Potential Recombination Events Research Articles

Genetic characteristics of human parainfluenza viruses 1-4 associated with acute lower respiratory tract infection in Chinese children, during 2015-2021.

Human parainfluenza viruses (HPIVs) are a significant cause of acute lower respiratory tract infections (ALRTIs) among young children and elderly individuals worldwide. The four types of HPIVs (HPIV1-4) can cause recurrent infections and pose a significant economic burden on health care systems globally. However, owing to the limited availability of complete genome sequences, the genetic evolution of these viruses and the development of vaccines and antiviral treatments are hampered. To address this issue, this study utilized next-generation sequencing to obtain 156 complete genome sequences of HPIV1-4, which were isolated from hospitalized children with ALRTIs in six regions of China between 2015 and 2021. This study revealed multiple clades, lineages, or sublineages of HPIVs circulating in mainland China, with a novel clade D of HPIV1 identified as geographically restricted to China. Moreover, this study identified the endemic dominant genotype of HPIV3, lineage C3, which has widely spread and continuously circulated in China. Bioinformatic analysis of the genome sequences revealed that the proteins of HPIV3 possessed the most variable sites, with the P protein showing more diversity than the other proteins among all types of HPIVs. The HN proteins of HPIV1-3 are all under negative/purifying selection, and two amino acid substitutions in the HN proteins correspond to known mAb neutralizing sites in the two HPIV3 strains. These findings provide crucial insights into the genetic diversity and evolutionary dynamics of HPIVs circulating among children in China and may facilitate research on the molecular diagnosis, vaccine development, and surveillance of HPIVs.IMPORTANCEPhylogenetic analysis revealed the prevalence of multiple clades, lineages, or sublineages of human parainfluenza viruses (HPIVs) circulating in mainland China. Notably, a unique evolutionary branch of HPIV1 containing only Chinese strains was identified and designated clade D. Furthermore, in 2023, HPIV3 strains from Pakistan and Russia formed a new lineage within clade C, named C6. The first HPIV4b sequence obtained in this study from China belongs to lineage C2. Evolutionary rate assessments revealed that both the HN and whole-genome sequences of HPIV3 presented the lowest evolutionary rates compared with those of the other HPIV types, with rates of 6.98E-04 substitutions/site/year (95% HPD: 5.87E-04 to 8.25E-03) and 5.85E-04 substitutions/site/year (95% HPD: 5.12E-04 to 6.62E-04), respectively. Recombination analysis revealed a potential recombination event in the F gene of an HPIV1 strain in this study. Additionally, all the newly obtained HPIV1-3 strains exhibited negative selection pressure, and two mutations were identified in the HN protein of two HPIV3 strains at monoclonal antibody-binding sites.

Genetic diversity and phylogeographic dynamics of avihepadnavirus: a comprehensive full-length genomic view.

Avihepadnavirus is a genus of the Hepadnaviridae family. It primarily infects birds, including species of duck, geese, cranes, storks, and herons etc. To understand the genetic relatedness and evolutionary diversity among avihepadnavirus strains, a comprehensive analysis of the available 136 full-length viral genomes (n = 136) was conducted. The genomes were classified into two major genotypes, i.e., GI and GII. GI viruses were further classified into 8 sub-genotypes including DHBV-I (duck hepatitis B virus-I), DHBV-II (Snow goose Hepatitis B, SGHBV), DHBV-III, RGHBV (rossgoose hepatitis B virus), CHBV (crane hepatitis B virus), THBV (Tinamou hepatitis B virus), STHBV (stork hepatitis B virus), and HHBV (Heron hepatitis B virus). DHBV-I contains two sub-clades DHBV-Ia and DHBV-Ib. Parrot hepatitis B virus (PHBV) stains fall into GII which appeared as a separate phylogenetic branch/clade. All the subtypes of viruses in GI and GII seem to be genetically connected with viruses of DHBV-I by multiple mutational steps in phylogeographic analysis. Furthermore, 16 potential recombination events among different sub-genotypes in GI and one in GII were identified, but none of which is inter-genotypic between GI and GII. Overall, the results provide a whole picture of the genetic relatedness of avihepadnavirus strains, which may assist in the surveillance of virus spreading.

Novel intertypic recombination of Echovirus 11 in the Enterovirus species B.

