The re-emergence of Coxsackievirus A6 (CV-A6) as a predominant pathogen in hand, foot, and mouth disease (HFMD) underscores the need for ongoing molecular surveillance to clarify local evolutionary dynamics. This study aimed to characterize the genetic features of CV-A6 strains circulating in Baotou, Inner Mongolia, from 2023 to 2024. Throat swabs collected from HFMD patients were screened using real-time quantitative PCR; the VP1 region and complete genomes of representative CV-A6-positive samples were amplified and sequenced. Phylogenetic and recombination analyses were subsequently performed. Among 266 clinical specimens, 169 (63.53%) tested positive for enterovirus, of which 146 (86.39%) were identified as CV-A6. The local epidemic displayed an autumn-winter seasonality and predominantly affected children aged 4-6 years. Phylogenetic reconstruction of 133 VP1 sequences revealed that all Baotou CV-A6 isolates belonged to subgenotype D3c, and analysis of complete genomes identified a predominant recombinant form. These findings demonstrate that the D3c subgenotype, characterized by a specific recombinant structure, was responsible for HFMD outbreaks in Baotou during the study period, providing essential molecular evidence for regional public health strategies and vaccine development.

ObjectiveTo investigate the pathogen spectrum and epidemiological characteristics of influenza-like illness (ILI) in Guilin, China, from 2023 to 2024.MethodsBetween October 2023 and October 2024, 400 pharyngeal swabs were collected weekly from ILI patients and 18 respiratory pathogens were detected using quantitative real-time PCR (qPCR). Pathogen spectrum and epidemiological characteristics were analyzed.ResultsOf the 400 samples, the overall pathogen-positive rate was 74.0% (296/400). Among the detected pathogens, Influenza (Flu) was the main pathogen (44.0%, 176/400), followed by SARS-CoV-2 (12.3%, 49/400) and Mycoplasma pneumoniae (MP) (8.8%, 35/400). The detection rate is highest in the age group of 45–59 years old, reaching 91.7%. The detection rates for Flu, SARS-CoV-2, MP, HAdV, RSV, EV, and HPIV showed significant differences among age groups (p < 0.05). The peak period of positive detection rate was autumn and winter (Nov 2023–Mar 2024). Flu (H3N2 and IBV) dominated in autumn and winter, but was gradually replaced by SARS-CoV-2 and MP thereafter. By autumn 2024, SARS-CoV-2 and HRV were predominant. Co-infections were identified in 14.2% (42/296) of positive cases, with the combination of Flu and MP being the most common (19.0%).ConclusionDuring the study period, ILI in Guilin was primarily driven by Flu, which co-circulated with other pathogens including SARS-CoV-2 and MP, demonstrating distinct seasonal patterns and demographic distributions.

Objectives Acute respiratory infections (ARIs) remain a major global public health burden. This study aimed to characterize the longitudinal epidemiology, pathogen spectrum, and temporal patterns among ARI patients in Changshu, Jiangsu, China, from September 2021 to December 2024, encompassing the late COVID-19 pandemic and the subsequent post‑control era. Methods Nasopharyngeal swabs were collected from 4340 ARI patients attending eight sentinel hospitals. Seventeen respiratory pathogens were detected using real-time quantitative PCR. Demographic characteristics, clinical setting, age group, seasonality, monthly trends, and co-infection patterns were analyzed. Results Overall, 1309 of 4340 patients (30.16%) tested positive for at least one pathogen. Influenza virus was the most frequently detected pathogen (9.61% of all specimens), followed by human adenovirus (HAdV) (4.82%) and human coronavirus (HCoV) (4.15%). The detection rate varied significantly by age, with the highest rate in children aged 5–17 years (46.28%). The pathogen detection rates in autumn (32.90%) and winter (32.89%) were higher than those in spring (26.11%) and summer (27.93%). Co-infections were identified in 199 patients (15.20% of positive cases), predominantly influenza–coronavirus combinations. Temporal analysis revealed a marked influenza‑associated increase in March 2023, a sustained increase in Mycoplasma pneumoniae detections from November 2023 onward, and a multi‑pathogen co‑circulation (including coronavirus, rhinovirus, adenovirus, influenza, and parainfluenza) after April 2024. Conclusions This longitudinal surveillance documented temporal changes in respiratory pathogen circulation in Changshu, including an influenza resurgence in early 2023, rising M. pneumoniae activity in late 2023, and concurrent increases in multiple viruses during 2024. These findings highlight the value of sustained county‑level monitoring to detect emerging epidemiological changes and inform local public health responses.

