Criteria for second generation comparator tests in validation of novel HPV DNA tests for use in cervical cancer screening.

While HC2 and GP5+/6+ PCR-EIA were pivotal in test validation of new HPV assays, they represent the first generation of comparator tests based upon technologies that are not in widespread use anymore. In the current guideline, criteria for second-generation comparator tests are presented that include more detailed resolution of HPV genotypes. Second-generation comparator tests should preferentially target only the 12 genotypes classified as carcinogenic (IARC-group I), and show consistent non-inferior sensitivity for CIN2+ and CIN3+ and specificity for ≤CIN1 compared to one of the first-generations comparators, in at least three validation studies using benchmarks of 0.95 for relative sensitivity and 0.98 for relative specificity. Validation should take into account used storage media and other sample handling procedures. Meta-analyses were conducted to identify the assays that fulfill these stringent criteria. Four tests fulfilled the new criteria: (1) RealTime High-Risk HPV Test (Abbott), (2) Cobas-4800 HPV test (Roche Molecular System), (3) Onclarity HPV Assay (BD Diagnostics), and (4) Anyplex II HPV HR Detection (Seegene), each evaluated in three to six studies. Whereas the four assays target 14 carcinogenic genotypes, the first two identify separately HPV16 and 18, the third assay identifies five types separately and the fourth identifies all the types separately.

An electrochemiluminescent imaging strategy based on CRISPR/Cas12a for ultrasensitive detection of nucleic acid.

BACKGROUND: Persistent infection with human papillomavirus (HPV) significantly contributes to the development of cervical cancer. Thus, it is urgent to develop rapid and accurate methods for HPV detection. Herein, we present an ultrasensitive CRISPR/Cas12a-based electrochemiluminescent (ECL) imaging technique for the detection of HPV-18 DNA. RESULT: The ECL DNA sensor array is constructed by applying black hole quencher (BHQ) and polymer dots (Pdots) co-labeled hairpin DNA (hpDNA) onto a gold-coated indium tin oxide slide (Au-ITO). The ECL imaging method involves an incubation process of target HPV-18 with a mixture of crRNA and Cas12a to activate Cas12a, followed by an incubation of the active Cas12a with the ECL sensor. This interaction causes the indiscriminate cleavage of BHQ from Pdots by digesting hpDNA on the sensor surface, leading to the restoration of the ECL signal of Pdots. The ECL brightness readout demonstrates superior performance of the ECL imaging technique, with a linear detection range of 10 fM-500 pM and a limit-of-detection (LOD) of 5.3 fM. SIGNIFICANCE: The Cas12a-based ECL imaging approach offers high sensitivity and a broad detection range, making it highly promising for nucleic acid detection applications.

The level of expression of HPV16 early transcripts is not associated with the natural history of cervical lesions.

The natural history of cervical cancer is closely linked to that of high-risk human papillomaviruses (HPV) infection. It is recognized that upon HPV DNA integration, partial or complete loss of the E2 open reading frame precludes expression of the corresponding protein, resulting in upregulation of the E6 and E7 viral oncoproteins. To better characterize HPV16 infection at the cervical level, viral load, viral DNA integration, and viral early transcript expression (E2, E5, and E6) were analyzed in a series of 158 cervical specimens representative of the full spectrum of cervical disease. Overall, the frequency of early transcript detection varied from 45% to 90% and tended to increase with lesion severity. In addition, the levels of E2, E5, and E6 transcript expression were slightly higher in high-grade lesions than in cervical specimens without abnormalities. Notably, early transcript expression was clearly associated with viral load, and no inverse correlation was found between the expression of E2 and E6 transcripts. No clear association was found between early transcript expression and HPV16 DNA integration, with the exception that samples with a fully integrated HPV16 genome did not harbor E2 or E5 transcripts. In conclusion, early HPV16 transcript expression appears to be associated with viral load rather than lesion grade. From a practical point of view, quantification of HPV16 early transcripts is difficult to translate into a relevant biomarker for cervical cancer screening.

2024 taxonomy update for the family Circoviridae.