Enteroviruses (EVs), single-stranded, positive-sense RNA viruses, can be classified into four species (A-D), which have previously been linked to a diverse range of disease manifestations and infections affecting the central nervous system. In the Enterovirus species B (EV-B), Echovirus type 11 (E11) has been observed to occasionally circulate in Taiwan, which was responsible for an epidemic of enterovirus infections in 2018. Here, 48 clinical specimens isolated in 2003, 2004, 2009, and 2018 were collected for the high-throughput sequencing. Notably, we identified 2018 Taiwanese strains having potential recombinations in the 3D gene, as well as one 2003 strain having a double recombination with E6 and Coxsackievirus B5 in the P2 and P3 regions, respectively. Additionally, one amino acid signature mutated from the Histidine (H) in throat swab specimens to the Tyrosine (Y) in cerebral spinal fluid specimens was detected at position 1496 (or 57) of the genomic coordinate (or 3A gene) to further demonstrate intra-host evolution in different organs. In conclusion, this study identifies potential intertypic recombination events and an intra-host signature mutation in E11 strains, isolated during a 2018 neurological disease outbreak in Taiwan, contributing to our understanding of its evolution and pathogenesis.

Sink-traps are a major source for carbapenemase-producing Enterobacteriaceae transmission.

We studied the extent of carbapenemase-producing Enterobacteriaceae (CPE) sink contamination and transmission to patients in a nonoutbreak setting. During 2017-2019, 592 patient-room sinks were sampled in 34 departments. Patient weekly rectal swab CPE surveillance was universally performed. Repeated sink sampling was conducted in 9 departments. Isolates from patients and sinks were characterized using pulsed-field gel electrophoresis (PFGE), and pairs of high resemblance were sequenced by Oxford Nanopore and Illumina. Hybrid assembly was used to fully assemble plasmids, which are shared between paired isolates. In total, 144 (24%) of 592 CPE-contaminated sinks were detected in 25 of 34 departments. Repeated sampling (n = 7,123) revealed that 52%-100% were contaminated at least once during the sampling period. Persistent contamination for >1 year by a dominant strain was common. During the study period, 318 patients acquired CPE. The most common species were Klebsiella pneumoniae, Escherichia coli, and Enterobacter spp. In 127 (40%) patients, a contaminated sink was the suspected source of CPE acquisition. For 20 cases with an identical sink-patient strain, temporal relation suggested sink-to-patient transmission. Hybrid assembly of specific sink-patient isolates revealed that shared plasmids were structurally identical, and SNP differences between shared pairs, along with signatures for potential recombination events, suggests recent sharing of the plasmids. CPE-contaminated sinks are an important source of transmission to patients. Although traditionally person-to-person transmission has been considered the main route of CPE transmission, these data suggest a change in paradigm that may influence strategies of preventing CPE dissemination.

A recombination-resistant genome for live attenuated and stable PEDV vaccines by engineering the transcriptional regulatory sequences.

Coronaviruses are important pathogens of humans and animals, and vaccine developments against them are imperative. Due to the ability to induce broad and prolonged protective immunity and the convenient administration routes, live attenuated vaccines (LAVs) are promising arms for controlling the deadly coronavirus infections. However, potential recombination events between vaccine and field strains raise a safety concern for LAVs. The porcine epidemic diarrhea virus (PEDV) remodeled TRS (RMT) mutant generated in this study replicated efficiently in both cell culture and in pigs and retained protective immunogenicity against PEDV challenge in pigs. Furthermore, the RMT PEDV was resistant to recombination and genetically stable. Therefore, RMT PEDV can be further optimized as a backbone for the development of safe LAVs.

Phylogeny and Genetic Divergence among Sorghum Mosaic Virus Isolates Infecting Sugarcane.