Background Ticks are the second most significant vector of human pathogens worldwide, with 911 documented species globally and a broad distributed across China. Currently, over 160 tick-borne viruses (TBVs) have been identified, several of which pose substantial threats to human health, such as Dabie bandavirus, Jingmen tick virus, Alongshan virus, Songling virus, Beiji nairovirus, and Langya henipavirus, raising increasing global attention. Despite their significance, the diversity of TBVs in Beijing remains poorly characterized. Methods In this study, we conducted metagenomic sequencing on tick samples collected from Mentougou District, Beijing. The obtained reads were subjected to quality control, de novo assembly, and viral sequence identification, followed by phylogenetic and evolutionary analyses. Results Our results identified 19 distinct viral species spanning 12 families, including Hepelivirales, Solemoviridae,Mymonaviridae, Nodaviridae,Permutotetraviridae, Phenuiviridae,Rhabdoviridae, Tombusviridae,Totiviridae, Peribunyaviridae,Flaviviridae, Nodaviridae,Tymoviridae, Tombusviridae. Among these, six novel viruses from five virus families were discovered. A potential pathogen, Tick jingmen-like virus, was also detected in the selected pathogens. These findings underscore the remarkable diversity of RNA viruses harbored by ticks in Mentougou District. Conclusions Our research findings reveal a previously unrecognized diversity of tick-borne viruses in the Mentougou District, Beijing, and provide essential baseline data for informing future surveillance strategies and guiding prevention and control of tick-borne diseases in the Beijing metropolitan area.

ObjectivesTo evaluate the immune persistence and cross-immune response of elderly individuals after Omicron BA.5 infections.MethodThe neutralizing antibodies against WT, BA.5, XBB.1 and EG.5 strains were analyzed. The T/B-cell subsets’ responses were tested through intracellular cytokine staining and flow cytometry.ResultsThe neutralizing antibodies titers against WT and BA.5 strain, remaining high level for at least 6 months, were higher than that of both XBB.1 and EG.5 variants. The neutralizing antibodies of WT, BA.5, XBB.1, and EG.5 strains in the elderly were slightly lower than those in middle-age. The memory B cells decreased rapidly in the elderly, and Tfh, Th17 cells of the elderly continued to increase for only 3 months, while Tfh and Th17 cells increased in the middle-aged for over 6 months. For the elderly, after peptide stimulation, unswitched/switched memory B cells decreased, while double negative B cells displayed higher proliferation. The proportions of both naïve and Temra cells in CD4+ and CD8+ T cells declined, whereas those of Tcm and Tem cells elevated. In the meantime, both CD69+ and CD38+ T cells decreased, but the frequencies of PD-1+ and CTLA-4+ of CD4+ and CD8+ T cells showed an increasing trend. The proportions of PD-1+ and CTLA-4+ cells also increased in older people with long COVID symptoms at 3m post-infection.ConclusionsOmicron BA.5 infection induced lower neutralizing antibodies against XBB.1 and EG.5 variant. The decrease of memory B cells, CD69+ and CD38+T cells, as well as the increase of PD-1+, CTLA-4+ of CD4+/CD8+T cells and double negative B cells, indicate that sustained immune responses against BA.5 infection may wane more rapidly in elderly populations.

ObjectiveTo understand the epidemiology and evolutionary characteristics of human adenovirus (HAdV) infecting children in Yancheng, China, during the winter of 2023-2024.MethodsHAdV-positive throat swab samples were collected from pediatric patients in Yancheng. The Hexon, Penton base, and Fiber genes were amplified and sequenced for typing and phylogenetic analysis of HAdV.Results170 HAdV-positive samples were collected and identified from children with acute respiratory infection (ARI) in Yancheng. A total of 133 samples were successfully amplified and sequenced for Hexon, Penton base, and Fiber genes. Phylogenetic analysis showed that HAdV-B3 was the dominant circulating strain, and two strains of B21, one strain of C1 and one strain of C5 were also identified.ConclusionDuring the winter of 2023-2024, HAdV infecting children in Yancheng was mainly the B3 type.

