Full-length human immunodeficiency virus type 1 genomes from subtype C-infected seroconverters in India, with evidence of intersubtype recombination

Evolutionary dynamics and codon bias analysis of canine circovirus: Insights into global spread and host adaptability

Circoviruses are relatively new pathogens, and new circoviruses are constantly being discovered, with a growing range of hosts. Recently, canine circovirus (CanineCV) was reported to infect cats and badgers, further broadening its host range. Previous studies on the evolution and dissemination of CanineCV were fragmented. Here, when conducting a metagenomic analysis of shelter dogs, we identified a canine circovirus positivity rate of 32.4% and obtained three new viral strains. Furthermore, we integrated publicly available viral sequences and employed multiple bioinformatic software tools to analyze the evolution, codon usage bias, recombination, origin, spatiotemporal distribution and host adaptability of CanineCV. In this study, CanineCV could be divided into five distinct phylogenetic clades, named as China-I, China-II, Cosmopolitan, EA, and SEA clades. The extensive inter-clade recombination was observed, which plays an important role in viral evolution, while based on existing sequence information, CanineCV most likely originated in Norway from Vulpes vulpes in 1950.7. Notably, CanineCV exhibits greater adaptability to human hosts compared to previously documented hosts, as indicated by host adaptability indices, suggesting that this virus may possess zoonotic potential. In summary, our study elucidates the phylogeography and evolutionary dynamics of CanineCV and underscores the importance of investigating its potential for zoonotic transmission.

Distinct region-specific neutralization profiles of contemporary HIV-1 clade C against best-in-class broadly neutralizing antibodies

While broadly neutralizing antibodies (bnAbs) have been clinically shown to prevent HIV-1 acquisition, their relative effectiveness against regionally relevant HIV-1 forms is not clear. In the present study, we examined the extent of neutralization susceptibility of contemporary HIV-1 Indian clade C at a population level along with a head-to-head comparison with that from South Africa against a panel of clinically relevant best-in-class bnAbs. Env-pseudotyped viruses encoding HIV-1 India clade C env were found to be best neutralized by the V3 glycan-directed bnAbs (10-1074 and BG18) and select CD4 binding site (CD4bs)-directed bnAbs (VRC07, N6, and 1-18); however, they demonstrated significant resistance to V1/V2 apex-directed bnAbs. Interestingly, the magnitude of the neutralization sensitivity differed between contemporary India and South Africa clade C. Neutralization resistance to key bnAbs was observed to be associated with differences in residues on Env that form bnAb contact sites, gp120 loop lengths, and potential N-linked glycans. Notably, the second generation CD4bs bnAbs (VRC07, N6, 1-18) showed neutralization of VRC01- and 3BNC117-resistant viruses but with two- to sevenfold reduced potency compared to the VRC01-sensitive counterparts, likely due to the enrichment of resistance-associated residues observed in loop D. Predictive analysis indicated that the combination of BG18, N6, and PGDM1400 can provide over 95% neutralization coverage of contemporary India clade C at 1 µg/mL (IC80), an observation distinct from that observed with Africa clade C. Our study clearly highlights that both the complementarity of bnAb classes and the regionally relevant HIV-1 forms are important in achieving clinical effectiveness.IMPORTANCEWhile the development of vaccines to prevent HIV infection remains a global priority, their potential effectiveness is limited by the extraordinarily diversified circulating forms of HIV-1. The prospect of best-in-class broadly neutralizing antibodies (bnAbs) as a potential prevention option has been demonstrated in several studies, including the phase 2b Antibody-Mediated Prevention trials; however, to be broadly applicable, bnAbs will need to overcome the substantial variability of HIV env circulating globally, beyond the regions where efficacy trials are conducted. The present study highlights that the region-specific contemporary HIV-1 clade C viruses not only vary in their degree of susceptibility to the best-in-class clinically relevant bnAbs, but also are evolving at a population level to become increasingly resistant to the best-in-class bnAbs. Overall, the outcome of this study highlights the need for periodic assessment of sequence and neutralization profiles of the circulating regionally relevant HIV-1 forms toward prioritizing the bnAb combination suitable for effective intervention.

Norovirus GI.5 [P4]: first report of the rare norovirus recombinant variant in Northeastern Mexico and its global epidemiological context

Norovirus is the primary cause of acute gastroenteritis outbreaks, considerably impacting children under 5 years, followed by older adults and immunocompromised individuals. As an RNA virus, norovirus exhibits high genetic variability, driven by recombination events at the ORF1-ORF2 junction. This study reports the first detection of the rare norovirus GI.5 [P4] variant in Northeastern Mexico, identified in a single positive isolate (MTY0115; GenBank: PQ369661) from a sample group of 386 individuals, with a prevalence of 0.25%. Notably, norovirus GII was not detected. Phylogenetic analysis of the partial RdRp/VP1 region revealed clustering with global GI.5 [P4] sequences, revealing evolutionary relationships with isolates from Asia, Europe, and America. A recombination event was identified at position 5307 (breakpoint based on reference sequences of GI.5 [P5] and GI.4 [P4]) within ORF1, with genetic inheritance from a GI.5 [P5] isolate from Moscow, Russia, and a GI.4 [P4] isolate from France. Typing classification through sequencing of overlapping ORF1 and ORF2 regions is valuable for understanding genomic variations and their epidemiological impact on at-risk and non-risk populations.

Genomic characteristics and epidemic trends of NADC30-like PRRSV in China

BACKGROUND

NADC30-like PRRSV was first identified in China in 2012 and had become the predominant circulating strain since 2016. Currently, the recombination patterns of NADC30-like PRRSV in China exhibit a high degree of complexity, characterized by low whole-genome sequence homology. The genomic features and epidemiological trends of these strains remain to be elucidated.

RESULTS

To evaluate the prevalence of NADC30-like PRRSV in China, this study acquired 30 whole-genome sequences of NADC30-like strains via Next-Generation Sequencing (NGS). These sequences were subsequently integrated with 224 whole-genome sequences from China available in the GenBank database. A comprehensive analysis of the genomic characteristics of contemporary NADC30-like PRRSV strains in China was conducted. Recombinant analysis indicated a yearly increase in the number of NADC30-like strains exhibiting recombination signals, whereas nonrecombinant NADC30-like strains have become nearly extinct. Among the recombination events, those involving L1C and L8E as parental strains are most prevalent. Based on the results of recombination and phylogenetic analyses, this study classified 120 Chinese NADC30-like strains with similar recombination characteristics into groups NADC30-R1 to R12. The intra-group genetic distances of the NADC30-R1 to R12 groups approximately 5.73% (SD ± 1.68), while the inter-group genetic distances between different groups are usually stably greater than 10%. The amino acid alignment of Nsp2 demonstrated that all NADC30-R1 to R12 strains exhibit a discontinuous deletion of 131 amino acids. These classifications do not exhibit consistent pathogenic characteristics within groups, with most NADC30-like PRRSVs showing moderate virulence. Geographical distribution analysis indicated that NADC30 whole-genome sequences in China originated from 19 provinces. Notably, the NADC30-R1 and NADC30-R2 strains are the most widely distributed and abundant, suggesting that these variants have established localized epidemics in specific regions.

CONCLUSION

In summary, the vast majority of NADC30-like strains in our country have undergone recombination, L1C + L8E is the most common recombination mode. The NADC30-like strains in China can be classified into 12 different recombination patterns, NADC30-R1 and NADC30-R2 strains are already showing pandemic trends. These findings provide a critical foundation for future NADC30-like PRRSV prevention and control strategies.

Characterization of an Emerging Recombinant Duck Circovirus in Northern Vietnam, 2023-2024

This study aimed to characterize the duck circovirus circulating in Northern Vietnam based on complete genome sequences. Between 2023 and 2025, 45 pooled tissue samples were collected from nine duck flocks in several provinces in Northern Vietnam. Of the 45 samples tested, 16 (35.56%) were positive for the DuCV genome, as determined using conventional polymerase chain reaction. Nine representative strains were selected for viral genome sequencing. The results indicated that the complete Vietnamese DuCV genomes were from 1992 to 1995 bp in length, and the degree of nucleotide identity shared among them ranged from 96.88% to 99.84%. Phylogenetic analysis of the complete genomes showed that the nine Vietnamese DuCV strains belonged to genotype I, subgenotypes Ia (two strains), Ib (four strains), and Ic (three strains). These viral strains were genetically related to viruses reported in China from 2019 to 2023. Recombination events occurred on the Cap gene sequences of three Vietnamese DuCV strains (Vietnam/VNUA-102/2023, Vietnam/VNUA-225/2023, and Vietnam/VNUA-318/2024). One positive selection was detected on the Rep protein sequence.

Genetic Diversity in the Capsid Protein-Coding Region of HIV-1 Circulating in Benguela, Angola: Implications for Primary Resistance to the Novel Capsid Inhibitor Lenacapavir

In 2023, the HIV-1 pandemic claimed around 630,000 lives worldwide due to AIDS-related complications. Its burden is significantly heavier in Sub-Saharan Africa, where an increased HIV-1 genetic diversity is common, which increases the risk of resistance to antiretroviral (ARV) drugs. This study aims to update the molecular epidemiology of HIV-1 in Angola, focusing specifically on the gag gene, which is often overlooked, and to assess the potential viability of lenacapavir (LEN)-based ARV therapy in the region. A total of 243 blood samples were collected from ARV-naïve, HIV-infected patients at the General Hospital of Benguela, city of Benguela, Angola. The capsid-encoding region of HIV-1 proviral DNA was amplified by PCR and sequenced. Phylogenetic analysis was performed using the maximum likelihood method, and genome recombinant forms were characterised through bootscanning analysis. Primary resistance mutations to LEN were identified using Stanford University's HIVdb algorithm. Among the 80 successfully sequenced samples, 13 different genetic forms/subtypes were identified, with unique recombinant forms (URFs) (37.5%, 30/80) and subtype C (31.25%, 25/80) being the most prevalent. Regarding resistance mutations, none were detected, apart from four polymorphic mutations. These findings reinforce Angola's position as a transitional HIV-1 hotspot between the genetically highly diverse Central Africa and the subtype C-dominated Southern Africa, while also supporting the potential effectiveness of LEN-based regimens for treatment and prevention of HIV-1 infections in the future.