Sorghum mosaic virus (SrMV, the genus Potyvirus of the family Potyviridae) is a causal agent of common mosaic in sugarcane and poses a threat to the global sugar industry. In this study, a total of 901 sugarcane leaf samples with mosaic symptom were collected from eight provinces in China and were detected via RT-PCR using a primer pair specific to the SrMV coat protein (CP). These leaf samples included 839 samples from modern cultivars (Saccharum spp. hybrids) and 62 samples from chewing cane (S. officinarum). Among these, 632 out of 901 (70.1%) samples were tested positive for SrMV. The incidences of SrMV infection were 72.3% and 40.3% in modern cultivars and chewing cane, respectively. Phylogenetic analysis showed that all tested SrMV isolates were clustered into three clades consisting of six phylogenetic groups based on 306 CP sequences (this study = 265 and GenBank database = 41). A total of 10 SrMV isolates from South America (the United States and Argentina) along with 106 isolates from China were clustered in group D, while the remaining 190 SrMV isolates from Asia (China and Vietnam) were dispersed in five groups. The SrMV isolates in group F were limited to Yunnan province in China, and those in group A were spread over eight provinces. A significant genetic heterogeneity was elucidated in the nucleotide sequence identities of all SrMV CPs, ranging from 69.0% to 100%. A potential recombination event was postulated among SrMV isolates based on CP sequences. All tested SrMV CPs underwent dominant negative selection. Geographical isolation (South America vs. Asia) and host types (modern cultivars vs. chewing cane) are important factors promoting the genetic differentiation of SrMV populations. Overall, this study contributes to the global understanding of the genetic evolution of SrMV and provides a valuable resource for the epidemiology and management of the mosaic in sugarcane.

Molecular characterization and evolution of the resident population of some alfalfa mosaic virus (AMV) isolates in Egypt

BackgroundAlfalfa mosaic virus (AMV) is an important virus affecting many vegetable crops in Egypt. In this study, virus isolates were collected from naturally infected potato, tomato, alfalfa and clover plants that showed suspected symptoms of AMV in different locations of Beheira and Alexandria governorates during the 2019–2020 growing season. The relative incidence of the virus ranged from 11–25% based on visual observations of symptoms and ELISA testing. A total of 41 samples were tested by ELISA using polyclonal antisera for AMV. Four AMV isolates collected from different host plants, named AM1 from potato, AM2 from tomato, AM3 from alfalfa and AM4 from alfalfa, were maintained on Nicotiana glutinosa plants for further characterization of AMV.ResultsElectron micrographs of the purified viral preparation showed spheroidal particles with a diameter of 18 nm and three bacilliform particles with lengths of roughly 55, 68, and 110 nm and diameters identical to those of the spheroidal particles. The CP gene sequence comparisons of four AMV isolates (AM1, AM2, AM3 and AM4) showed the highest nucleotide identity of 99.7% with the Gomchi isolate from South Korea infecting Gomchi (Ligularia fischeri) plants. Phylogenetic analysis showed that the present isolates were grouped together into a distinct separate clade (GPI) along with the Gomchi isolate from South Korea. Similarly, the deduced amino acid sequence comparisons of Egyptian AMV isolates revealed that amino acids Q29, S30, T34, V92 and V175 were conserved among the Egyptian isolates in GPI.ConclusionThe present study found strong evolutionary evidence for the genetic diversity of AMV isolates by the identification of potential recombination events involving parents from GPI and GPII lineages. Additionally, the study found that Egyptian AMV isolates are genetically stable with low nucleotide diversity. Genetic analysis of the AMV population suggested that the AMV populations differ geographically, and AMV CP gene is under mild purifying selection. Furthermore, the study proposed that the Egyptian AMV population had common evolutionary ancestors with the Asian AMV population. Antioxidant enzymes activity was assessed on N. glutinosa plants in response to infection with each AMV isolate studied, and the results revealed that the enzyme activity varied.

Genetic characterization of duck hepatitis B viruses from Anhui Province, China.

Duck hepatitis B virus (DHBV) infection model was frequently used as the experimental model for human hepatitis B virus (HBV) research. In order to decipher the genetic characteristics of DHBVs from Anhui province of China, 120 duck liver tissue samples were collected and subjected to PCR screening, and 28 samples were detected as DHBV positive. Subsequently, five DHBV-positive samples were selected for genome-wide amplification and a comprehensive analysis. Comparative analysis of complete genome sequences using the MegAlign program showed that five strains of DHBVs shared 94.5-96.3% with each other and 93.2-98.7% with other reference strains in GenBank. The phylogenetic analysis showed that all five DHBV strains belonged to the evolutionary branch of "Chinese DHBV" isolates or DHBV-2. Importantly, three potential intra-genotypic recombination events, between strains AAU-6 and Guilin, strains AAU-1 and GD3, and strains AAU-6 and AAU-1, were respectively found using the RDP and SimPlot softwares and considered the first report in avihepadnaviruses. These results not only improve our understanding for molecular prevalence status of DHBV among ducks, but also provide a reference for recombination mechanism of HBV.

Fast inference of genetic recombination rates in biobank scale data.