Objective:To investigate the epidemiological characteristics and genetic profile of human bocavirus (HBoV) among patients with acute respiratory infection (ARI) in Yucheng, Henan, China. Methods:A total of 1,153 throat swabs were collected from ARI patients between March and June 2023. These samples were tested for 18 pathogens using quantitative chain reaction (qPCR). The VP1 gene were amplified and sequenced from HBoV-positive samples. The viral genetic characterization was analyzed by comparing the HBoV1 sequences with reference sequences. Results:Of the 1,153 samples, the detection rate of HBoV positive was 6.85%, primarily detected in May 2023. The majority of HBoV positive cases were found in children under 5 years old. Clinical manifestations in HBoV-positive patients predominantly were fever and cough, with a clinical diagnosis of lower respiratory tract infection. Other viruses were also detected in 20% of HBoV-positive samples. All HBoV sequences identified in this study belonged to HBoV1, with the Ib sublineage being the predominant strain circulating in Yucheng during March-June 2023. Conclusion:After the implementation of the optimized COVID-19 prevention and control strategy in December 2022, HBoV infection was prevalent in Yucheng, Henan in May-June 2023, mainly among children younger than 5 years old, especially those under 2 years old. The Ib sublineage of HBoV was the dominant circulating strain in Yucheng, Henan during March-June 2023.

IntroductionSeasonal human coronavirus NL63 (HCoV-NL63) is a frequently encountered virus linked to mild upper respiratory infections. However, its potential to cause more severe or widespread disease remains an area of concern. This study aimed to investigate a rare localized epidemic of HCoV-NL63-induced respiratory infections among pediatric patients in Guilin, China, and to understand the viral subtype distribution and genetic characteristics.MethodsIn this study, 83 pediatric patients hospitalized with acute respiratory infections and positive for HCoV-NL63 were enrolled. Molecular analysis was conducted to identify the viral subgenotypes and to assess genetic variations in the receptor-binding domain of the spiking protein.ResultsAmong the 83 HCoV-NL63-positive children, three subgenotypes were identified: C4, C3, and B. Notably, 21 cases exhibited a previously unreported subtype, C4. Analysis of the C4 subtype revealed a unique amino acid mutation (I507L) in the receptor-binding domain of the spiking protein, which was also observed in the previously reported C3 genotype. This mutation may suggest potential increases in viral transmissibility and pathogenicity.DiscussionThe findings of this study highlight the rapid mutation dynamics of HCoV-NL63 and its potential for increased virulence and epidemic transmission. The presence of a unique mutation in the C4 subtype, shared with the C3 genotype, raises concerns about the virus’s evolving nature and its potential public health implications. This research contributes valuable insights into the understanding of HCoV-NL63’s epidemiology and pathogenesis, which is crucial for effective disease prevention and control strategies. Future studies are needed to further investigate the biological significance of the observed mutation and its potential impact on the virus’s transmissibility and pathogenicity.

The symptoms of children infected with SARS-CoV-2 are mainly asymptomatic, mild, moderate, and a few severe cases. To understand the immune response characteristics of children infected with SARS-COV-2 who do not develop severe cases, 82 children infected with the SARS-CoV-2 delta strain were recruited in this study. Our results showed that high levels of IgG, IgM, and neutralization antibodies appeared in children infected with SARS-CoV-2. SARS-CoV-2 induced upregulation of both pro-inflammatory factors including TNF-α and anti-inflammatory factors including IL-4 and IL-13 in the children, even IL-10. The expression of INF-α in infected children also showed a significant increase compared to healthy children. However, IL-6, one of the important inflammatory factors, did not show an increase in infected children. It is worth noting that a large number of chemokines reduced in the SARS-CoV-2-infected children. Subsequently, TCR Repertoire, TCRβ bias, and preferential usage were analyzed on data of TCR next-generation sequencing from 8 SARS-CoV-2-infected children and 8 healthy controls. We found a significant decrease in TCR clonal diversity and a significant increase in TCR clonal expansion in SARS-CoV-2-infected children compared to healthy children. The most frequent V and J genes in SARS-CoV-2 children were TRBV28 and TRBJ2-1. The most frequently VβJ gene pairing in SARS-CoV-2 infected children was TRBV20-1-TRBJ2-1. The strong antiviral antibody levels, low expression of key pro-inflammatory factors, significant elevation of anti-inflammatory factors, and downregulation of many chemokines jointly determine that SARS-CoV-2-infected children rarely develop severe cases. Overall, our findings shed a light on the immune response of non-severe children infected with SARS-CoV-2.