Circovirids have a circular single-stranded DNA genome packed into a small icosahedral capsid. They are classified within two genera, Circovirus and Cyclovirus, in the family Circoviridae (phylum Cressdnaviricota, class Arfiviricetes, order Cirlivirales). Over the last five years, a number of new circovirids have been identified, and, as a result, 54 new species have been created for their classification based on the previously established species demarcation criterion, namely, that viruses classified into different species share less than 80% genome-wide pairwise sequence identity. Of note, one of the newly created species includes a circovirus that was identified in human hepatocytes and suspected of causing liver damage. Furthermore, to comply with binomial species nomenclature, all new and previously recognized species have been (re)named in binomial format with a freeform epithet. Here, we provide a summary of the properties of circovirid genomes and their classification as of June 2024 (65 species in the genus Circovirus and 90 species in the genus Cyclovirus). Finally, we provide reference datasets of the nucleotide and amino acid sequences representing each of the officially recognized circovirid species to facilitate further classification of newly discovered members of the Circoviridae.

DNA and seroprevalence study of MW and STL polyomaviruses.

The clinical importance and the pathogenesis of the MW and STL polyomaviruses (PyVs) remain unclear. Our aim was to study the seroprevalence of MWPyV and STLPyV, and to examine the prevalence of viral DNA in respiratory samples and secondary lymphoid tissues. In total, 618 serum samples (0.8-90 years) were analyzed for seroprevalence. For the DNA prevalence study, 146 patients (2.5-37.5 years) were sampled for adenoids (n = 100), tonsils (n = 100), throat swabs (n = 146), and middle ear discharge (n = 15) in study Group 1. In Group 2, we analyzed 1130 nasopharyngeal samples from patients (0.8-92 years) tested for SARS-CoV-2 infection. The adult seropositivity was 54% for MWPyV, and 81.2% for STLPyV. Both seroprevalence rates increased with age; however, the majority of STLPyV primary infections appeared to occur in children. MWPyV was detected in 2.7%-4.9% of respiratory samples, and in a middle ear discharge. STLPyV DNA prevalence was 1.4%-3.4% in swab samples, and it was detected in an adenoid and in a middle ear discharge. The prevalence of both viruses was significantly higher in the children. Noncoding control regions of both viruses and the complete genomes of STLPyV were sequenced. MWPyV and STLPyV are widespread viruses, and respiratory transmission may be possible.

Ultrafast DNA detection based on turn-back loop primer-accelerated LAMP (TLAMP).

Rapid DNA detection is a long-pursuing goal in molecular detection, especially in combating infectious diseases. Loop-mediated isothermal amplification (LAMP) is a robust and prevailing DNA detection method in pathogen detection, which has been drawing broad interest in improving its performance. Herein, we reported a new strategy and developed a new LAMP variant named TLAMP with a superior amplification rate. In this strategy, the turn-back loop primers (TLPs) were devised by ingeniously extending the 5' end of the original loop primer, which conferred the new role of being the inner primer for TLPs while retaining its original function as the loop primer. In theory, based on the bifunctional TLPs, a total of eight basic dumbbell-like structures and four cyclic amplification pathways were produced to significantly enhance the amplification efficiency of TLAMP. With the enhancing effect of TLPs, TLAMP exhibited a significantly reduced amplification-to-result time compared to the conventional six-primer LAMP (typically 1 h), enabling rapid DNA detection within 20 min. Furthermore, TLAMP proved to be about 10 min faster than the fast LAMP variants reported so far, while still presenting comparable sensitivity and higher repeatability. Finally, TLAMP successfully achieved an ultrafast diagnosis of Monkeypox virus (MPXV), capable of detecting as few as 10 copies (0.67copies/µL) of pseudovirus within 20 min using real-time fluorescence assay or within 30 min using a colorimetric assay, suggesting that the proposed TLAMP offers a sensitive, specific, reliable, and, most importantly, ultrafast DNA detection method when facing the challenges posed by infectious diseases.

Uncommon high distribution of HPV-16, HPV-54, and HPV-56 in female referred to a laboratory in Karaj, Iran: indications of a paradigm shift in HPV genotypes?