Although rates of recombination events across the genome (genetic maps) are fundamental to genetic research, the majority of current studies only use one standard map. There is evidence suggesting population differences in genetic maps, and thus estimating population-specific maps, are of interest. Although the recent availability of biobank-scale data offers such opportunities, current methods are not efficient at leveraging very large sample sizes. The most accurate methods are still linkage disequilibrium (LD)-based methods that are only tractable for a few hundred samples. In this work, we propose a fast and memory-efficient method for estimating genetic maps from population genotyping data. Our method, FastRecomb, leverages the efficient positional Burrows-Wheeler transform (PBWT) data structure for counting IBD segment boundaries as potential recombination events. We used PBWT blocks to avoid redundant counting of pairwise matches. Moreover, we used a panel-smoothing technique to reduce the noise from errors and recent mutations. Using simulation, we found that FastRecomb achieves state-of-the-art performance at 10-kb resolution, in terms of correlation coefficients between the estimated map and the ground truth. This is mainly because FastRecomb can effectively take advantage of large panels comprising more than hundreds of thousands of haplotypes. At the same time, other methods lack the efficiency to handle such data. We believe further refinement of FastRecomb would deliver more accurate genetic maps for the genetics community.

Occurrence and molecular characteristics of pedilanthus leaf curl virus complex from the new hosts fenugreek and night jessamine in Pakistan

Leaf samples of fenugreek plants with leaf yellowing and night jessamine plants with leaf curling symptoms were collected from the vicinity of the University of the Punjab, Lahore, Pakistan. Two complete begomovirus isolates (QM1A and QM3A) and three complete alphasatellite isolates (QM1-a1, QM1-a2, and QM3-a1) were isolated from fenugreek plants. While two complete begomovirus isolates (RR1A and RR2A) and defective betasatellites were identified from night jessamine plants. The isolates QM1A, RR1A, and RR2A shared maximum nucleotide sequence identities of 92–92.9% with pedilanthus leaf curl virus (PeLCV; AM948961) reported from soybean in Pakistan, while QM3A shared 94.1% nucleotide sequence identity with PeLCV. According to the current recommended guidelines for begomovirus species and strain demarcation, the isolates QM1A, RR1A, and RR2A are new PeLCV strains, hence named “Fenugreek strain.” The alphasatellites isolates QM1-a1 and QM1-a2 shared maximum nucleotide sequence identities of 98.8–98.9% with ageratum yellow vein India alphasatellite (AgYVIA; HG515071) whereas, the QM3-a1 isolate was 98.9% identical with ageratum enation alphasatellite (AEA; HE599396) reported from cotton in Pakistan. The recombination analysis revealed the presence of potential recombination events in the isolated begomovirus and alphasatellites. Sequence variation dynamics results showed that alphasatellites populations are more divergent than PeLCV populations. The study identified a new natural complex between PeLCV and DNA-satellites in two distinct plant species. Co-inoculation of agro-infectious clones confirmed the infectivity potential of all DNA-components in the model plant N. benthamiana. The findings of this study highlight the ongoing spread of PeLCV, lending credence to recent reports that PeLCV is an emerging threat to crop production in the Indo-Pak subcontinent.

Multiple potential recombination events among Newcastle disease virus genomes in China between 1946 and 2020.

Newcastle Disease Virus (NDV) is a highly adaptable virus with large genetic diversity that has been widely studied for its oncolytic activities and potential as a vector vaccine. This study investigated the molecular characteristics of 517 complete NDV strains collected from 26 provinces across China between 1946-2020. Herein, phylogenetic, phylogeographic network, recombination, and amino acid variability analyses were performed to reveal the evolutionary characteristics of NDV in China. Phylogenetic analysis revealed the existence of two major groups: GI, which comprises a single genotype Ib, and GII group encompassing eight genotypes (I, II, III, VI. VII. VIII, IX and XII). The Ib genotype is found to dominate China (34%), particularly South and East China, followed by VII (24%) and VI (22%). NDV strains from the two identified groups exhibited great dissimilarities at the nucleotide level of phosphoprotein (P), matrix protein (M), fusion protein (F), and haemagglutinin-neuraminidase (HN) genes. Consistently, the phylogeographic network analysis revealed two main Network Clusters linked to a possible ancestral node from Hunan (strain MH289846.1). Importantly, we identified 34 potential recombination events that involved mostly strains from VII and Ib genotypes. A recombinant of genotype XII isolated in 2019 seems to emerge newly in Southern China. Further, the vaccine strains are found to be highly involved in potential recombination. Therefore, since the influence of recombination on NDV virulence cannot be predicted, this report's findings need to be considered for the security of NDV oncolytic application and the safety of NDV live attenuated vaccines.

Biological and Molecular Characterization of Clover Yellow Vein Virus Infecting Trifolium repens in China

White clover (Trifolium repens L.) is an important perennial legume forage and ornamental plant, and is widely distributed and cultivated in the world. Recently, white clover plants showing symptoms of leaf mosaic and redding were observed in Hohhot, Inner Mongolia of China. In this work, flexuous filamentous viral particles of about 700 × 13 nm in size were observed in the symptomatic leaf samples. The infection of clover yellow vein virus (ClYVV) was confirmed by small RNA sequencing and RT-PCR validation. Mechanical inoculation assays showed that this ClYVV isolate (ClYVV-IM) can infect a range of herbaceous species, including Nicotiana benthamiana, N. occidentalis, Chenopodium quinoa, C. amaranticolor, Vicia faba, Vigna unguiculata, and Solanum lycopersicum, causing various symptoms. The complete genome sequence of ClYVV-IM consists of 9565 nt and shared sequence identities, ranging from 83.05% to 96.30%, with those of the other ClYVV isolates published in GenBank. Phylogenetic analyses based on the polyprotein nucleotide and amino acid sequences clustered 15 ClYVV isolates into two groups and ClYVV-IM located in Group I. Two potential recombination events located at 914–2970 nt and 5153–5694 nt were detected in the genome of ClYVV-IM. To our knowledge, this is the first report of occurrence and complete genome of ClYVV infecting white clover in China.

Genetic comparison of transmissible gastroenteritis coronaviruses.

Transmissible gastroenteritis virus (TGEV) is a porcine coronavirus that threatens animal health and remains elusive despite years of research efforts. The systematical analysis of all available full-length genomes of TGEVs (a total of 43) and porcine respiratory coronaviruses PRCVs (a total of 7) showed that TGEVs fell into two independent evolutionary phylogenetic clades, GI and GII. Viruses circulating in China (until 2021) clustered with the traditional or attenuated vaccine strains within the same evolutionary clades (GI). In contrast, viruses latterly isolated in the USA fell into GII clade. The viruses circulating in China have a lower similarity with that isolated latterly in the USA all through the viral genome. In addition, at least four potential genomic recombination events were identified, three of which occurred in GI clade and one in GII clade. TGEVs circulating in China are distinct from the viruses latterly isolated in the USA at either genomic nucleotide or antigenic levels. Genomic recombination serves as a factor driving the expansion of TGEV genomic diversity.

Epidemiology and Molecular Characterizations of Coronavirus from Companion Animals Living in Chengdu, Southwest China

The recent COVID-19 pandemic has once again caught the attention of people on the probable zoonotic transmission from animals to humans, but the role of companion animals in the coronavirus (CoV) epidemiology still remains unknown. The present study was aimed to investigate epidemiology and molecular characterizations of CoVs from companion animals in Chengdu city, Southwest China. 523 clinical samples from 393 animals were collected from one veterinary hospital between 2020 and 2021, and the presence of CoVs was detected by end-point PCR using pan-CoV assay targeting the RdRp gene. Partial and complete S genes were sequenced for further genotyping and genetic diversity analysis. A total of 162 (31.0%, 162/523) samples and 146 (37.2%, 146/393) animals were tested positive for CoVs. The positive rate in rectal swabs was higher than that in eye/nose/mouth swabs and ascitic fluid but was not statistically different between clinically healthy and diseased ones. Genotyping identified twenty-two feline enteric coronavirus (FCoV) I, four canine enteric coronavirus (CECoV) I, fourteen CECoV IIa, and one CECoV IIb, respectively. Eight complete S genes, including one canine respiratory coronavirus (CRCoV) strain, were successfully obtained. FCoV strains (F21071412 and F21061627) were more closely related to CECoV strains than CRCoV, and C21041821-2 showed potential recombination event. In addition, furin cleavage site between S1 and S2 was identified in two strains. The study supplemented epidemiological information and natural gene pool of CoVs from companion animals. Further understanding of other functional units of CoVs is needed, so as to contribute to the prevention and control of emerging infectious diseases.

Characterization of a novel papillomavirus identified from a whale (Delphinapterus leucas) pharyngeal metagenomic library

Here, using viral metagenomic method, a novel whale papillomavirus (temporarily named wPV, GenBank accession number OP856597) was discovered in a whale (Delphinapterus leucas) pharyngeal metagenomic library. The complete genome size of wPV is 7179 bp, with GC content of 54.4% and a nucleotide composition of 23.4% A, 22.3% T, 28.4% G, and 25.9% C. The viral genome has a typical papillomavirus organization pattern, and five ORFs were predicted, including two late genes encoding L1 and L2, and three early genes encoding E1, E2, and E6. Pairwise sequence comparison and phylogenetic analysis based on the L1 gene sequence indicated that wPV may be a novel species within genus Dyodeltapapillomavirus. In addition, the E2 region of wPV was predicted to have a potential recombination event. The discovery of this novel papillomavirus increases our understanding of the viral ecology of marine mammals, providing insights into possible future infectious diseases.

Discovery of novel Mamastroviruses in Bactrian camels and dromedaries reveals complex recombination history.

Virus emergence may occur through interspecies transmission and recombination of viruses coinfecting a host, with potential to pair novel and adaptive gene combinations. Camels are known to harbor diverse ribonucleic acid viruses with zoonotic and epizootic potential. Among them, astroviruses are of particular interest due to their cross-species transmission potential and endemicity in diverse host species, including humans. We conducted a molecular epidemiological survey of astroviruses in dromedaries from Saudi Arabia and Bactrian camels from Inner Mongolia, China. Herein, we deployed a hybrid sequencing approach coupling deep sequencing with rapid amplification of complementary deoxyribonucleic acid ends to characterize two novel Bactrian and eight dromedary camel astroviruses, including both partial and complete genomes. Our reported sequences expand the known diversity of dromedary camel astroviruses, highlighting potential recombination events among the astroviruses of camelids and other host species. In Bactrian camels, we detected partially conserved gene regions bearing resemblance to human astrovirus types 1, 4, and 8 although we were unable to recover complete reading frames from these samples. Continued surveillance of astroviruses in camelids, particularly Bactrian species and associated livestock, is highly recommended to identify patterns of cross-species transmission and to determine any epizootic threats and zoonotic risks posed to humans. Phylogenomic approaches are needed to investigate complex patterns of recombination among the astroviruses and to infer their evolutionary history across diverse host species.

Evolutionary plasticity of zoonotic porcine Deltacoronavirus (PDCoV): genetic characteristics and geographic distribution

The emergence and rapid spread of the acute respiratory syndrome coronavirus-2 have confirmed that animal coronaviruses represent a potential zoonotic source. Porcine deltacoronavirus is a worldwide evolving enteropathogen of swine, detected first in Hong Kong, China, before its global identification. Following the recent detection of PDCoV in humans, we attempted in this report to re-examine the status of PDCoV phylogenetic classification and evolutionary characteristics. A dataset of 166 complete PDCoV genomes was analyzed using the Maximum Likelihood method in IQ-TREE with the best-fitting model GTR + F + I + G4, revealing two major genogroups (GI and GII), with further seven and two sub-genogroups, (GI a-g) and (GII a-b), respectively. PDCoV strains collected in China exhibited the broadest genetic diversity, distributed in all subgenotypes. Thirty-one potential natural recombination events were identified, 19 of which occurred between China strains, and seven involved at least one China strain as a parental sequence. Importantly, we identified a human Haiti PDCoV strain as recombinant, alarming a possible future spillover that could become a critical threat to human health. The similarity and recombination analysis showed that PDCoV spike ORF is highly variable compared to ORFs encoding other structural proteins. Prediction of linear B cell epitopes of the spike glycoprotein and the 3D structural mapping of amino acid variations of two representative strains of GI and GII showed that the receptor-binding domain (RBD) of spike glycoprotein underwent a significant antigenic drift, suggesting its contribution in the genetic diversity and the wider spread of PDCoV.

Genetic analysis of genome sequence characteristics of two lumpy skin disease viruses isolated from China

BackgroundLumpy skin disease (LSD) is an acute or subacute infectious disease caused by lumpy skin disease virus (LSDV) of genus Capripoxvirus. The outbreaks of LSD were confirmed in the Yili area of the Xinjiang autonomous region in August 2019 and the Fujian province in June 2020. We detected LSDV in our daily monitoring work, then isolated, identified and sequenced the virus, and analyzed the whole genome characteristics of the isolated strain.ResultsWhole genome sequencing revealed that the strains isolated were all LSDV and were named as LSDV XJ201901 and LSDV FJ2019. The results showed that the identity based on whole genome sequences between LSDV XJ201901 and LSDV FJ2019 was 100% and the identity based on whole genome sequences between the two isolated strains and the global LSDV strains was 97.28%-99.99%, with the strain LSDV72/PrachuapKhiriKhan/Thailand/2021 (99.99%) having the highest sequence identity. Analysis of potential recombination events revealed that a total of 18 potential recombination events were identified in strains LSDV XJ201901 and LSDV FJ2019. The two strains are a recombination of Neethling vaccine LW 1959 (GeneBank: AF409138.1) with KSGP 0240 (GeneBank: KX683219.1). It was observed that Neethling vaccine LW 1959 (11/18) and KSGP 0240 (10/18) are involved in most of the potential recombination events.ConclusionsThe virus isolate in this study was LSDV and was identified as a vaccine recombinant strain. The most likely potential parent strains of the two strains in this study are Neethling vaccine LW 1959 and KSGP 0240. The strains in this study are very similar to those isolated in East and Southeast Asia since 2019.

Isolation and characterization of a duck reovirus strain from mature ducks in China

In 2018, a disease characterized by splenic hemorrhage and necrosis killed ducks in a duck farm in Guangxi province, China. A duck reovirus strain was isolated from the tissues of the dead ducks by inoculating duck embryos and BHK-21 cells. Electron microscopy of the cultured the isolate showed that the viral particles were nearly round in shape and approximately 70 nm in diameter, and they were designated DRV-GL18. Sequence analysis showed that the GL18 strain viral genome was 23,419 nt in length and had 10 dsRNA segments. Phylogenetic analysis of cDNA amplicons of segments encoding the protein σC which are outer capsid proteins showed that the isolate belongs to the branch of the epidemic strains of duck reovirus. The Recombination Detection Program (RDP) and SimPlot program analyses suggested potential genetic recombination events in the M2 segments. Pathogenicity experiments revealed that GL18 produced severe hemorrhaging in livers and necrosis in the spleen of infected SPF ducklings. A death rate of 50% in the experimental ducklings was calculated during the first 7 d, and the rest of the ducklings were observed to undergo spleen necrosis. These data suggested that GL18 is a duck reovirus isolate with severer pathogenicity, and it could be a candidate for development of vaccine. This is the first reported isolation of duck reovirus from mature ducks.

Molecular evolution of human coronavirus-NL63, -229E, -HKU1 and -OC43 in hospitalized children in China.

Human coronaviruses (HCoVs) HCoV-NL63, HCoV-229E, HCoV-HKU1 and HCoV-OC43 have been circulated in the human population worldwide, and they are associated with a broad range of respiratory diseases with varying severity. However, there are neither effective therapeutic drugs nor licensed vaccines available for the treatment and prevention of infections by the four HCoVs. In this study, we collected nasopharyngeal aspirates of children hospitalized for respiratory tract infection in China during 2014-2018 and conducted next-generation sequencing. Sequences of four HCoVs were then selected for an in-depth analysis. Genome sequences of 2 HCoV-NL63, 8 HCoV-229E, 2 HCoV-HKU1, and 6 HCoV-OC43 were obtained. Based on the full-length S gene, a strong temporal signal was found in HCoV-229E and the molecular evolutionary rate was 6 × 10-4 substitutions/site/year. Based on the maximum-likelihood (ML) phylogenetic tree of complete S gene, we designated H78 as a new sub-genotype C2 of HCoV-HKU1, and the obtained P43 sequence was grouped into the reported novel genotype K of HCoV-OC43 circulating in Guangzhou, China. Based on the complete genome, potential recombination events were found to occur as two phenomena, namely intraspecies and interspecies. Moreover, we observed two amino acid substitutions in the S1 subunit of obtained HCoV-NL63 (G534V) and HCoV-HKU1 (H512R), while residues 534 and 512 are important for the binding of angiotensin-converting enzyme 2 and neutralizing antibodies, respectively. Our findings might provide a clue for the molecular evolution of the four HCoVs and help in the early diagnosis, treatment and prevention of broad-spectrum HCoV infection.