We investigated spatial heterogeneity and diel variations in bacterioplankton and pico-nanoeukaryote communities, and potential biotic interactions at the extinction stage of the Ulva prolifera bloom in the Jiaozhou Bay, Yellow Sea. It was found that the presence of Ulva canopies significantly promoted the cell abundance of heterotrophic bacteria, raised evenness, and altered the community structure of bacterioplankton. A diel pattern was solely significant for pico-nanoeukaryote community structure. >50 % of variation in the heterotrophic bacterial abundance was accounted for by the ratio of Bacteroidota to Firmicutes, and dissolved organic nitrogen effectively explained the variations in cell abundances of phytoplankton populations. The factors representing biotic interactions frequently contributed substantially more than environmental factors in explaining the variations in diversity and community structure of both bacterioplankton and pico-nanoeukaryotes. There were higher proportions of eukaryotic pathogens compared to other marine systems, suggesting a higher ecological risk associated with the Ulva blooms.

In August 2023, the National Health Science and Education Commission of the National Health Commission issued Notice No.24[2023], officially releasing the " Catalogue of Pathogenic Microorganisms Transmitted to Human Beings". This is to better implement the relevant regulations of the Biosafety Law of the People′s Republic of China and the Biosafety Management Regulations for Pathogenic Microbial Laboratories. With the continuous emergence of new pathogenic microorganisms, updated understanding of existing pathogenic microorganisms, and deepening laboratory biosafety research, the original " List of Pathogenic Microorganisms Transmitted from Human Beings" cannot meet the needs, so the " Catalogue of Pathogenic Microorganisms Transmitted from Human Beings" has been issued. This article aims to provide a detailed interpretation of the virus section of the Catalogue, including its background, principles, processes, and main content, in order to facilitate a better understanding of the Catalogue.

Viral myocarditis (VMC) is a common disease characterized by cardiac inflammation. AC-73, an inhibitor of CD147, disrupts the dimerization of CD147, which participates in the regulation of inflammation. To explore whether AC-73 could alleviate cardiac inflammation induced by CVB3, mice were injected intraperitoneally with AC-73 on the fourth day post-infection (dpi) and sacrificed on the seventh dpi. Pathological changes in the myocardium, T cell activation or differentiation, and expression of cytokines were analyzed using H&E staining, flow cytometry, fluorescence staining and multiplex immunoassay. The results showed that AC-73 alleviated cardiac pathological injury and downregulated the percentage of CD45+CD3+ T cells in the CVB3-infected mice. The administration of AC-73 reduced the percentage of activated CD4+ and CD8+ T cells (CD69+ and/or CD38+) in the spleen, while the percentage of CD4+ T cell subsets in the spleen was not changed in the CVB3-infected mice. In addition, the infiltration of activated T cells (CD69+) and macrophages (F4/80+) in the myocardium also decreased after the AC-73 treatment. The results also showed that AC-73 inhibited the release of many cytokines and chemokines in the plasma of the CVB3-infected mice. In conclusion, AC-73 mitigated CVB3-induced myocarditis by inhibiting the activation of T cells and the recruitment of immune cells to the heart. Thus, CD147 may be a therapeutic target for virus-induced cardiac inflammation.

Thirty-six strains of 10 RNA viruses belonging to 4 viral families, including 3 viruses of Iflaviridae , 4 viruses of Phenuiviridae , 2 viruses of Nairoviridae , and 1 virus of Chuviridae , were identified from five tick species in Qingdao, China. A diversity of tick-borne viruses from hares and hedgehogs in Qingdao was found in this study.

