160N, A160D, A160T, T163I, T163V, V190T, V190A, D193N, D193G, and N231D) were predicted to prefer binding to α-2,6 receptors. Except for the V190T substitution, the other substitutions were demonstrated to display an affinity for preferential binding to α-2,6 receptors by receptor binding assays. Especially, the A160T substitution caused a significant upregulation of immune-response genes and an increased mortality rate in mice. Our findings provide novel insights into understanding the genetic basis of receptor preference of the H9N2 AIV.

• Analyzed the outbreak situation and viral characteristics of the newly H5N1 highly pathogenic avian influenza (HPAI) virus. • The current approval and research and development of the H5N1 HPAI vaccines were summarized. • Proposed vaccine development approaches against newly H5N1 virus, e.g. adjuvanted vaccine, mRNA vaccine, multivalent vaccine. • Discussed other prevention and control strategies, e.g. poultry vaccination, global surveillance and comprehensive testing.

Virus-encoding RNA-dependent RNA polymerase (RdRp) is essential for genome replication and gene transcription of human coronaviruses (HCoVs), including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We previously identified the interaction between the catalytic subunit NSP12 of SARS-CoV-2 RdRp and the host protein CREB-regulated transcription coactivator 3 (CRTC3), a member of the CRTC family that regulates cyclic AMP response element-binding protein (CREB)-mediated transcriptional activation. Currently, the implication of CRTC3 in the pathogenesis of HCoVs is poorly understood. Herein, we demonstrated that CRTC3 attenuates RdRp activity and SARS-CoV-2 genome replication, therefore reducing the production of progeny viruses. The interaction of CRTC3 with NSP12 contributes to its inhibitory effect on RdRp activity. Furthermore, we expanded the suppressive effects of two other CRTC family members (CRTC1 and CRTC2) on the RdRp activities of lethal HCoVs, including SARS-CoV-2 and Middle East respiratory syndrome coronavirus (MERS-CoV), along with the CREB antagonization. Overall, our research suggests that CRTCs restrict the replication of HCoVs and are antagonized by CREB, which not only provides new insights into the replication regulation of HCoVs, but also offers important information for the development of anti-HCoV interventions.

Human adenoviruses (HAdVs) are highly contagious pathogens with various genotypes implicated in acute respiratory disease (ARD) and linked to fatality, especially in immunosuppressed patients, young children, and military recruits. Currently, no vaccines or specific drugs are approved for clinical use. The hosts of adenoviruses are strictly species-specific, which strongly limits the development of vaccines and drugs against HAdVs. In this study, immunocompetent BALB/c mice were challenged with different doses of human adenovirus type 5 (HAdV-5) via tail intravenous injection (i.v.). All mice challenged with a high dose of HAdV-5 (3.2 ​× ​10 TCID/kg) died within 3-5 days, while those receiving a low dose of HAdV-5 (8 ​× ​10 or 4 ​× ​10 TCID/kg) survived. Interestingly, among the mice receiving a medium dose of HAdV-5 (1.6 ​× ​10 TCID/kg), 60% (n ​= ​3/5) of male mice died, while all female mice survived. This suggests that male mice may be more susceptible to HAdV-5 infection than female mice, consistent with clinical findings in children. HAdV-5 DNA was mainly distributed in the liver, followed by the spleen and lung. Pathological changes were observed in the lung, liver, and spleen, with severity increasing in correlation with the virus challenge dosage. Transcriptome and qPCR analyses of the liver indicated that the down-regulated expression of the H2-Aa, H2-Ea-ps, CD74, and H2-Eb1 genes in male mice, as well as the AHR gene in female mice, may contribute to the observed higher mortality rates in male mice. Therefore, this effective, feasible, and cost-efficient mouse model could serve as a candidate for evaluating HAdV vaccines and anti-adenovirus therapeutics.

Severe fever with thrombocytopenia virus (SFTSV), an emerging tick-borne bandavirus, poses a significant public health threat in rural China. Since 2021, an increase of local cases has been noted in the rural-urban fringe of Beijing. This study aimed to assess the formation of natural foci in urban areas by conducting a field survey of ticks and hedgehogs from the second to fifth ring roads of Beijing. Our survey revealed a diverse tick population in city parks, including the major SFTSV vector, Haemaphysalis longicornis. Parthenogenetic H. longicornis, known for its role in the rapid spread of SFTSV, was identified in key locations such as Beihai Park and Taoranting Park, near the Forbidden City. Notably, high SFTSV seroprevalence and RNA prevalence were found in hedgehogs and parasitic ticks in the center of Beijing. Phylogenetic analyses of SFTSV RNA and mitochondrial sequences of parthenogenetic H. longicornis ticks revealed the existence of diverse lineages of SFTSV and H. longicornis ticks within Beijing, suggesting multiple invasion events happened. These findings reveal the circulation of SFTSV in central Beijing, highlighting the need for urgent attention and enhanced surveillance measures.

Ligularia jaluensis is an important medicinal and ornamental plant in China. However, the viruses capable of infecting Ligularia jaluensis remains unknown. Here, we identified a novel carlavirus, tentatively named ligularia jaluensis carlavirus (LJCV), as well as a known iris severe mosaic virus (ISMV), in L. jaluensis plants displaying chlorosis and yellow ring spot symptoms, using RNA-seq analysis. The LJCV genome consists of an 8497 ​nt positive-sense, single-stranded RNA [excluding the poly(A) tail], and contains six open reading frames (ORFs). Phylogenetic analyses based on the full-length genome and RNA-dependent RNA polymerase (RdRp) amino acid (aa) sequences revealed that LJCV clusters within an evolutionary branch alongside known viruses in the Carlavirus genus. The RdRp protein encoded by ORF1 of LJCV shared 45.38%-67.41% identity with the corresponding proteins of eight closely related carlaviruses. ORFs 2-4 constitute the triple gene block (TGB), with TGBp1 and TGBp3 localized in the endoplasmic reticulum (ER), while TGBp2 is localized at plasmodesmata (PD) and facilitates viral intercellular movement, as demonstrated by its ability to complement the potato virus X with movement-deficient mutant (PVX-Δp25-GFP). Additionally, ORF6 encodes a cysteine-rich protein (CRP) that is localized in the chloroplast and functions as a viral pathogenicity factor, inducing severe viral symptoms in the heterologous PVX expression system. Furthermore, we successfully constructed an infectious cDNA clone of LJCV, and found that it can infect Nicotiana benthamiana plants through mechanical inoculation or agrobacterium-mediated infiltration of the LJCV infectious clone. These findings enhance our understanding of the characteristics and host range of carlaviruses, as well as the viruses capable of infecting L. jaluensis.

Host ANP32 family proteins are crucial for maintaining the activity of influenza RNA polymerase and play an important role in the cross-species transmission of influenza viruses. To date, the molecular properties of equine ANP32 (eqANP32) protein are poorly understood, particularly the mechanisms that affect equine influenza virus (EIV) RNA polymerase activity. Here, we found that there are six alternative splicing variants of equine ANP32A (eqANP32A) with different levels of expression. Further studies showed that these six splicing variants of eqANP32A supported the activity of EIV RNA polymerase to varying degrees, with the variant eqANP32A_X2 having the highest expression abundance and exhibiting the highest support of polymerase activity. Sequence analysis demonstrated that the differences in the N-Cap regions of the six splicing variants significantly affected their N-terminal conformation, but did not affect their ability to bind RNA polymerase. We also demonstrated that there is only one transcript of eqANP32B, and that this transcript showed only very low support to the EIV RNA polymerase. This functional defect in eqANP32B is caused by the sequence of the 110-259 amino acids at its C-terminus. Our results indicated that it is the eqANP32A_X2 protein that mainly determines the efficiency of the EIV replication in horses. In conclusion, our study parsed the molecular properties of eqANP32 family proteins and revealed the sequence features of eqANP32A and eqANP32B, suggesting for the first time that the N-cap region of ANP32A protein also plays an important role in supporting the activity of the influenza virus polymerase.