Detection of a New Recombinant Rabbit Hemorrhagic Disease Virus 2 in China and Development of Virus-like Particle-Based Vaccine

Rabbit hemorrhagic disease virus (RHDV) is a very virulent virus of the genus Lagovirus causing severe and fatal hepatitis in the European rabbit (Oryctolagus cuniculus). RHDV has two distinct genotypes: GI.1 (RHDV) and GI.2 (RHDV2). The first RHDV2/GI.2 strain was identified as a recombinant virus between a non-pathogenic (GI.3P) and a pathogenic (GI.2) lagovirus, and the recombination is thought to have been a key mechanism in the emergence and evolution of RHDV2. Here, a new variant of RHDV2 was identified affecting domestic rabbits on Chinese farms, with a mortality rate of 70-80%. Phylogenetic analysis indicated that the nonstructural portion of this newly identified strain's genome clustered with the GI.1a variants. In contrast, the capsid gene shared the highest nucleotide identity of 97.9% with the North American GI.2 strains, suggesting a possible introduction in China of North American strains and recombination with the GI.1a strains circulating in China. We have produced a recombinant vaccine using the first Chinese GI.2 strain, SC2020/0401, by cloning the vp60 gene into a baculovirus expression vector. Virus-like particles (VLPs) were then produced in Sf9 insect cells, and a challenge study was performed. Rabbits immunized with the VLP vaccine survived 7 d after being challenged with the new virus. The results indicate that commercial vaccines are urgently required in China to control the circulation of RHDV2 variants.

Genetic characterization and pathogenicity of two recombinant PRRSV-2 strains from lineages 1, 3, 5, and 8 emerged in China

BACKGROUND

Porcine reproductive and respiratory syndrome virus (PRRSV) is a major economic threat to the global swine industry. Currently, NADC30-like PRRSV has undergone complex recombination with local Chinese strains, which has exacerbated the evolution of PRRSV. Recently, new recombinant PRRSV-2 strains from four lineages (lineages 1, 3, 5, and 8) have emerged in China. However, information on the pathogenicity of the novel isolate in China remains limited. To further our knowledge about the isolate, FJLIUY2017 and PRRSV2/CN/G8/2018 were selected to analyze their pathogenicity for piglets.

METHODS

The PRRSV FJLIUY2017 and PRRSV2/CN/G8/2018 strains were isolated by porcine alveolar macrophages (PAMs) and MARC-145CD163. Complete genomic sequence analyses were conducted using the DNASTAR 7.0 software and the phylogenetic tree was constructed with MEGA 7.0. Recombination events were detected using RDP V4.10 and SIMPLOT software 3.5.1. Five PRRSV-free per group were inoculated with 2 mL (2 × 105 TCID50) of the FJLIUY-2017 and PRRSV2/CN/G8/2018. Clinical signs of disease were recorded daily after challenge. Blood samples were collected from all piglets on days 0, 4, 7, 11, and 14 dpi for analysis of viral load by IFA and PRRSV-specific antibody levels by ELISA kit. Lung gross and microscopic lesions of the inoculated piglets were examined by scoring system for lung lesion.

RESULTS

Full-length genome analysis revealed that FJLIUY2017 and PRRSV2/CN/G8/2018 share 89.2% identity with each other, and in particular, they had a low degree of homology (< 92%) with PRRSV sequences available in GenBank. Phylogenetic and recombination analyses revealed that the two strains were recombinant viruses from lineages 1, 3, 5.1, and 8.7 strains. Animal studies indicated that FJLIUY-2017 resulted in the typical clinical signs of PRRSV, including persistent fever, higher viremia, severe lung lesions, and 20% mortality, whereas PRRSV2/CN/G8/2018 caused moderate clinical symptoms and no mortality during the challenge period. Hyper-immune sera against the major vaccine strains JXA1-R (lineage 8) and Ingelvac PRRS MLV (Lineage 5) failed to neutralize two strains.

CONCLUSIONS

FJLIUY-2017 caused persistent fever, higher viremia, 20% mortality and exhibited higher pathogenicity in piglets compared to PRRSV2/CN/G8/2018. Our results suggest that recombination between different PRRSV-2 lineages can result in the development of PRRSV variants with increased pathogenicity.

The complete genome sequence of quail coronavirus identified in disease surveillance on quail farms in South Korea

Avian carcasses collected from 103 flocks on 14 quail farms in Korea between 2022 and 2023 were diagnosed with viral diseases (22 flocks), bacterial disease (58 flocks), parasitic diseases (28 flocks) and non-infectious diseases (60 flocks). The only viral disease identified was viral enteritis in quails that showed pathological lesions in duodenum and appeared to be caused by quail coronavirus (QcoV) through viral metagenomics and RT-PCR assay. Two complete genomes of QCoV from samples diagnosed as viral enteritis were obtained using amplicon-based whole genome sequencing. The two QcoVs were gammacoronavirus, but were distinct from other avian coronaviruses. The spike genes of QCoV have 86.2 ∼ 87.1 % identity with that of American turkey coronavirus, but other gene sequences of QcoV was found to be similar to those of Korean infectious bronchitis virus. Genetic analysis based on the complete genomic sequences found QCoVs had a genetic structure similar to avian coronaviruses, yet it seems to be a unique pathogen specific to quail. This is the first report about the complete genome and genetic analysis of QCoV and the result of disease surveillance in quail in South Korea.

A Novel Nobecovirus in an Epomophorus wahlbergi Bat from Nairobi, Kenya

Most human emerging infectious diseases are zoonotic, originating in animal hosts prior to spillover to humans. Prioritizing the surveillance of wildlife that overlaps with humans and human activities can increase the likelihood of detecting viruses with a high potential for human infection. Here, we obtained fecal swabs from two fruit bat species-Eidolon helvum (n = 6) and Epomophorus wahlbergi (n = 43) (family Pteropodidae)-in peridomestic habitats in Nairobi, Kenya, and used metagenome sequencing to detect microorganisms. A near-complete genome of a novel virus assigned taxonomically to the Coronaviridae family Betacoronavirus genus and Nobecovirus subclade was characterized from E. wahlbergi. Phylogenetic analysis indicates this unique Nobecovirus clade shares a common ancestor with Eidolon/Rousettus Nobecovirus subclades isolated from Madagascar, Kenya, and Cameroon. Recombination was detected across open reading frames, except the spike protein, in all BOOTSCAN analyses, indicating intra-host coinfection and genetic exchange between genome regions. Although Nobecoviruses are currently bat-specific and are not known to be zoonotic, the propensity of coronaviruses to undergo frequent recombination events and the location of the virus alongside high human and livestock densities in one of East Africa's most rapidly developing cities justifies continued surveillance of animal viruses in high-risk urban landscapes.

Indicators for Increased Likelihood of Epidemic Kaposi Sarcoma Progression after Antiretroviral Therapy Initiation

Kaposi sarcoma (KS) is a common malignancy for people living with HIV (PLWH), despite antiretroviral therapy (ART). Curiously, even with improved CD4+ T-cell counts and low viral loads following ART, some PLWH with KS may still experience KS progression or even death and require adjuvant chemotherapy to manage their KS. The factors associated with persistent or unresponsive KS after ART initiation remain poorly characterized, and biomarkers to identify patients at risk of KS progression are needed, particularly in resource-limited areas where access to chemotherapy is limited. Here we analyzed baseline KS tumor biopsies from PLWH with KS who required chemotherapy due to unresolved KS after ART initiation and those who did not require chemotherapy after ART initiation. By examining participant metadata and viral copy number for Kaposi sarcoma-associated herpesvirus (KSHV), HIV, cytomegalovirus, and Epstein-Barr virus and KSHV gene expression in the tumor biopsies prior to ART initiation, we identified a model of factors associated with KS progression after ART initiation, including biological sex, age, and the log ratio of KSHV/HIV copy number in the tumor. We believe that the ratio of KSHV/HIV may be linked to the cell types that each virus infects, and future work exploring the relationship between tumor and immune cells in the baseline tumors is planned. Innovation would be necessary to reduce costs and simplify the viral quantification assays, enabling the translation of these findings into routine clinical care, particularly in resource-limited settings.

Some novel field isolates belonging to lineage-1 of the genotype GI-avian infectious bronchitis virus (AIBV) show strong evidence of recombination with field/vaccinal strains

Avian infectious bronchitis virus (AIBV) infection remains one of the significant challenges for the poultry industry due to the high rates of morbidity, mortality, and poor production performance. The AIBV genome is prone to frequent changes due to the possibility of drift and recombination between various genotypes. Despite the massive administration of several types of vaccines, many outbreaks of AIBV continue to be reported worldwide. One of the major goals of this study was to monitor genetic changes in the viral genomes of some recent field isolates of the AIBV from broiler chickens. To achieve these goals, we tested several pools of tissue specimens (trachea and kidneys) from some suspected AIBV outbreaks in broiler chickens by quantitative real-time PCR (q-RT-PCR). We selected two samples, one from the trachea (IBV-4) and one from the kidney (AIBV-6), for the next-generation sequencing (NGS). The full-length genomes of these two isolates were deposited in the GenBank (Accession Numbers: PQ468962 and PQ468963). The viral genome size of AIBV-4 and AIBV-6 was 27,475 and 27,469 nucleotides in length. AIBV-4 have typical AIBV genome organization (5'UTR, ORF1a, ORF1b, S, 3a, 3b, E, M, 4b, 5a, 5b, N, and 3'UTR), while AIBV-6 lack 5b. These two AIBV isolates belong to sublineage-1 of the genotype GI-1 based on the phylogenetic using the full-length, the S, and the N protein sequences. The S1/S2 cleavage sites show polybasic amino acid sequences (RR-F-RR) as direct evidence of virulence of these isolates. The analysis shows multiple recombination events of these isolates with some natural and vaccine strains. The potential major parent for both AIBV-4 and AIBV-6 was AIBV Beaudette. Active and vigilant monitoring of the AIBV sequences of the currently circulating strains in chickens is highly encouraged to help develop novel vaccines and diagnostic assays that match the field circulating strains.