Abstract Background To investigate the impact of the coronavirus disease 2019 (COVID-19) outbreak on the prevalence of respiratory viruses among pediatric patients with acute respiratory infections in Xuzhou from 2015–2021. Methods Severe acute respiratory infection (SARI) cases in hospitalized children were collected from 2015–2021 in Xuzhou, China. Influenza virus(IFV), respiratory syncytial virus (RSV), human parainfluenza virus type 3(hPIV-3), human rhinovirus (hRV), human adenovirus(hAdV), human coronavirus(hCoV) were detected by real-time fluorescence polymerase chain reaction(RT-qPCR), and the results were statistically analyzed by SPSS 23.0 software. Results A total of 1663 samples with SARI were collected from 2015–2021, with a male-to-female ratio of 1.67:1 and a total virus detection rate of 38.5% (641/1663). The total detection rate of respiratory viruses decreased from 46.2% (2015–2019) to 36% (2020–2021) under the control measures for COVID-19 (P < 0.01). The three viruses with the highest detection rates changed from hRV, RSV, and hPIV-3 to hRV, RSV, and hCoV. The epidemic trend of hPIV-3 and hAdV was upside down before and after control measures(P < 0.01); however, the epidemic trend of RV and RSV had not changed from 2015 to 2021(P > 0.05). After the control measures, the detection rate of hPIV-3 decreased in all age groups, and the detection rate of hCoV increased in all except the 1 ~ 3 years old group. Conclusions Implementing control measures for COVID-19 outbreak curbed the spread of respiratory viruses among children as a whole. However, the epidemic of RV and RSV was not affected by the COVID-19 control policy.

Objective:A mouse model of pancreatitis induced by coxsackievirus B3 (CVB3) was established. The pathological change of pancreas and the infiltration of Th17/Treg cells were observed.Methods:The BALB/c mice were inoculated intraperitoneally with CVB3 to induce acute viral pancreatitis model. Then the pathological changes of pancreas were observed by HE staining; the viral RNA load and relative expression of cytokines (IFN-γ, IL-6 and IL-17) mRNA were detected by q-PCR; the proportion of infiltrated CD45 + CD3 + T cells, CD4 + and CD8 + T cells, Th17 and Treg cells in the pancreas was determined by flow cytometry. Results:Three days after CVB3 infection, the viral RNA load in pancreas was the highest (0.96±0.18) and gradually decreased with prolongation of infection. Compared with the 3 dpi group, the viral RNA load in pancreas was decreased (0.96±0.18 vs. 0.62±0.14) at 7 dpi, but there was no statistically significant difference. In addition, the infiltration of immune cell in pancreas increased significantly after 7dpi and the pathological score >2. The percent of infiltrated Th17 cells (1.05±0.21 vs. 22.13±5.79) and Treg cells (3.11±0.78 vs. 8.25±1.30) among CD4 + T cells significantly increased after infection (P<0.05), and the Th17/Treg also increased (P<0.01). Compared with the control group, the relative mRNA expression of IFN-γ (1.05±0.23 vs. 672.6±47.67), IL-6 (1.00±0.38 vs. 68.28±4.57), and IL-17 (1.01±0.11 vs. 54.15±7.94) in pancreas increased at 7 days after CVB3 infection ( P<0.01). Conclusions:The infiltration of Th17/Treg cells and the expression of related cytokines related cytokines IL-6 and IL-17 mRNA were upregulated in pancreas, which promoted the process of CVB3-induced pancreatitis.

In this journal, Liu and colleagues showed the potential efficacy of a recombinant protein vaccine for COVID-19 as a boost strategy.1 However, the rapid emergence of immune-evasive SARS-CoV-2 variants, especially the Omicron sub-variants, called for development of vaccines with cross-protection to a broad-spectrum of variants. SCTV01C is a recombinant bivalent vaccine comprised of trimeric spike extracellular domain (S-ECD) of SARS-CoV-2 variants Alpha (B.1.1.7) and Beta (B.1.351), and adjuvanted with SCT-VA02B, a squalene-based oil-in-water emulsion.

Objective:To analyze the association of respiratory syncytial virus infection with meteorological factors and to predict and explain the trends.Methods:Data of cases with severe acute respiratory infections in hospitalized children in Xuzhou City were collected from 2015-2021. Respiratory syncytial virus (RSV) was detected by real-time fluorescence polymerase chain reaction. The result were statistically analyzed using SPSS 26.0 software, including constructing a negative binomial regression model to explore meteorological factors that impact RSV detection and a multivariate time series model to predict its epidemiological trend from 2020 to 2021.Results:A total of 1 663 samples of children with severe acute respiratory infections were collected from 2015to 2021, of which 218 (13.1%) were positive for RSV. Seasonal effects on RSV detection were evident: there was a 1-year cycle with a peak in winter (December-February) and a trough in summer (June-August). The negative binomial regression analysis showed that monthly mean temperature, monthly mean relative humidity, and monthly total sunshine hours may influenced RSV detection. The prediction result of the time series model with sunshine hours as the covariate showed that the prediction was better for 2020, and the actual values were close to the predicted values. The expected trends in 2021 were consistent, but the actual values were higher than predicted.Conclusions:Monthly mean temperature, monthly mean relative humidity, and monthly total sunshine hours may influence RSV detection in the Xuzhou region.A prediction model can be built using data from 2015-2019, where deviations in the predicted values for 2021, reflecting that disease prevalence is multifactorial correlated, suggest a possible rise in RSV prevalence in the future.