BACKGROUND: Human papillomavirus (HPV) is among the leading cause of sexually transmitted infections, particularly prevalent among sexually active individuals. While many HPV infections clear up over time, some may progress to various cancers such as anal cancer, cervical cancer and, vaginal cancer. This study examines the prevalence of different HPV genotypes, classified as high-risk (HR) and low-risk (LR), among females of various age groups who visited the laboratory in Karaj. MATERIAL AND METHODS: Genital specimens were gathered from the individuals involved in the study and subjected to DNA extraction (DNA/RNA extraction AmpliSense, Moscow, Russia) followed by amplification using Real-Time PCR. HR- and LR-HPV genotypes were identified using the GenoFlow HPV Array test kit (GenoFlow; DiagCor Bioscience, Hong Kong) and homemade HPV genotyping kit. Demographic information such as age, was examined alongside statistical virological data. RESULTS: Overall, 367 (17%) out of the 2109 (100%) female cases tested positive for HPV. Among these, 219 (46.2%) were classified as low-risk, 44 (9.3%) as potentially high-risk, and 211 (44.5%) as high-risk. The highest percentage of positive test results was detected in individuals under 30 years old (35%) and those aged 40-50 (18%). Individuals in the < 30 age group were primarily infected with HR genotypes. The most commonly identified genotypes overall were HPV-16 (11.7%), HPV-54 (10.3%), HPV-56 (8.4%), HPV-40 (8.1%). The lowest frequency was observed for HPV-70, HPV-71, HPV-82, and HPV-90, each recorded in only a single case. CONCLUSION: Our results highlight the notable occurrence of HPV among females who visited the laboratory in Karaj, especially in the < 30 age group. Identifying HPV-16 as the most prevalent genotype in our examination highlights the necessity of tailored interventions for specific age ranges. While HPV-16 is covered by vaccination programs, HPV-54 and HPV-56 are not, emphasizing the need for effective screening and preventive plans to manage the consequences of HPV-related diseases in future.

Comparison of multiplex PCR capillary electrophoresis assay and PCR-reverse dot blot assay for human papillomavirus DNA genotyping detection in cervical cancer tissue specimens.

Background: The study aimed to evaluate the positivity rates and genotype distribution of the multiplex PCR capillary electrophoresis (MPCE) and PCR-Reverse Dot Blot (PCR-RDB) assays for human papillomavirus (HPV) detection in cervical cancer tissue specimens, and to explore their detection principles and applications in large-scale population screening. Methods: The MPCE and PCR-RDB assays were performed separately on 425 diagnosed cervical cancer tissue specimens. Subsequently, the results of both assays were compared based on the HPV infection positivity rates and genotype distribution. Results: The overall positive rates of HPV genotypes for the MPCE and PCR-RDB assays were 97.9% and 92.9%, respectively. A p-value < 0.001 indicated a statistically significance difference in consistency between the two assays. The kappa value was 0.390, indicating that the consistency between both assays was fair. HPV16 was the most common single-genotype infection type, with infection rates detected via MPCE and PCR-RDB assays being 75.7% and 68.3%, respectively. In the age group >50 years, the HPV multiple-type infection rate detected via MPCE assay was significantly higher than that detected by the PCR-RDB assay, with a statistically significant difference (p = 0.002). Conclusion: To reduce the false-negative rate and improve screening efficiency, the MPCE assay, which targets the oncogenic gene E6/E7 segments, can be extended to the general female population for the early detection, diagnosis, and treatment of cervical cancer.

Real-time PCR assay to detect the novel Clade Ib monkeypox virus, September 2023 to May 2024.

Monkeypox virus (MPXV) is an emerging zoonotic pathogen with complex epidemiology necessitating rapid diagnosis and distinguishing between clades and subclades. The emerging Clade Ib lacks the genomic region used in the Clade I-specific assay from the Centers for Disease Control and Prevention. We report an MPXV real-time PCR to specifically detect Clade Ib. The assay demonstrated proficient sensitivity and specificity in 92 samples and can be included along other TaqMan-based assays to detect MPXV and distinguish between clades and subclades.

Prevalence and genotype distribution of human papillomavirus infection among 66000 women from 2014 to 2023 in the plateau region of Southwest China.

BACKGROUND: Persistent infection with high-risk human papillomavirus (HR-HPV) plays a key role in the onset of cervical cancer. This study was designed to examine the epidemiological trends and genotype distribution of HPV from 2014 to 2023 in the plateau region of Southwest China. METHODS: The findings could offer valuable insights for clinical screening of cervical cancer and the formulation of HPV vaccination policies. This retrospective study analyzed 66,000 women who received HPV-DNA testing at the First People's Hospital of Qujing, Yunnan, China, between 2014 and 2023. The cohort consisted of 33,512 outpatients, 3,816 inpatients, and 28,672 individuals undergoing health examinations. Cervical cells were collected for DNA extraction, and PCR amplification along with Luminex xMAP technology were used to detect 27 HPV genotypes. The data analysis was conducted using GraphPad Prism and IBM SPSS Statistics 27 software. RESULTS: The overall HPV infection rate at the First People's Hospital of Qujing declined from 24.92% in 2014 to 16.29% in 2023, averaging 16.02%. Specific infection rates were 18.50% among outpatients, 12.97% among inpatients, and 13.53% for health examination attendees. The predominant high-risk HPV genotypes identified were HPV52 (2.61%), HPV16 (2.06%), HPV58 (1.81%), HPV53 (1.55%), and HPV39 (1.09%). Meanwhile, the most frequent low-risk HPV genotypes were HPV6 (1.30%), HPV61 (1.21%), and HPV11 (0.85%). In HPV-positive cases, the distribution of single, double, triple, and quadruple or more infections were 79.90%, 15.17%, 3.59%, and 1.33%, respectively. The proportions of pure LR-HPV, pure HR-HPV, and mixed infections were 22.16%, 67.82%, and 10.02%, respectively. Age-specific analysis revealed a bimodal distribution of HPV infection, with the infection rate rapidly decreasing from 44.02% in the ≤ 19 age group to 19.55% in the 20-29 age group and 13.84% in the 30-39 age group, followed by a gradual increase to 14.64% in the 40-49 age group, 16.65% in the 50-59 age group, and 22.98% in the ≥ 60 age group. The coverage rates of the three available vaccines are all below 50%. The results of this study indicated a declining trend in HPV prevalence in the plateau region of Southwest China over the period from 2014 to 2023, especially in the reduction of genotypes targeted by vaccines. CONCLUSION: There were significant variations in the genotypes prevalent among different age groups, years, and patient sources within the same region. The underwhelming vaccination rates emphasize the critical need for developing either a multivalent vaccine or a personalized vaccine that targets the HPV genotypes common in the Chinese population. Furthermore, vaccinating adolescents to curb HPV infection and ensuring regular cervical cancer screenings for postmenopausal women are crucial steps.

Molecular findings and virological assessment of bladder papillomavirus infection in cattle.

Bovine and ovine papillomaviruses (BPVs - OaPVs) are infectious agents that have an important role in bladder carcinogenesis of cattle. In an attempt to better understand territorial prevalence of papillomavirus genotypes and gain insights into their molecular pathway(s), a virological assessment of papillomavirus infection was performed on 52 bladder tumors in cattle using droplet digital polymerase chain reaction (ddPCR), an improved version of conventional PCR. ddPCR detected and quantified BPV DNA and mRNAs in all tumor samples, showing that these viruses play a determinant role in bovine bladder carcinogenesis. OaPV DNA and mRNA were detected and quantified in 45 bladder tumors. BPV14, BPV13, BPV2, OaPV2, OaPV1, and OaPV3 were the genotypes most closely related to bladder tumors. ddPCR quantified BPV1 and OaPV4 DNA and their transcripts less frequently. Western blot analysis revealed a significant overexpression of the phosphorylated platelet derived growth factor ß receptor (PDGFßR) as well as the transcription factor E2F3, which modulate cell cycle progression in urothelial neoplasia. Furthermore, significant overexpression of calpain1, a Cys protease, was observed in bladder tumors related to BPVs alone and in BPV and OaPV coinfection. Calpain1 has been shown to play a role in producing free transcription factors of the E2F family, and molecular findings suggest that calpain family members work cooperatively to mutually regulate their protease activities in cattle bladder tumors. Altogether, these results showed territorial prevalence of BPV and OaPV genotypes and suggested that PDGFßR and the calpain system appeared to be molecular partners of both BPVs and OaPVs.

Proximity ligation-based sequencing for the identification of human papillomavirus genomic integration sites in formalin-fixed paraffin embedded oropharyngeal squamous cell carcinomas.

Human papillomavirus (HPV) infections are an increasing cause of oropharyngeal squamous cell carcinomas (OPSCC). Integration of the viral genome into the host genome is suggested to affect carcinogenesis, however, the correlation with OPSCC patient prognosis is still unclear. Research on HPV integration is hampered by current integration detection technologies and their unsuitability for formalin-fixed paraffin-embedded (FFPE) tissues. This study aims to develop and validate a novel targeted proximity-ligation based sequencing method (targeted locus amplification/capture [TLA/TLC]) for HPV integration detection in cell lines and FFPE OPSCCs. For the identification of HPV integrations, TLA/TLC was applied to 7 cell lines and 27 FFPE OPSCCs. Following preprocessing steps, a polymerase chain reaction (PCR)-based HPV enrichment was performed on the cell lines and a capture-based HPV enrichment was performed on the FFPE tissues before paired-end sequencing. TLA was able to sequence up to hundreds of kb around the target, detecting exact HPV integration loci, structural variants, and chromosomal rearrangements. In all cell lines, one or more integration sites were identified, in accordance with detection of integrated papillomavirus sequences PCR data and the literature. TLC detected integrated HPV in 15/27 FFPE OPSCCs and identified simple and complex integration patterns. In general, TLA/TLC confirmed PCR data and detected additional integration sites. In conclusion TLA/TLC reliably and robustly detects HPV integration in cell lines and FFPE OPSCCs, enabling large, population-based studies on the clinical relevance of HPV integration. Furthermore, this approach might be valuable for clonality assessment of HPV-related tumors in clinical diagnostics.

Southern African Origin of HTLV-1 in Romania.

In Europe, most HTLV-1-infected individuals originate from highly endemic regions such as West Indies, sub-Saharan Africa, and South America. The only genuine endemic region for HTLV-1 in Europe is Romania where ATL series have been reported among Romanian patients. Our objective is to better understand the origin of this endemic focus based on a study of the genetic diversity of HTLV-1 in Romanians. DNA was obtained from PBMCs/buffy coats of 11 unrelated HTLV-1-infected individuals of Romanian origin. They include 9 ATL cases and 2 asymptomatic carriers. LTR sequences were obtained for all specimens. Complete genomic HTLV-1 sequences were obtained using four PCR series on 10 specimens. Phylogenetic trees were generated from multiple alignments using HTLV-1 prototypic sequences and the new generated sequences. Most of the complete LTR sequences (756-bp) showed low nucleotide diversity, ranging from 0% to 0.8% difference, and were closely related (less than 0.8% divergence) to the only previously characterized Romanian strain, RKI2. One strain, ROU7, diverged slightly (1.5% on average) from the others. Phylogenetic analyses both on partial LTR and the complete genome demonstrate that the 11 sequences belong to the HTLV-1a cosmopolitan genotype and 10 of them belong to the previously denominated a-TC Mozambique-Southern Africa A subgroup. In this study, we demonstrated that the HTLV-1 present in Romania most probably originated in Southern Africa. As most Romanian HTLV-1 strains are very closely related, we can assume that HTLV-1 has been introduced into the Romanian population recently. Further studies are ongoing to decipher the routes of arrival and dissemination of these HTLV-1 strains, and to date the emergence of this endemic focus in Central Europe.

Performance evaluation of the Allplex HPV HR Detection assay in comparison with the Cobas HPV test for high-risk HPV genotyping.

Molecular testing for high-risk human papillomavirus (hrHPV) genotypes is important in screening for cervical cancer. In this study, we evaluated the performance of a newly developed Allplex HPV HR Detection assay in comparison with the Cobas HPV Test. A total of 1,275 cervical specimens obtained from a healthcare center between August 2021 and May 2022 were analyzed. The overall agreement for hrHPV detection was 98.4%, with higher agreement observed for HPV-16 (99.7%) and HPV-18 (99.8%) compared to other hrHPV genotypes (97.2%). Sequencing revealed that the majority of discrepancies was genotyped accurately by the Allplex HPV HR Detection assay with the exception of one false positive for HPV-16 and two false positives for other hrHPV genotypes. The Allplex HPV HR Detection assay showed almost perfect agreement with the Cobas HPV test, emphasizing its utility in hrHPV screening and monitoring.

An In-Depth Approach to the Associations between MicroRNAs and Viral Load in Patients with Chronic Hepatitis B-A Systematic Review and Meta-Analysis.

Scientists study the molecular activities of the hepatitis B virus (HBV). However, in vivo experiments are scarce. Some microRNAs are HBV-related, but their exact mechanisms are unknown. Our study provides an up-to-date view of the associations between microRNAs and HBV-DNA levels in chronically infected individuals. We conducted this large-scale research on five databases according to PRISMA guidance. Joanna Briggs Institute tools and Newcastle Ottawa Quality Assessment scores helped with quality evaluations. R 4.2.2 performed statistical computations for the meta-analysis. DIANA-microT 2023 and g:Profiler enriched the predictions of liver genes associated with miR-122 and miR-192-5p. From the 1313 records, we eliminated those irrelevant to our theme, non-article methodologies, non-English entries, and duplicates. We assessed associations between microRNAs and HBV-DNA levels. Overall, the pooled correlations favoured the general idea of the connection between non-coding molecules and viremia levels. MiR-122 and miR-192-5p were the most researched microRNAs, significantly associated with HBV-DNA levels. The connections between miR-122, miR-192-5p, let-7, miR-215, miR-320, and viral loads need further in vivo assessment. To conclude, this study evaluates systematically, for the first time, the correlations between non-coding molecules and viremia levels in patients. Our meta-analysis emphasizes potentially important pathways toward new inhibitors of the viral replication cycle.

A new evaluation of the rearranged non-coding control region of JC virus in patients with colorectal cancer.

BACKGROUND: Several studies have reported the presence of JC virus (JCV) in human tumors, The association of JCV and CRC remains controversial. This study aimed to evaluate the rearranged NCCR region of the detected JCV DNA in CRC patients' tissue samples. METHODS: In this case-control study, tumor tissues (n = 60), adjacent normal tissues (n = 60), and urine samples (n = 60) of the CRC patients were collected. The nested PCR was employed to detect the VP1 and NCCR regions of the JCV genome. The positive JCV PCR products were sequenced and a phylogenetic tree was constructed to determine the JCV genotypes. After extracting RNA and preparing cDNA, the expression of JCV LTAg was examined in 60 tumor tissues and 60 adjacent normal tissues. The analysis of JCV LTAg expression was performed using GraphPad Prism software version 8. RESULTS: The analysis reveals that JCV DNA was detected in 35/60 (58.3%) tumor tissues, while 36/60 (60.0%) of adjacent normal tissues (p = 0.85). JCV DNA was detected in 42/60 (70.0%) urine samples when compared to 35/60 (58.3%) tumor tissues of CRC patients and was not found significant (P = 0.25). The phylogenetic tree analysis showed the dominant JCV genotype 3, followed by genotype 2D was distributed in tumor tissue, normal tissue, and urine samples of the CRC patients. Analysis of randomly selected NCCR sequences from JCV regions in tumor tissue samples revealed the presence of rearranged NCCR blocks of different lengths.: 431 bp, 292 bp, 449 bp, and 356 bp. These rearranged NCCR blocks differ from the rearranged NCCR blocks described in PML-type Mad-1, Mad-4, Mad-7, and Mad-8 prototypes. The expression of JCV LTAg was significantly different in tumor tissue compared to normal tissue, with a p-value of less than 0.002. CONCLUSION: A significant proportion of 35%> of the tumor tissue and urine samples of the CRC patients was found to be positive for JCV DNA (P = 0.25). The parallel analysis of tumor and urine samples for JCV DNA further supports the potential for non-invasive screening tools. This study provides new insights into Rearranged NCCR variant isolates from patients with CRC. The significant difference in JCV LTAg expression between tumor and normal tissue indicates a latent JCV status potentially leading to cancer development.

In Situ Colorimetric LAMP Based on One-Step Modified Filter Paper to Screen Human Papillomavirus (HPV)16/18 from Clinical Samples.

Cervical cancer is among the most common malignant tumors in women. The development of rapid screening techniques plays an important role in early screening for cancer treatment. We have developed an HPV screening method, which effectively combines the high-efficiency nucleic acid enrichment of chitosan-modified filter paper and the rapid visual detectability of colorimetric LAMP, along with the enhancement of the tolerance ability of the pH-sensitive LAMP reagent to acidic original samples, making the detection of HPV 16/18 easy to carry out and reliable, which is helpful for the epidemiological prevention and control strategies of HPV-induced cancer. This technique can simultaneously exhibit the "in situ amplification" capability of chitosan-modified filter paper and the nontemperature cycle dependence of visual LAMP detection. Therefore, DNA extraction and amplification can be performed efficiently and quickly within a single reaction where all DNA is concentrated in the QF paper disc. By embedding amino-modified filter paper into the plastic chip, a simple and reliable disposable chip was prepared for rapid HPV16 and HPV18 detection from clinical endometrial samples, and the results were 100% consistent with clinical diagnosis. More importantly, even after the sample was diluted 100-fold, HPV16/18-infected cells could be accurately identified, showing the advantages of the system in early cancer screening. Moreover, for endometrial samples containing plenty of cells, the filter paper could be used to enrich cells by filtration, preventing the acidic fluid from impacting pH-induced colorimetric LAMP detection and realizing direct amplification for HPV identification without nucleic acid extraction. This easy-to-operate system that can analyze a wide range of samples will be suitable for routine on-site HPV screening, dramatically extending the applications and utility for rapid, near-patient nucleic acid testing.

Structures of African swine fever virus topoisomerase complex and their implications.

African swine fever virus (ASFV) is the causal agent of African swine fever (ASF), which is contagious and highly lethal to domestic pigs and wild boars. The genome of ASFV encodes many proteins important for ASFV life cycle. The functional importance of topoisomerase AsfvTopII has been confirmed by in vivo and in vitro assays, but the structure of AsfvTopII is poorly studied. Here, we report four AsfvTopII complex structures. The ATPase domain structures reveal the detailed basis for ATP binding and hydrolysis, which is shared by AsfvTopII and eukaryotic TopIIs. The DNA-bound structures show that AsfvTopII follows conserved mechanism in G-DNA binding and cleavage. Besides G-DNA, a T-DNA fragment is also captured in one AsfvTopII structure. Mutagenesis and in vitro assays confirm that Pro852 and the T-DNA-binding residue Tyr744 are important for the function of AsfvTopII. Our study not only advances the understanding on the biological function of AsfvTopII, but also provides a solid basis for the development of AsfvTopII-specific inhibitors.

Structural basis for DNA recognition by a viral genome-packaging machine.

DNA recognition is critical for assembly of double-stranded DNA viruses, particularly for the initiation of packaging the viral genome into the capsid. The key component that recognizes viral DNA is the small terminase protein. Despite prior studies, the molecular mechanism for DNA recognition remained elusive. Here, we address this question by identifying the minimal site in the bacteriophage HK97 genome specifically recognized by the small terminase and determining the structure of this complex by cryoEM. The circular small terminase employs an entirely unexpected mechanism in which DNA transits through the central tunnel, and sequence-specific recognition takes place as it emerges. This recognition stems from a substructure formed by the N- and C-terminal segments of two adjacent protomers which are unstructured when DNA is absent. Such interaction ensures continuous engagement of the small terminase with DNA, enabling it to slide along the DNA while simultaneously monitoring its sequence. This mechanism allows locating and instigating packaging initiation and termination precisely at the specific cos sequence.

Structures of Mature and Urea-Treated Empty Bacteriophage T5: Insights into Siphophage Infection and DNA Ejection.

T5 is a siphophage that has been extensively studied by structural and biochemical methods. However, the complete in situ structures of T5 before and after DNA ejection remain unknown. In this study, we used cryo-electron microscopy (cryo-EM) to determine the structures of mature T5 (a laboratory-adapted, fiberless T5 mutant) and urea-treated empty T5 (lacking the tip complex) at near-atomic resolutions. Atomic models of the head, connector complex, tail tube, and tail tip were built for mature T5, and atomic models of the connector complex, comprising the portal protein pb7, adaptor protein p144, and tail terminator protein p142, were built for urea-treated empty T5. Our findings revealed that the aforementioned proteins did not undergo global conformational changes before and after DNA ejection, indicating that these structural features were conserved among most myophages and siphophages. The present study elucidates the underlying mechanisms of siphophage infection and DNA ejection.