First Isolation and Characterization of Three Strains of Porcine Sapelovirus in Yunnan Province, China

In order to investigate the causes of swine diarrhea in Yunnan Province, this study was conducted to detect and monitor diarrhea viruses through regular sampling and reverse transcription polymerase chain reaction (RT-PCR). In October 2023, porcine sapelovirus (PSV) was detected in fecal specimens collected from diarrheal pigs in Honghe City, and three strains of PSV were successfully isolated by inoculating them into PK-15 cells; electron microscopy revealed virus particles with diameters of ~32 nm. Next-generation sequencing (NGS) revealed that the PSV isolate genomes ranged from 7480 to 7515 nucleotides in length. Homology analyses indicated that ML-15 and ML-16 showed the highest nucleotide and amino acid identities with the Asian PSV strains, ML-19 showed the highest sequence identities with the Zambia PSV strains, and the VP1 to VP4 genes of the three PSV isolates were in the hypervariable region. Phylogenetic analyses showed that the three PSVs isolated in this study all clustered together with Chinese PSV strains; furthermore, recombination analyses indicated that PSV-ML-19 might be a recombined strain and may have emerged through genetic recombination between the major putative parent strain PSV-21-V and the minor putative parent GER L00798-K11 14-02. This was the first reported instance of the isolation and phylogenetic analyses of the PSV strains in Yunnan Province, which enriched the understanding of Chinese PSV strains and indicated the need to prevent and control PSV; the mutation of the VP1 and 3D genes may also provide an important reference for the development of PSV vaccines.

Identification of a potential interspecies reassortant rotavirus G and avastrovirus 2 co-infection from black-headed gull (Chroicocephalus ridibundus) in Hungary

The black-headed gull is the most common nesting gull species in Hungary. Based on the lifestyle and feeding habits of the black-headed gull, which is highly adapted to the human environment, they can be carriers and spreaders of potential human and other animal pathogens. Between 2014 and 2018 within the framework of the "Life Bird Ringing program" a total of 7 faecal samples were collected from gulls and one sample (MR04) was randomly selected for viral metagenomics and mass sequencing. 95.4% and 4% of the reads were classified into family Seadornaviridae and Astroviridae, respectively, and then were verified by RT-PCR method. In this study, the complete genome of a potential interspecies reassortant rotavirus (RV) strain gull/MR04_RV/HUN/2014 (PP239049-PP239059) and the partial ORF1ab, complete ORF2 of a novel avian nephritis virus strain gull/MR04_AAstV/HUN/2014 (PP239060) was discussed. The strain gull/MR04_RV/HUN/2014 was closely related to rotavirus G (RVG) viruses based on the proteins VP1-VP3, VP6, NSP2, NSP3, and NSP5, but it was more related to the human rotavirus B (RVB) strain Bang373 based on the NSP1, NSP4 and VP7, VP4 proteins, which is assumed to be the result of reassortment between different RVG-RVB rotavirus species. The strain gull/MR04_AAstV/HUN/2014 belonged to the genus Avastrovirus species avastrovirus 2 (AAstV-2) and is related to members of group 6 of avian nephritis viruses (ANVs), but based on the genetic distances it may be the first representative of a separate group. Additional gull samples were found to be negative by RT-PCR. Gulls, which are well adapted to the human environment, could potentially spread enterically transmitted viral pathogens like interspecies reassortant rotaviruses (RVG/RVB), but further molecular surveillance is needed to explore more deeply the viral communities of gulls or other related species adapted to human environments.

Surveillance and Genomic Evolution of Infectious Precocity Virus (IPV) from 2011 to 2024

Infectious precocity virus (IPV) poses a significant economic threat to the aquaculture industry by causing sexual precocity and slow growth in Macrobrachium rosenbergii. In this study, we conducted an in-depth investigation into the genetic evolution of IPV from 2011 to 2024 by collecting 31 IPV variants through epidemiological surveys and public databases, including 29 variants with complete genomic sequences. The phylogenetic analysis revealed that these complete genomic sequences clustered into two distinct phylogenetic clades as follows: the Southeast Asian clade and the Chinese clade. Nucleotide and protein variation analyses demonstrated a high degree of similarity, with nucleotide identity ranging from 98.5% to 100% and protein identity from 99.4% to 100%. Further analysis of protein variations within the putative coding region identified two distinct variation patterns. The average dN/dS ratio of 0.12 highlights the strong purifying selection acting on IPV, particularly on structural proteins. In conclusion, this study significantly expands the genomic database of IPV and provides valuable insights into its genetic evolution. These findings offer critical scientific evidence to enhance detection protocols and support sustainable M. rosenbergii aquaculture practices.

The pattern change of hepatitis B virus genetic diversity in Northwestern Tanzania

Hepatitis B virus genetic diversity (HBV) evaluation is scarcely done in Tanzania, imposing a crucial knowledge gap toward elimination of HBV infection by 2030. This cross-sectional study was conducted on purposively selected 21 plasma samples with high HBV-deoxyribonucleic acid (DNA) levels of > 300,000IU/mL. DNA extraction was done using Qiagen DNA Blood Mini Kit (Qiagen, Hilden, Germany). Partial amplification of 423 bp of pol gene, sequencing and analysis; and statistical analysis by STATA version 15 were done. These patients had mean age of 41 ± 11 years with HBV-DNA median of 979 [185.5-8457.5] IU/mL. The genotypes detected were HBV/A; 76.2% (16/21), HBV/D; 19% (4/21), and lastly HBV/G; 4.8% (1/21). Most of the HBV/As and all of the HBV/Ds identified in this study did not cluster with HBV/As and HBV/Ds from other parts of the world. Overall, 19% (4/21) of the patients had HBV escape mutations (T123V, Y134N, P120T and T123A). In conclusion, HBV/A and HBV/D are predominant over time in North-western Tanzania. Most HBV/A and all HBV/D are unique to Tanzania as had been previously reported. However, the pattern of hepatitis B virus genetic diversity is changing in Northwestern Tanzania with occurrence of HBV/G as new genotype in the region.

Uncovering the Prevalence and Genetic Characterization of Rabbit-Derived Paslahepevirus Balayani (Hepatitis E Virus) in Hebei Province, China

Paslahepevirus balayani (hepatitis E virus) is a zoonotic pathogen, with rabbit Paslahepevirus balayani (HEV-3ra) being widely distributed among global rabbit populations. Notably, in China, rabbits constitute a significant HEV host, second only to swine. Emerging evidence suggests that HEV-3ra possesses the capability to cross species barriers and infect humans. Against this backdrop, our investigation aimed to delineate the HEV infection status and epidemiological patterns in the commercial rabbits of Hebei Province, China. We collected 386 liver and 100 fecal samples across four regions in Hebei Province. Detection of HEV RNA in these specimens was achieved by employing reverse transcription quantitative polymerase chain reaction (RT-qPCR) and reverse transcription nested PCR (RT-Nested PCR), focusing on the amplification of a segment of the open reading frame 2 (ORF2) and the complete genome. Among the 486 samples, 73 were tested positive for HEV RNA, resulting in an overall positive rate of 15.0%. The positive rates for liver and fecal samples were 11.7% (45/386) and 28.0% (28/100), respectively. The study successfully obtained 38 partial ORF2 sequences and 5 complete genome sequences. Sequence analysis revealed that the complete genome sequences shared 86.0-94.5% nucleotide identity with HEV-3ra sequences in GenBank. Phylogenetic analysis confirmed that all strains belonged to HEV-3ra and were closely related to previously reported sequences from China. This study provides the first comprehensive genomic overview of circulating HEV-3ra strains in Hebei, offering valuable insights into the infection dynamics and prevalence of HEV-3ra among commercial rabbits, which can inform public health strategies.

Refining genetic classification of global porcine reproductive and respiratory syndrome virus type 1 (PRRSV-1) and investigating their geographic and temporal distributions

Porcine reproductive and respiratory syndrome virus type 1 (PRRSV-1) primarily circulates in Europe but is also detected in North America and Asia. Based on ORF5 sequences, previous studies classified PRRSV-1 into four subtypes. Subtype 1 was further classified into 12 clades (A-L) or into three lineages with lineage 1 including clades 1A-1G and lineage 3 including clades 3A-3G, but the systems are inconsistent and have not been adopted. In this study, we proposed a statistically supported PRRSV-1 genetic classification system based on 10,446 global PRRSV-1 ORF5 sequences spanning 1991-2023. We replaced the colloquial "subtype" designation with "lineage" to reflect evolutionary history and, subsequently, PRRSV-1 was classified into four lineages (L1-L4) with L1 including 18 sublineages (L1.1 to L1.18). The proposed classification system is flexible and may be amended if additional lineages, sublineages, or more granular classifications are needed to reflect contemporary PRRSV-1 detections and evolution. Geographic distributions of PRRSV-1 at lineage and sublineage levels were distinct, with L1 globally distributed and L2, L3 and L4 more restricted. Temporal dynamic changes in some countries were quantified. Classification and ORF5 nucleotide identity of six commercial PRRSV-1 vaccines to each lineage and sublineage and detection frequency of vaccine-like viruses were determined. The phylogenies based on whole-genome and ORF5 sequences demonstrated slightly different tree topologies. Recombination of PRRSV-1 was observed at within-sublineage and between-sublineage levels. A set of ORF5 reference sequences representing the refined classification is available for future diagnostic and epidemiological applications. This study provides a benchmark delineating the current genetic diversity of PRRSV-1 and introduces a refined classification system to support the global standardization and application of ORF5-based genetic classification for PRRSV-1.

Metatranscriptomic identification of novel RNA viruses from raccoon dog (Nyctereutes procyonoides) feces in Japan

The raccoon dog (Nyctereutes procyonoides), classified in the order Carnivora within the family Canidae, is native to East Asia and widely distributed throughout Japan due to its adaptability to various environments. Despite the close relationship between raccoon dogs and other animals, viruses infecting raccoon dogs have not been thoroughly investigated in Japan. In this study, we performed metatranscriptomic analyses using fecal samples collected from latrines of wild raccoon dogs in two locations on mainland Japan. Nearly complete viral genomes were identified, including viruses belonging to the genus Kobuvirus (CaKoV), an unclassified canine sapelovirus within the subfamily Ensavirinae (CaSaV), the Genius Mamastrovirus (CaAstV), unclassified hepe-astro-like virus (bastrovirus-like) (Bast-like V), and an unclassified dicistrovirus (DiciV) within the family Dicistroviridae. Phylogenetic analyses revealed that raccoon dog CaKoV, CaSaV, and CaAstV are related to canine strains but form independent clusters specific to raccoon dogs, suggesting they have evolved within this host population. Bast-like V, detected for the first time in raccoon dogs, showed high sequence identity with viruses previously identified in Chinese shrews. The shared insectivorous nature of these hosts and in silico host range predictions suggest that Bast-like Vs may originate from arthropod viruses. Although DiciV is likely of dietary origin due to its arthropod hosts, the large number of sequence reads detected and the phylogenetic clustering of raccoon dog DiciVs with mammalian DiciVs indicate the need to assess their potential infectivity in mammals and the risk of spillover. These findings suggest that raccoon dogs harbor endemic viruses within the canine population and may act as potential vectors for viruses with unknown infectivity in mammals but with spillover risk.

An outbreak of atypical hand, foot and mouth disease associated Coxsackievirus A6 in children from Cape Verde, 2023

BACKGROUND

Rash is a common childhood infection, mainly caused by viruses. Hand, foot, and mouth disease (HFMD), a common viral rash infection, has become one of the most common infectious diseases in Asian countries and caused outbreaks in children and adults worldwide. Following the introduction of enterovirus A71 (EVA71) vaccines, Coxsackievirus A6 (CVA6) has recently emerged. However, the disease is not commonly reported in Africa, where studies are scarce.

METHODS

In the current study, we focused on the HFMD outbreak that occurred in Cape Verde in July 2023 during field investigations around a cluster of patients with rash and fever. Samples collected from patients were tested using Measles and Rubella-specific immunoglobulin M and quantitative reverse transcription PCR (qRT-PCR) of a panel of viruses causing rashes and subjected to genome sequencing followed by phylogenetic analysis.

RESULTS

Eighteen out of the 22 samples were tested positive for CVA6 RNA by real-time RT-PCR, of which two tested also positive for EVA71 and Coxsackievirus A16 (CVA16). Subsequent sequencing revealed that all CVA6 sequences belonged to the D genotype, particularly the D3 sub-genotype recently described in China.

CONCLUSION

Our study uncovers the first-ever reported outbreak of CVA6 associated with atypical HFMD in children from Cape Verde and highlights thus the need to implement an active hospital-based HFMD surveillance in Africa.

PRRSV-1 outbreak in a farrowing farm caused by a vaccine derived strain: a case report

BACKGROUND

The benefits of porcine reproductive and respiratory syndrome (PRRS) modified live virus vaccines (MLV) have been largely proven, however, the safety of these vaccines is questioned since vaccine strains can revert to virulence due to random mutations or recombination events. Reversion to virulence has been previously described for PRRSV-2 MLVs and recently for PRRSV-1 MLV after recombination. This case report describes the introduction of a PRRSV-1 strain derived from a MLV associated with an outbreak of reproductive disorder in a 1000-sow farrow-to-wean farm in France.

CASE PRESENTATION

In January 2023, unusual fever and lethargy in sows, and premature farrowings were reported in a farm that was regularly controlled as PRRS stable, through mass vaccination of the sows. PRRSV-1 was detected by PCR in sows and suckling piglet samples. Sequencing of ORF5, ORF7, and whole genome (WGS) was performed. Time-to-baseline production and total production losses were calculated using statistical process control methods. ORF5 and ORF7 nucleotide sequences indicated that the strain isolated from the clinical samples was differentiable from the DV MLV strain used in the farm (94.1% and 95.9% respectively) but closely related to the VP-046 Bis MLV strain which was never used (99.0% and 99.2% respectively). WGS of the farm PRRSV strain confirmed the high nucleotide identity percentage with the VP-046 Bis MLV strain (98.6%) over the entire genome and no recombination events was detected with MLV strains authorized in France. After different investigations aiming to identify the source of contamination, we were able to detect a closely related strain (99.46% of identity with the case farm strain across the entire genome) in a wean-to-finish farm located 400 m further. It took 17 batches (34 weeks) to recover the baseline production of piglets after implementation of a PRRSV stabilization protocol, which represented a total loss of 812 weaned piglets.

CONCLUSION

This is the first case report of a PRRSV-1 MLV which might have reverted to virulence in France and has caused substantial economic losses.

Whole genome characterization of feline coronaviruses in Thailand: evidence of genetic recombination and mutation M1058L in pathotype switch

Feline coronavirus (FCoV) is a significant pathogen that infects the feline population worldwide. FCoV can cause mild enteric disease and a fatal systemic disease called feline infectious peritonitis (FIP). In this study, a cross-sectional survey of FCoV in domestic cats from small animal hospitals in Thailand was conducted from January to December 2021. Our result showed that out of 238 samples tested for FCoV using 3' UTR-specific RT-PCR, 18.7% (28/150) of asymptomatic cats and 25.5% (12/47) of cats with unknown status tested positive for FCoVs. Additionally, 51.2% (21/41) of cats with suspected FIP were found to be positive for FCoVs. Genotype identification using S gene-specific RT-PCR showed that all FCoV-positive samples (n = 61) were FCoV type I. This study obtained the whole genome sequences (n = 3) and S gene sequences (n = 21) of Thai-FCoVs. Notably, this study is the first to report the whole genome of Thai-FCoV. Phylogenetic analysis indicated that Thai-FCoVs were closely related to FCoVs from China and Europe. Additionally, the Thai-FCoVs exhibited specific amino acid substitutions (M1058L) associated with the pathotype switch. Recombination events were found to mainly occur in the ORF1ab and S gene regions of Thai-FCoVs. This study provides insights into the occurrence, genetic diversity, virulence amino acid mutations, and potential recombination of FCoVs in the domestic cat population in Thailand, contributing to our understanding of FCoV epidemiology.

Genomic surveillance and evolution of Getah virus

Getah virus (GETV), a member of the Alphaviruses, has spread widely and is expanding its host range worldwide, posing a serious threat to public health safety and the farming industry. However, genetic monitoring of GETV is inadequate, and its evolution and transmission remain unclear. This study employed reverse transcription-polymerase chain reaction to screen pig tissue samples for the presence of GETV. Subsequent steps included DNA sequencing, phylogenetic analysis, and selection pressure assessments to elucidate the evolutionary history and transmission patterns of the virus. A total of 1382 samples were examined, with a positivity rate of 4.12% (95% confidence interval: 3.07%-5.17%) from 2022 to 2023. Subsequently, seven GETV strains were isolated and identified. A phylogenetic tree was constructed, which showed that all seven strains belonged to Group III. Phylodynamic analysis revealed that GETV evolved rapidly. Additionally, eight amino acid sites within the GETV E2 protein were identified as being under positive selection. These data provide insight into the epidemiology and evolution of GETV.

A Novel Genotype of Orientia tsutsugamushi in Human Cases of Scrub Typhus from Southeastern India

Scrub typhus is a mite-borne, re-emerging public health problem in India, particularly in Tamil Nadu, South India. More than 40 serotypes of Orientia tsutsugamushi have been documented worldwide. However, the information on the circulation of its molecular sub-types in India is scanty. A retrospective study was conducted among serologically confirmed cases of scrub typhus. DNA isolated from blood was screened by a nested polymerase chain reaction (nPCR) targeting the GroEL and the 56 kDa type-specific antigen (TSA) genes. Out of 59 samples, 14 partial fragments of GroEL and the twelve 56 kDa genes were PCR-amplified and DNA-sequenced. The neighbor-joining (NJ) analysis indicated three distinct phylogenetic clades, including a novel genotype designated as Ot-Thanjavur-Tamil Nadu (Ot-TJTN, 9 nos. 64.3%); Karp-like (4 nos. 28.6%); and Kuroki-Gilliam type (1 no. 7.1%). Also, phylogenetic analysis of twelve 56 kDa variable domains (VDΙ-ΙΙΙ) of TSA gene sequences revealed a distinctive new genotypic cluster of eight samples (66.6%), and the remaining four (33.4%) were Karp-like genotypes. The Simplot analysis for the similarity and event of recombination testing elucidated the existence of the new genotype of the Ot-TJTN cluster, which was undescribed so far, in the Kato and TA716 lineages. The significant findings recommend further studies to understand the ongoing transmission dynamics of different O. tsutsugamushi strains in vector mites, rodent hosts, and humans in this region.

The replication efficacy of NADC34-like porcine reproductive and respiratory syndrome virus 2 is not directly associated with the pathogenicity

NADC34-like porcine reproductive and respiratory syndrome virus 2 (NADC34-like PRRSV-2) is currently a major prevalent strain in Chinese swine industry. Within which, recombination events are frequently detected. Previous studies have shown that the pathogenicity of NADC34-like PRRSV-2 isolates is highly variable. However, the characteristics between NADC34-like PRRSV-2 recombinant and non-recombinant isolates are rarely compared. In this study, two PRRSV-2 strains (BJ1805-2 and SDLY23-1742) were isolated from samples collected at 2018 and 2023 in China. ORF5-based phylogenetic analysis supported that both isolates are clustered with ORF5 RFLP 1-7-4 (NADC34-like) strains. However, genome-based phylogenetic tree showed that BJ1805-2 is still grouped with NADC34-like isolates but SDLY23-1742 is clustered with NADC30-like viruses. Furthermore, fragment comparisons and recombination detections also supported that SDLY23-1742 was recombined from NADC30-like, NADC34-like, and JXA1-like isolates while no recombination event was detected in BJ1805-2. Noticeably, BJ1805-2 had higher replication efficacy than SDLY23-1742 both in PAMs and in piglets. However, SDLY23-1742 caused longer high fever period and more severe histopathological lung lesions than BJ1805-2, indicating that SDLY23-1742 has higher pathogenicity than BJ1805-2. Overall, this study provides the first evidence that the pathogenicity of NADC34-like PRRSV-2 is not directly correlated with viral replication efficacy.

Molecular Evolutionary Analyses of the RNA-Dependent RNA Polymerase (RdRp) Region and VP1 Gene in Sapovirus GI.1 and GI.2

Human sapovirus (HuSaV) is a significant cause of gastroenteritis. This study aims to analyze the evolutionary dynamics of the RNA-dependent RNA polymerase (RdRp) and capsid (VP1) genes of the HuSaV GI.1 and GI.2 genotypes between 1976 and 2020. Using bioinformatics tools such as the Bayesian phylogenetics software BEAST 2 package (v.2.7.6), we constructed time-scale evolutionary trees based on the gene sequences. Most of the recent common ancestors (MRCAs) of the RdRp region and VP1 gene in the present HuSaV GI.1 diverged around 1930 and 1933, respectively. The trees of the HuSaV GI.1 RdRp region and VP1 gene were divided into two clusters. Further, the MRCAs of the RdRp region and VP1 gene in HuSaV GI.2 diverged in 1960 and 1943, respectively. The evolutionary rates were higher for VP1 gene in HuSaV GI.1 than that in HuSaV GI.2, furthermore, were higher in GI.1 Cluster B than GI.1 Cluster A. In addition, a steep increase was observed in the time-scaled genome population size of the HuSaV GI.1 Cluster B. These results indicate that the HuSaV GI.1 Cluster B may be evolving more actively than other genotypes. The conformational B-cell epitopes were predicted with a higher probability in RdRp for GI.1 and in VP1 for GI.2, respectively. These results suggest that the RdRp region and VP1 gene in HuSaV GI.1 and GI.2 evolved uniquely. These findings suggest unique evolutionary patterns in the RdRp region and VP1 gene of HuSaV GI.1 and GI.2, emphasizing the need for a 'One Health' approach to better understand and combat this pathogen.

Host Specificity and Geographic Dispersion Shape Virome Diversity in Rhinolophus Bats

Rhinolophus bats have been identified as natural reservoirs for viruses with global health implications, including severe acute respiratory syndrome-related coronaviruses (SARSr-CoV) and swine acute diarrhoea syndrome-related coronavirus (SADSr-CoV). In this study, we characterised the individual viromes of 603 bats to systematically investigate the diversity, abundance and geographic distribution of viral communities within R. affinis, R. sinicus and 11 other bat species. The massive metatranscriptomic data revealed substantial viral genome resources of 133 vertebrate-infecting viral clusters, which contain occasional cross-species transmission across mammalian orders and especially across bat families. Notably, those viruses included nine clusters closely related to human and/or livestock pathogens, such as SARS-CoVs and SADS-CoVs. The investigation also highlighted distinct features of viral diversity between and within bat colonies, which appear to be influenced by the distinct host population genetics of R. affinis and R. sinicus species. The comparison of SARSr-CoVs further showed varied impact of host specificity along genome-wide diversification and modular viral evolution among Rhinolophus species. Overall, the findings point to a complex interaction between host genetic diversity, and the way viruses spread and structure within natural populations, calling for continued surveillance efforts to understand factors driving viral transmission and emergence in human populations. These results present the underestimated spillover risk of bat viruses, highlighting the importance of enhancing preparedness and surveillance for emerging zoonotic viruses.

Detection of recombinant type of human adenovirus C composed of type 89 and type 5 in Aichi Prefecture, Japan, 2016-2019

Recombinant human adenoviruses (HAdVs) have been reported from many countries, including Japan. We report a recombinant HAdV-C type detected in feces with gastroenteritis infection or throat swabs with upper respiratory tract inflammation of six children in Aichi Prefecture. This type may have been prevalent in the area. Between April 2014 and March 2019, we attempted to detect HAdVs in 9,483 specimens (fecal, throat swab, urine, and conjunctival swab) collected from patients with suspected viral infection. A total of 220 HAdV-C isolates were obtained and serotyped by neutralization test (NT). Of these, 62 HAdV-C strains (HAdV-C1: 15, -C2: 19, -C5: 22, -C6: 6) were genotyped by sequencing for the three regions, penton base, hexon, and fiber regions, respectively. All 62 strains were grouped into the same genotype as serotype for the hexon and fiber region. In contrast, phylogenetic analysis showed 6 of the 22 strains with serotype HAdV-C5 were grouped into HAdV-C89 for the penton base region. This type was detected as a recombinant HAdV causing SARI in China between 2017 and 2021, was found to have been persistently detected in transnational Aichi Prefecture over the same period.

Recombination Between Bubaline Alphaherpesvirus 1 and Bovine Alphaherpesvirus 1 as a Possible Origin of Bovine Alphaherpesvirus 5

Bovine alphaherpesvirus 1 (BoAHV1) is prevalent in cattle throughout the world, whereas bovine alphaherpesvirus 5 (BoAHV5) prevalence seems restricted to some countries in South America, Australia, and other regions, mainly in the Southern Hemisphere. BoAHV5 infections occur where water buffalo (Bubalus bubalis) farming is practiced, often close to cattle (Bos taurus) farms. Bubaline alphaherpesvirus 1 (BuAHV1), a virus whose natural host is believed to be the water buffaloes, usually causes asymptomatic infections in that species. Here, evidence is provided confirming the close relationship between BuAHV1 and BoAHV5. Phylogenetic and recombination analyses were used to reveal the evolutionary relationship between all whole-genome sequences of BoAHV1 (n = 52), BoAHV5 (n = 7), and BuAHV1 (n = 6) available to date. It is proposed here that BoAHV5 most likely resulted from multiple recombination events between a BuAHV1-like ancestor and BoAHV1-like viruses. The BoAHV5 whole unique short (US) region and most of the unique long (UL) genomic regions seem to have been derived from a BuAHV1-like parental genome, whereas at least six small segments of the UL (corresponding to nucleotides 8287 to 8624; 10,658 to 14,496; 48,013 to 48,269; 71,379 to 71,927; 81,426 to 85,003; and 94,012 to 96,841 of the BoAHV5 genome) and two small segments of the US (corresponding to nucleotides 107,039 to 107,581 and 131,267 to 131,810) have been derived from a BoAHV1-like parental genome. The hypothesis that the BoAHV5 species may have originated following a series of recombination events between BuAHV1 and BoAHV1 variants is consistent with the geographical distribution of BoAHV5, which seems to be prevalent in the regions where cattle and water buffalo farming overlap.

Evolutionary Patterns and Genotype-Specific Amino Acid Mutations of Tick-Borne Encephalitis Virus

Tick-borne encephalitis virus (TBEV) is a significant tick-borne flavivirus responsible for severe human diseases. Here, we analyzed the genetic diversity and evolutionary dynamics of TBEV using 263 genome sequences from the NCBI database and identified key amino acid mutations. TBEV sequences were classified into five genotypes-Baikalian, European, Far-Eastern, Himalaya, and Siberian-showing ORF nucleotide similarity of 81.5% to 88.0% and amino acid similarity of 93.0% to 96.4%. Extensive recombination between genotypes was not observed. Entropy analyses revealed highly variable sites distributed across the Baikalian (n = 2), European (n = 3), Far-Eastern (n = 5), and Siberian (n = 13) genotypes. Each genotype exhibited specific amino acid mutations. Positive selection analysis identified sites under selection in the full dataset (n = 2), as well as in the European (n = 6), Far-Eastern (n = 7), and Siberian (n = 4) genotypes. By integrating highly variable sites, shared genotype-specific mutations, and positively selected sites, we identified 37 key amino acid positions, primarily located on the surfaces of viral proteins. These positions may have a potential impact on protein function and pathogenicity, though further studies are required to validate and evaluate these effects comprehensively. This study provides the first comprehensive analysis of mutational landscapes across TBEV genotypes, uncovering potential critical mutations that may shape viral biology and pathogenicity, and offers valuable insights for further exploration of TBEV characteristics.

The origin and transmission of HIV-1 CRF80_0107 among two major first-tier cities in China

BACKGROUND

CRF01_AE and CRF07_BC are the two most prevalent HIV-1 genotypes in China, and the co-circulation of these two genotypes has led to the continuous generation of CRF_0107 viruses in recent years. However, little is known about the origin and spread of CRF_0107 viruses thus far. This study focused on HIV-1 CRF80_0107, which we previously identified among the MSM population in Beijing and Hebei Province, to explore the demographic distribution, transmission links, and temporal-spatial evolutionary features of the HIV-1 CRF80_0107 strain in China.

METHODS

With the partial pol region fragment of the HIV-1 CRF80_0107 subtype standard sequence as a reference, BLAST was used to search for highly similar sequences in the Los Alamos HIV Sequence Database, followed by preliminary subtype identification via COMET. Further phylogenetic and recombination breakpoint analyses were conducted to verify the subtypes and recombination patterns. We also performed a distance-based molecular network analysis to identify potential relationships among different HIV-positive individuals. In addition, spatiotemporal evolutionary dynamics analysis of the candidate CRF80_0107 sequences was performed via a Bayesian approach.

RESULTS

A total of 36 partial pol gene sequences of HIV-1 CRF80_0107 were identified from 2009 to 2018 from 5 provinces in China. Phylogenetic and spatial-temporal dynamics analyses indicated that CRF80_0107 likely originated in Beijing around 2009 and spread to Guangdong Province around 2012. Population dynamics analysis revealed that CRF80_0107 experienced a significant increase in population size from 2009 to 2011 and then stabilized. The study also found that the number of cases in Guangdong Province was second only to that in Beijing and formed 2 relatively independent transmission clusters in the MSM population in Shenzhen, Guangdong Province.

CONCLUSIONS

The HIV-1 CRF80_0107 strain has spread to cities beyond its origin, particularly the MSM population in Shenzhen city, Guangdong Province, which is an area with a high incidence of HIV. This highlights the importance of continuous monitoring for the emergence and dynamic changes of novel HIV-1 recombinant viruses and the necessity of implementing effective preventive measures targeting specific populations in particular regions.

Identification of novel rodent and shrew orthohepeviruses sheds light on hepatitis E virus evolution

The family Hepeviridae has seen an explosive expansion in its host range in recent years, yet the evolutionary trajectory of this zoonotic pathogen remains largely unknown. The emergence of rat hepatitis E virus (HEV) has introduced a new public health threat due to its potential for zoonotic transmission. This study investigated 2 464 wild small mammals spanning four animal orders, eight families, 21 genera, and 37 species in Yunnan Province, China. Using broadly reactive reverse transcription-polymerase chain reaction (RT-PCR), we systematically screened the presence and prevalence of Orthohepevirus and identified 192 positive specimens from 10 species, corresponding to an overall detection rate of 7.79%. Next-generation sequencing enabled the recovery of 24 full-length genomic sequences from eight host species, including Bandicota bengalensis, Eothenomys eleusis, and Episoriculus caudatus, representing newly reported host species for Orthohepevirus strains. Phylogenetic and sequence analyses revealed extensive genetic diversity within orthohepeviruses infecting rodents and shrews. Notably, among the identified strains, 20 were classified as Rocahepevirus ratti C1, two as C3, and one as Rocahepevirus eothenomi, while the remaining strain exhibited significant divergence, precluding classification. Evolutionary analyses highlighted close associations between orthohepeviruses and their respective host taxa, with distinct phylogenetic clustering patterns observed across different host orders. These findings emphasize the critical roles of co-speciation and cross-species transmission in shaping the evolutionary trajectories of the genera Paslahepevirus and Rocahepevirus.

Molecular and ultrastructural characteristics of virulent and attenuated vaccine strains of goose parvovirus LIV-22

The disease caused by goose parvovirus (GPV) affects young goslings and ducks and leads to substantial losses for farmers due to high mortality rates, reaching 70-100% in naive flocks. Here, we present the results of a study focusing on the historical virulent GPV LIV-22 strain, which was isolated in the USSR in 1972. An attenuated GPV LIV-22 vaccine strain that was generated by continuous passaging in goose embryonic fibroblasts was also studied. Phylogenetic analysis placed both GPV LIV-22 strains in the classical GPV group, close to the vaccine and low-pathogenic strains. However, several individual changes in the GPV LIV-22 VP1 gene highlight the uniqueness of the evolution and adaptation mechanism of GPV LIV-22 strains. Transmission electron microscopy (TEM) revealed severe ultrastructural changes in goose hepatocytes and enterocytes as early as 24-48 h postinfection, confirming abrupt GPV pathogenesis. This description of some of the essential characteristics of the GPV LIV-22 virulent and vaccine strain will be useful for studying GPV evolution and molecular pathogenesis.

Comparative genomics and evolutionary analysis of dengue virus strains circulating in Pakistan

Dengue fever virus (DENV) poses a significant public health risk in tropical and subtropical regions across the world. Although the dengue fever virus (DENV) exhibits significant genetic diversity and has the potential to evolve, there is a lack of comprehensive research on the comparative genomics and evolutionary dynamics of the virus in Pakistan. Phylogenetic analysis demonstrated the circulation of all four dengue virus serotypes (DENV-1, - 2, - 3, and - 4) with prevalent genotypes III and V within DENV-1, cosmopolitan genotype within DENV-2, genotype III within DENV-3, and genotype I within DENV-4 during 2006-2014. Based on the complete envelope region, genome-wide residue signature and genetic diversity indicate that there is a high level of genetic diversity among DENV-1 strains, while DENV-3 strains exhibit the least genetic diversity. Comparative analysis of all four DENV serotypes revealed that certain codons in DENV-2 and -4 were subject to strong purifying selection, while a few codon sites in the envelope region showed evidence of positive selection. These findings provided valuable insights into the comparative genomics and evolutionary pattern of DENV strains reported from Pakistan. Whether those characteristics conferred a fitness advantage to DENV-1 genotypes within a specific geography and time interval warrants further investigations. The findings of the current study will contribute to tracking disease dynamics, understanding virus transmission and evolution, and formulating effective disease control strategies.

Molecular Epidemiology, Transmission, and Evolution of Rubella Virus Circulating in Tianjin, China, Between 2009 and 2020

Rubella is listed as a disease that needs to be eliminated worldwide by the World Health Organization. This study aimed to investigate rubella epidemiology and genetic characteristics based on data from 12 years of laboratory-based surveillance (2009-2020) in Tianjin and to provide baseline genotype data for monitoring future rubella control efforts. We collected RV-positive throat swab samples from confirmed rubella cases during 2009-2020 in Tianjin to isolate RV, amplify and sequence target gene fragments, construct phylogenetic trees, and analyze nucleotide homologies. Four rubella isolates were chosen for whole genome sequencing. The epidemiological data of rubella cases were collected to describe and analyze the epidemiological characteristics of the rubella outbreak. Most cases (87.6%) occurred between March and June, and the peak incidence was observed in May. The age of the reported rubella cases ranged from almost 1 month to 82 years, most were between 10 and 29 years old (83.3%). Almost half (48.3%) of the confirmed rubella cases were from just four districts (Beichen District, Binhai New Area, Hebei District, and Nankai District). A total of 211 rubella virus strains were obtained during 2009-2020, phylogenetic analyses identified four lineages, including 1E-L1, 1E-L2, 2B-L1, and 2B-L2c, with high homologies of nucleotide sequences compared with RV strains from other provinces of China. Recombination analysis indicated that strain RVi/Tianjin.CHN/37.19/1 a possible recombination strain by 7 analysis methods, with p-values of 4.993 × 10-28-2.922 × 10-4. Our study provided comprehensive data on rubella epidemiology and the first information on rubella genotypes in Tianjin. Clear evidence of recombination was found, indicating that RV has the potential to continually mutate, so close monitoring of the genetic variations of wild-type rubella virus strains is necessary. Rubella viruses were highly conserved at the genomic level, the incidence of rubella in Tianjin, as well as in China, has sustains at a low level, which gives us the idea that the rubella control and elimination goal could be achieved in the near future if strengthened RV surveillance continues and vaccine immunization coverage maintaining at the high level.

Sequence Notes: Near Full-Length Genome Analysis of the First-Reported HIV-1 Circulating Recombinant Form (CRF)_10CD in Uganda

HIV-1 is characterized by remarkable genetic diversity resulting from its high replication rate, error-prone reverse transcriptase enzyme and recombination events. In Uganda, HIV-1 subtype diversity is mostly dominated by subtypes A, D, and A1/D Unique Recombinant Forms (URFs). In this study, deep sequences of HIV from patients with known antiretroviral therapy (ART) status were analyzed to determine the subtypes and to identify drug-resistance mutations circulating in the study population. Of the 187 participant samples processed for next-generation sequencing (NGS), 137 (73%) were successfully classified. The majority of HIV-1 strains were classified as subtype A (75, 55%), D (43, 31%), with other subtypes including C (3, 2%), A1/D (9, 7%) and CRF10_CD (1, <1%). Recombinant analysis of nine complete A1/D HIV genomes identified novel recombination patterns described herein. Furthermore, we report for the first time in Uganda, an HIV-1 CRF10_CD strain from a fisherfolk in a Lake Victoria Island fishing community.

Isolation and characterization of a novel S-gene mutation porcine deltacoronavirus with high pathogenicity from diarrhea piglet in Zhejiang Province, China, 2022

Porcine deltacoronavirus (PDCoV) is a coronavirus that causes diarrhea in suckling piglets and has the potential for cross-species transmission. Monitoring PDCoV evolution and identifying potential vaccine candidates are crucial due to its high mutation rates in pig populations. In this study, a Chinese PDCoV strain named ZD2022 was successfully isolated from diarrhea piglets in Zhejiang province, followed by genetic evolutionary analysis, assessment of S proteins' biological functions, in vitro cellular adaptation analysis and pathogenicity evaluation. Phylogenetic analyses placed the PDCoV ZD2022 strain within the Southeast Asia Lineage. Sequence analysis revealed 23 mutations in the S protein of ZD2022 compared to most of other Chinese PDCoV strains, including 8 unique mutations (T529I, L579F, Q614H, V709G, S959L, P1010S, V1016F, A1068V). In addition, bioinformatic predictions indicated these mutations impact the hydrophilicity/hydrophobicity, antigenic epitopes and N-glycosylation sites of the ZD2022 S protein. The virus growth curve of ZD2022 showed good cellular adaptation, with peak viral titers of 8.92 ± 0.31 Log10 TCID50/mL in ST cells. Furthermore, ZD2022 exhibited high virulence in suckling piglets, causing severe diarrhea in piglets at 60 h post-inoculation (hpi) and a mortality rate of 40 % (2/5) within 96 hpi. In summary, our findings indicate that the Chinese PDCoV strains continue to mutate, and the novel S gene mutation in strain ZD2022 offers strong cellular adaptation and high pathogenicity, making it a potential candidate strain for vaccine development.

Full genome sequence analysis of the predominant and uncommon G9P[4] rotavirus strains circulating in Tehran, Iran, 2021-2022: Evidence for inter and intra-genotype recombination

Group A rotaviruses (RVAs) are a major cause of acute gastroenteritis in children under 5 years of age worldwide. Herein, the genetic sequences of 11 RNA segments from three uncommon G9P[4] RVA strains found in the stool samples of children under 5 years of age in Iran were analyzed using next-generation sequencing (NGS) technology. The genomic constellations of these three uncommon G9P[4] strains indicated the presence of the double and quadruple reassortants of two G9P[4] strains, containing the VP7/NSP2 and VP7/VP2/NSP2/NSP4 genes on a DS-1-like genetic background, respectively. The genome of one strain indicated a Wa-like genetic backbone in a single-reassortant with the VP4 of the DS1-like human strains. With the exception of VP1, VP2, VP7, NSP2, NSP3, and NSP4 genes, which clustered with RVA of human origins belonging to cognate gene sequences of genogroup 1/2 genotypes/lineages, the remaining five genes (VP8/VP4, VP3, VP6, NSP1, NSP5) displayed direct evidence of recombination. It is presumed that the presence of uncommon G9P[4] strains in Iran is not linked to vaccination pressure, but rather to the high prevalence of RVA co-infection or the direct import of these uncommon RVA reassortants strains from other countries (especially those that have implemented RV vaccination).

Isolation and characterization of a novel S1-gene insertion porcine epidemic diarrhea virus with low pathogenicity in newborn piglets

Porcine epidemic diarrhea virus (PEDV) causes diarrhea and vomiting in piglets, leading to a mortality rate of 100%. Due to the high frequency of mutation, it is important to monitor the evolution of PEDV and develop potential vaccine candidates. In this study, two PEDV strains (ZJ2022 and ZQ2022) were identified by PCR. These strains were subsequently isolated, and their genome sequences, growth characteristics, and pathogenicity were compared. Phylogenetic and recombination analyses revealed that both strains belonged to GIIa-subgroup, and ZQ2022 was identified as a recombinant strain derived from ZJ2022. Further sequence analysis showed that the ZJ2022 strain had a modified top region of the S1 protein due to a three amino acid insertion (T380_Y380insGGE) in the S1 gene. According to the virus growth curve, ZJ2022 exhibited better cellular adaptation than ZQ2022, with higher viral titers from 8 hpi to 24 hpi. Additionally, ZQ2022 exhibited a high level of pathogenicity, causing severe diarrhea in piglets at 36 hpi and a 100% mortality rate by 96 hpi. In contrast, ZJ2022 showed lower pathogenicity, inducing severe diarrhea in piglets at 60 hpi, with a mortality rate of 60% at 96 hpi and 100% at 120 hpi. In summary, our findings provided evidence of the undergoing mutations in Chinese PEDV strains. Furthermore, the S gene insertion strain ZJ2022 exhibited strong cellular adaptability and low pathogenicity, making it a potential candidate strain for vaccine development.

Five-year longitudinal surveillance reveals the continual circulation of both alpha- and beta-coronaviruses in Plateau and Gansu pikas (Ochotona spp.) at Qinghai Lake, China1

The discovery of alphacoronaviruses and betacoronaviruses in plateau pikas (Ochotona curzoniae) expanded the host range of mammalian coronavirus (CoV) to a new order - Lagomorpha. However, the diversity and evolutionary relationships of CoVs in these plateau-region-specific animal population remains uncertain. We conducted a five-year longitudinal surveillance of CoVs harboured by pikas around Qinghai Lake, China. CoVs were identified in 33 of 236 plateau pikas and 2 of 6 Gansu pikas (Ochotona cansus), with a total positivity rate of 14.5%, and exhibiting a wide spatiotemporal distribution across seven sampling sites and six time points. Through meta-transcriptomic sequencing and RT-PCR, we recovered 16 near-complete viral genome sequences. Phylogenetic analyses classified the viruses as variants of either pika alphacoronaviruses or betacoronaviruses endemic to plateau pikas from the Qinghai-Tibet Plateau region. Of particular note, the pika-associated betacoronaviruses may represent a novel subgenus within the genus Betacoronavirus. Tissue tropism, evaluated using quantitative real-time PCR, revealed the presence of CoV in the rectal and/or lung tissues, with the highest viral loads at 103.55 or 102.80 RNA copies/μL. Surface plasmon resonance (SPR) assays indicated that the newly identified betacoronavirus did not bind to human or pika Angiotensin-converting enzyme 2 (ACE2) or Dipeptidyl peptidase 4 (DPP4). The findings highlight the ongoing circulation and broadening host spectrum of CoVs among pikas, emphasizing the necessity for further investigation to evaluate their potential public health risks.

Genomic tools for post-elimination measles molecular epidemiology using Canadian surveillance data from 2018-2020

Introduction

Measles is caused by the highly infectious measles virus, MeV, for which there is an effective vaccine. Monitoring of progress of measles elimination requires enhanced surveillance and tracking of MeV strains, including documenting the absence of an endemically circulating strain. Due to a reduction in the number of circulating genotypes, additional sequence information, beyond the standardized 450 nucleotide window of the nucleoprotein (N450), is required to corroborate the information from epidemiological investigations and, ideally, fill in gaps in the surveillance data.

Methods

This study applies MeV sequencing tools, namely the N450, the non-coding region between the matrix and fusion genes (MF-NCR), and the complete coding sequence of the genome (WGS-t), to clinical specimens obtained from cases occurring over a three-year time period in Canada. This data was systematically analyzed, including with Bayesian evolutionary analysis by sampling trees (BEAST) of the WGS-t.

Results and discussion

Of the 143 reported cases, N450, MF-NCR, and WGS-t sequences were obtained from 101, 81, and 75 cases, respectively. The BEAST analysis confirmed that the two most frequently detected lineages (B3 named strain MVi/Marikina City.PHL/10.18 and D8 named strain MVs/Gir Somnath.IND/42.16) were the result of repeated importations. Of the 16 outbreaks occurring during the study period, the analysis conclusively corroborated the epidemiological information for 13. BEAST analysis of the WGS-t convincingly demonstrated the expansion of two outbreaks by the inclusion of additional contemporary cases for which the epidemiological investigation had been unable to identify links. Furthermore, the analysis revealed the existence of three additional unrecognized outbreaks among the cases categorized as unknown source. One outbreak was without WGS-t and could not be resolved.

Conclusion

Measles WGS-t data corroborated and expanded upon the outbreak analysis from traditional epidemiological investigations of measles outbreaks. However, both are needed for fulsome investigations in elimination settings.

Identification of Recombinant Aichivirus D in Cattle, Italy

Kobuviruses (KoVs) are a group of small, non-enveloped RNA viruses classified in the genus Kobuvirus within the Picornaviridae family, comprising Aichivirus species A to F. KoVs have been identified in humans and several mammals, including domestic ungulates. This study investigated the presence of KoVs in a collection of bovine stool samples (n = 38) obtained from animals with enteritis or without clinical signs. By RT-PCR screening, KoV RNA was detected in 10/38 animals (26.3%). Six of the ten positive animals had enteric signs. On sequence analysis of the amplicons, eight strains were related to species Aichivirus B, commonly identified in cattle. In contrast, two strains (ITA/2019/572-1 and ITA/2020/bovine/30-2), displayed the highest nt identity (up to 97.1%) to cattle, yak, and goat Aichivirus D strains. On whole genome analysis, strains ITA/2019/572-1 and ITA/2020/30-2 showed 88.9% nt identity to each other and 87.8-90.3% nt to the bovine kobuvirus strain CHN/2021/ON730709 identified in China. Interestingly these three Aichivirus D strains showed a recombinant makeup, clustering with D1 genotype in the capsid region and with D2 genotype in the non-structural genes. These findings suggest that Aichivirus D KoVs are common components of livestock virome. Understanding the genetic diversity of KoVs in animals will be useful to improve the diagnostics and gather epidemiological data.

Recent Molecular Epidemiology of Echovirus 11 Throughout North and West Africa Resulted in the First Identification of a Recombinant Strain from an Acute Flaccid Paralysis Case in West Africa

Echovirus 11 has emerged as a major public health concern, causing sepsis in neonates in many European countries in recent years. In Africa, especially West Africa, where resources and diagnostic capacities are limited, only sporadic cases have been reported. To better understand the recent molecular epidemiology of E11 in West Africa, we characterized twenty-three echovirus 11 strains isolated through the acute flaccid paralysis and environmental surveillance systems for polio from 2013 to 2023, using high-throughput sequencing. Our data are noteworthy due to identifying for the first time a recombinant strain from an acute flaccid paralysis case and represent the first focus to date on molecular characterization of echovirus 11 in West Africa. Moreover, our data show that echovirus 11 diverged from 1970 (95% HPD range, 1961-1979) and evolved into four distinct clades, with the virus spread from West Africa to Europe, exhibiting two introductions in France around 2017, from Senegal and Guinea. Furthermore, the in silico analysis reveals four non-conservative amino acid substitutions in the VP1 sequences of the European strains associated with neonatal sepsis in newborns and a conserved amino acid motif in the VP1 protein toward enterovirus genotypes. Our data provide new insights into the epidemiology of echovirus 11 and point to the crucial need to implement specific surveillance programs targeting non-polio enteroviruses for the rapid identification of emerging or re-emerging enterovirus species, particularly in Africa.

Positive selection, genetic recombination, and intra-host evolution in novel equine coronavirus genomes and other members of the Embecovirus subgenus

There are several examples of coronaviruses in the Betacoronavirus subgenus Embecovirus that have jumped from an animal to the human host. Studying how evolutionary factors shape coronaviruses in non-human hosts may provide insight into the coronavirus host-switching potential. Equids, such as horses and donkeys, are susceptible to equine coronaviruses (ECoVs). With increased testing prevalence, several ECoV genome sequences have become available for molecular evolutionary analyses, especially those from the United States of America (USA). To date, no analyses have been performed to characterize evolution within coding regions of the ECoV genome. Here, we obtain and describe four new ECoV genome sequences from infected equines from across the USA presenting clinical symptoms of ECoV, and infer ECoV-specific and Embecovirus-wide patterns of molecular evolution. Within two of the four data sets analyzed, we find evidence of intra-host evolution within the nucleocapsid (N) gene, suggestive of quasispecies development. We also identify 12 putative genetic recombination events within the ECoV genome, 11 of which fall in ORF1ab. Finally, we infer and compare sites subject to positive selection on the ancestral branch of each major Embecovirus member clade. Specifically, for the two currently identified human coronavirus (HCoV) embecoviruses that have spilled from animals to humans (HCoV-OC43 and HCoV-HKU1), we find that there are 42 and 2 such sites, respectively, perhaps reflective of the more complex ancestral evolutionary history of HCoV-OC43, which involves several different animal hosts.IMPORTANCEThe Betacoronavirus subgenus Embecovirus contains coronaviruses that not only pose a health threat to animals and humans, but also have jumped from animal to human host. Equids, such as horses and donkeys are susceptible to equine coronavirus (ECoV) infections. No studies have systematically examined evolutionary patterns within ECoV genomes. Our study addresses this gap and provides insight into intra-host ECoV evolution from infected horses. Further, we identify and report natural selection pattern differences between two embecoviruses that have jumped from animals to humans [human coronavirus OC43 and HKU1 (HCoV-OC43 and HCoV-HKU1, respectively)], and hypothesize that the differences observed may be due to the different animal host(s) that each virus circulated in prior to its jump into humans. Finally, we contribute four novel, high-quality ECoV genomes to the scientific community.

High HIV-1 genetic diversity and low prevalence of transmitted drug resistance among treatment-naive people living with HIV in Madagascar

BACKGROUND AND OBJECTIVES

Data on HIV drug resistance in Madagascar are rare and outdated. In this study, we assessed the prevalence of HIV drug resistance mutations to antiretrovirals (ARVs) and genetic diversity of circulating strains in treatment-naive people living with HIV (PLHIV) in Madagascar.

MATERIALS AND METHODS

We amplified the protease (PR), fragments of the Reverse Transcriptase (RT) and Integrase (IN) genes according to the French ANRS protocol. The amplicons were sequenced using next-generation sequencing technology on an Illumina platform (MiSeq). We determined HIV-1 subtypes through phylogenetic analysis using maximum likelihood in PhyML. Resistance interpretation was performed using the Stanford algorithm (version 9.5.1).

RESULTS

We included 239 HIV-infected adults and children, sampled between January 2019 and November 2023, with a median age of 30 years and a mean plasma HIV viral load of 6.3 Log copies/mL. We sequenced at least one genomic fragment (PR or RT or IN) of the 239 samples, but 9 were excluded from analysis (mean depth < 10,000×). Phylogenetic analysis of 230 sequences revealed the presence of subtype C (33.91 %), A1 (11.30 %), B (11.30 %), CRF02_AG (9.56 %), subtype G (3.04 %), subtype D (0.43 %), CRF01_AE (0.43 %), and a significant proportion of unique recombinant forms (URFs) (30.30 %). The prevalence of transmitted drug resistance (TDR) was 4.95 % (10/202) among patients aged 15 years and older. When stratified by ARV class, this prevalence was 4.79 % for non-nucleoside reverse transcriptase inhibitors (NNRTIs), 0.59 % for Nucleoside Reverse Transcriptase inhibitors (NRTIs), and 0.50 % for integrase strand transfer inhibitors (INSTIs). Among children under 15 years old (n = 28), the prevalence of TDR was 14.28 % (4/28), with all mutations conferring resistance to NNRTIs. No mutation conferring resistance to protease inhibitors was found, neither in children nor in adults.

CONCLUSION

Our results show a low prevalence of ARV resistance mutations among adult treatment-naive PLHIV in Madagascar. In children under 15 years old, 92 % were infants under two years old, the high resistance rate is likely related to mother-to-child transmission. No resistance mutation to dolutegravir was detected. We also observed high frequencies of subtypes C, B, A1 and a high proportion of URFs, highlighting an ongoing dynamic epidemic.

Multiple Genotypes and Reassortants of Severe Fever With Thrombocytopenia Syndrome Virus Co-Circulating in Hangzhou in Southeastern China, 2013-2023

Severe fever with thrombocytopenia syndrome (SFTS), a tick-borne infectious disease caused by the SFTS virus (SFTSV), is becoming a significant public health threat due to its high mortality rate. Knowledge of SFTSV in southeastern coastal China is limited. The whole genomes of 66 SFTSV strains collected from 2013 to 2023 in Hangzhou, a coastal city in China, were amplified and sequenced to elucidate the geography-related genetic and pathogenic diversity. Hangzhou SFTSVs could be classified into five pure genotype groups (A, B-2, D, E, and F); genotype A was dominant, and genotype E was significantly associated with SFTS fatality. An unclassified sublineage of the L segment was proposed as a novel B-4 subgenotype. Seven types of genetic reassortants (abbreviated as B-3B-3B-1, CCA, B-2AB-2, B-2CB-2, DFD, B-4FF, and B-4B-2B-1 for the L, M, and S segments) were identified, including three novel forms. Six recombination events and ten amino acid substitutions were identified in the Hangzhou viruses. Collectively, our results demonstrated that all known SFTSV genotypes co-circulated in Hangzhou, leading to a gradual increase in genetic diversity and the generation of novel reassortants. Increased surveillance is urgently needed in Hangzhou, a critical region for SFTSV genetic exchange.

Novel Intertypic Recombinant Coxsackievirus A2 Containing Specific Amino Acid Mutations in the RNA-Dependent RNA Polymerase Potentially Associated With Its Emergence

Coxsackievirus A2 (CVA2), a member of enterovirus A species (EV-A), is associated with diverse human diseases and occasionally causes acute gastroenteritis (AGE). In Thailand, CVA2 emerged as the predominant genotype in 2019. The increasing incidence of CVA2, coupled with the limited availability of full-length genomes, highlights the need for more complete genome sequence analysis to facilitate molecular epidemiology study. This study aimed to investigate the molecular epidemiology, evolutionary dynamics, and recombination characteristics of CVA2 associated with AGE in Thailand from 2013 to 2022. A total of 19 full-genome sequences of CVA2 isolated from stool samples of AGE patients in Thailand were characterized and analyzed together with the reference sequences available in the GenBank database. A novel lineage of CVA2 (subgenotype C5) was detected with the potential recombination with CVA10 within the P2 and P3 regions. Specific consensus amino acid mutations, A61S in the VP3 gene and R136K in the 3D (RdRp) gene, were identified in all CVA2 recombinant strains. Additionally, the S45G mutation in the RdRp gene was found to be potentially associated with the emergence of CVA2 infection in 2019. In conclusion, this study reveals potential intertypic recombinant events and specific mutations in CVA2 strains isolated from AGE patients and provides a broader understanding of its evolutionary epidemiology.

Genetic Diversity and Recombination Analysis of Canine Parvoviruses Prevalent in Central and Eastern China, from 2020 to 2023

Canine parvovirus type-2 (CPV-2), the primary causative agent of serious canine enteric diseases, is highly contagious and associated with high fatality rates worldwide. To comprehend the current emergence of CPV-2 in central and eastern China, 130 rectal swabs from domestic or stray dogs with gastroenteritis symptoms were collected during 2020-2023. A total of 118 positive samples were detected via polymerase chain reaction, and further used to amplify and sequence the VP2 gene. Sequence analysis of the deduced amino acids of VP2 protein indicated that CPV-2c was the most prevalent variant (n = 106, 89.83%), followed by the novel CPV-2a (n = 10, 8.47%) and CPV-2b (n = 2, 1.69%) variants. The VP2 protein from the obtained and reference strains showed 86.95% (AH2103 and HB2108) to 99.94% identity. Based on the nine predicted recombination events, some prevalent CPV-2c strains were highly similar to previously isolated strains, indicating their complex evolution and recombination. The predicted analysis suggested that mutations in the antigen epitope (Val219Ile, Phe267Tyr, and Asn426Glu) and other mutations (Met87Leu, Ile101Thr, and Ser297Ala) affect the tertiary structure of the VP2 protein. This research will help us understand the recent evolution and mutation of Chinese CPV-2 and provide suggestions for updating the CPV-2 vaccine.

Phylogenetic Insights into H7Nx Influenza Viruses: Uncovering Reassortment Patterns and Geographic Variability

Influenza A viruses (IAVs), which belong to the Orthomyxoviridae family, are RNA viruses characterized by a segmented genome that allows them to evolve and adapt rapidly. These viruses are mainly transmitted by wild waterfowl. In this study, we investigated the evolutionary processes of H7Nx (H7N1, H7N2, H7N3, H7N4, H7N5, H7N6, H7N7, H7N8, H7N9) viruses, which pose a significant pandemic risk due to the known cases of human infection and their potential for rapid genetic evolution and reassortment. The complete genome sequences of H7Nx influenza viruses (n = 3239) were compared between each other to investigate their phylogenetic relationships and reassortment patterns. For the selected viruses, phylogenetic trees were constructed for eight genome segments (PB2, PB1, PA, HA, NP, NA, M, NS) to assess the genetic diversity and geographic distribution of these viruses. Distinct phylogenetic clades with remarkable geographic patterns were found for the different segments. While the viruses were consistently grouped by subtype based on the NA segment sequences, the phylogeny of the other segment sequences, with the exception of the NS segment, showed distinct grouping patterns based on geographic origin rather than formal subtype assignment. Reassortment events leading to complex phylogenetic relationships were frequently observed. In addition, multiple cases of previously undescribed reassortments between subtypes were detected, emphasizing the fluidity of H7Nx virus populations. These results indicate a high degree of genetic diversity and reassortment within H7Nx influenza viruses. In other words, H7Nx viruses exist as constantly changing combinations of gene pools rather than stable genetic lineages.

Genomic and pathogenicity analysis of two novel highly pathogenic recombinant NADC30-like PRRSV strains in China, in 2023

Porcine reproductive and respiratory syndrome viruses (PRRSVs) exhibit high mutability and recombination, posing challenges to their immunization and control. This study isolated two new PRRSV strains, GD-7 and GX-3, from samples collected in Guangdong and Guangxi in 2023. Whole-genome sequencing, along with phylogenetic and recombination analyses, confirmed that GD-7 and GX-3 are natural novel recombinant strains of NADC30 PRRSV. Moreover, we established a pathogenicity model for piglets and sows based on the two isolates. The results of piglet pathogenicity revealed that both GD-7 and GX-3 caused clinical symptoms such as fever, loss of appetite, depression, and slow weight gain. Moreover, we observed that the mortality rate of GD-7-inoculated group piglets was 33.3%, which was similar to that of piglets infected with other highly pathogenic PRRSV strains and exceeded the mortality rate of most NADC30-like PRRSV. In pregnant sow models, the survival rate of sows in the GD-7 group was 75%, in contrast to the GX-3 group, where no sow mortality was observed, and both strains resulted in abortion, mummified fetuses, and stillbirths. These results highlight the elevated pathogenicity of these recombinant strains in sows, with GD-7 mainly causing sows to abort, and GX-3 mainly causing sows to give birth to mummified fetuses. This study introduces two distinct clinical recombinant PRRSV strains that differ from the prevalent strains in China. This research furthers our understanding of the epidemiology of PRRSV and underscores the significance of ongoing monitoring and research in the face of evolving virus strains. Moreover, these discoveries act as early warnings, underscoring the necessity for active control and immunization against PRRSV.IMPORTANCESince the discovery of NADC30-like PRRSV in China in 2013, it has gradually become the dominant strain of PRRSV in China. NADC30-like PRRSV exhibits high recombination characteristics, constantly recombining with different strains, leading to the emergence of numerous novel strains. Of particular importance is the observation that NADC30-like PRRSV with different recombination patterns exhibits varying pathogenicity, which has a significant impact on the pig farming industry. This emphasizes the necessity of monitoring and responding to evolving PRRSV strains to develop effective immunization and control strategies. In this paper, we conducted pathogenicity studies on the isolated NADC30-like PRRSV and analyzed the differences in the genomes and pathogenicity of the different strains by recording clinical symptoms, temperature changes, detoxification tests, and changes in viremia and histopathology in infected pigs. This was done to provide a theoretical basis for the epidemiological situation and epidemic prevention and control of PRRSV.