Objective. To detect viral load in human cytomegalovirus (HCMV) infection children after hematopoietic stem cell transplant (HSCT) by chip digital PCR (cdPCR). Methods. The plasmid pUC57-UL83 containing the HCMV-UL83 gene and HCMV AD169 strain were used to evaluate the sensitivity of cdPCR. Either HSV-1, HSV-2, VZV, EBV, HHV-6, or HHV-7 was used to evaluate the specificity of HCMV cdPCR. The cdPCR was compared with quantitative PCR (qPCR) by detecting HCMV infection in 125 children's whole blood samples following HSCT. Results. The limit of detection (LOD) of HCMV cdPCR was 103 copies/ml and the qPCR LOD was 297 copies/ml for plasmid pUC57-UL83. The result of HCMV cdPCR was 146 copies/ml for the HCMV AD169 strain, indicating that the sensitivity of cdPCR was higher than that of qPCR. There is no cross-reaction between HCMV cdPCR and other herpes viruses. The incidence of HCMV infection was 30.40% in 125 children following HSCT by cdPCR. The range of the HCMV viral load was from 107 copies/ml to 6600 copies/ml by cdPCR. Conclusions. cdPCR is more sensitive than qPCR for detecting HCMV viral load. Furthermore, the cdPCR could be used to detect the viral load of HCMV infection before or after HSCT in children.

As an alternative mechanism for cap-dependent (m7GpppN) translation, internal ribosome entry site (IRES)-dependent translation has been observed in the 5' untranslated regions (5' UTR) and coding regions of a number of viral and eukaryotic mRNAs. In this study, a series of 5' terminal truncated structural protein genes that were fused with GFP was used to screen for potential IRESs, and IRESs were identified using a bicistronic luciferase vector or GFP expression vector possessing a hairpin structure. Our results revealed that a putative IRES was located between nt 1982 and 2281 in the VP3 coding region of the human rhinovirus 16 (HRV16) genomes. We also demonstrated that effective IRES-initiated protein expression in vitro did not occur through splicing sites or cryptic promoters. We confirmed that thapsigargin (TG), an inducer of endoplasmic reticulum stress (ERS), facilitated increased IRES activity in a dose-dependent manner. Additionally, the secondary structure of the IRES was predicted online using the RNAfold web server.

Objectives: This study assessed the incidence and resistance of Mycoplasma pneumoniae (MP) in children in Qingdao, China, in 2019. Methods: We detected MP infection in 78 pharyngeal swabs from children with pneumonia by qPCR. The RepMP4 element in the P1 adhesin gene, domain V of the 23S rRNA gene, and the L4/L22 ribosomal pro-teins were amplified by nested PCR. Evolutionary analysis was conducted based on the P1 gene sequence. Resistance mutations in domain V of the 23S rRNA gene and L4/L22 ribosomal proteins were analysed. Results: The incidence of MP infection in children with pneumonia was 59.0% (46/78). The mean duration of MP infection was longer than that of non-MP infection. According to P1 gene sequencing of 21 samples, 12 (57.1%) were type 1 and 9 (42.9%) were type 2. Drug resistance mutations A2063G in domain V of 23S rRNA gene and T508C in L22 were identified from all sequenced MP. However, mutations at positions 2064 and 2617 were not found in this study. C162A mutation appeared in most type 2 samples. A430G mutation appeared in one type 1 sample and in several type 2 samples. T279C mutation in L22 was mostly found in type 2 samples. Conclusion: The incidence of MP infection was 59.0% in children with pneumonia in Qingdao in 2019. Type 1 MP infection was slightly more common than type 2, indicating that the genotype of MP is grad-ually shifting from type 1 to type 2. Macrolide resistance mutation A2063G could be detected in all sequenced MP. (c) 2021 The Author(s). Published by Elsevier Ltd on behalf of International Society for Antimicrobial Chemotherapy. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )