BACKGROUND AND OBJECTIVE

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as the causative agent of COVID-19 has significantly challenged the public health landscape in late 2019. After almost 3 years of the first ever SARS-CoV-2 case, the World Health Organization (WHO) declared the end of this global health emergency in May 2023. Although, despite the subsequent drop of COVID-19 cases, the SARS-CoV-2 infection still exhibited multiple waves of infection, primarily attributed to the appearance of new variants. Five of these variants have been classified as Variants of Concern (VOC): Alpha, Beta, Gamma, Delta, and the most recent, Omicron. Therefore, the development of methods for the timely and accurate detection of viral variants remains fundamental, ensuring an ongoing and effective response to the disease. This study aims to evaluate the feasibility of the application of an in-house approach in genomic surveillance for the detection of SARS-CoV-2 variants using in silico designed primers.

METHODS

The primers used for the study were particularly designed based on conserved regions of certain genes in the virus, targeting distinct mutations found in known variants of SARS-CoV-2. Viral RNA extracts from nasopharyngeal samples (n=14) were subjected to quantitative and qualitative tests (Nanodrop and AGE). Selected samples were then analyzed by RT-PCR and amplicons were submitted for sequencing. Sequence alignment analysis was carried out to identify the prevailing COVID-19 variant present in the sample population.

RESULTS

The study findings demonstrated that the in-house method was able to successfully amplify conserved sequences (spike, envelope, membrane, ORF1ab) and enabled identification of the circulating SARS-CoV-2 variant among the samples. Majority of the samples were identified as Omicron variant. Three out of four designed primers effectively bound into the conserved sequence of target genes present in the sample, revealing the specific SARSCoV-2 variant. The detected mutations characterized for Omicron found in the identified lineages included K417N, S477N, and P681H which were also identified as mutations of interest. Furthermore, identification of the B.1.448 lineage which was not classified in any known variant also provided the potential of the developed in-house method in detecting unknown variants of COVID-19.

CONCLUSION

Among the five VOCs, Omicron is the most prevalent and dominant variant. The in-house direct PCR product sequencing surveillance (DPPSS) method provided an alternative platform for SAR-CoV-2 variant analysis which is accessible and affordable than the conventional diagnostic surveillance methods and the whole genome sequencing. Further evaluation and improvements on the oligonucleotide primers may offer significant contribution to the development of a specific and direct PCRbased detection of new emerging COVID-19 variants.

Sars-cov-2 ; Polymerase Chain Reaction ; Dna Primers ; Oligonucleotide Primers ; Computer Simulation ; Conserved Sequence ; Coronavirus ; Covid-19 ; Disease ; Emergencies ; Evaluation Studies As Topic ; Genes ; Genome ; Global Health ; Health ; Identification (psychology) ; Infection ; Infections ; Membranes ; Methods ; Mutation ; Oligonucleotides ; Organizations ; Population ; Public Health ; Rna ; Rna, Viral ; Sars Virus ; Sequence Alignment ; Severe Acute Respiratory Syndrome ; Syndrome ; Viruses ; Whole Genome Sequencing ; World Health Organization

Gene synthesis is an enabling technology that supports the development of synthetic biology. The existing approaches for de novo gene synthesis generally have tedious operation, low efficiency, high error rates, and limited product lengths, being difficult to support the huge demand of synthetic biology. The assembly and error correction are the keys in gene synthesis. This study first designed the oligonucleotide sequences by reasonably splitting the virus genome of approximately 10 kb by balancing the parameters of sequence design software ability, PCR amplification ability, and assembly enzyme assembly ability. Then, two-step PCR was performed with high-fidelity polymerase to complete the de novo synthesis of 3.0 kb DNA fragments, and error correction reactions were performed with T7 endonuclease Ⅰ for the products from different stages of PCR. Finally, the virus genome was assembled by 3.0 kb DNA fragments from de novo synthesis and error correction and then sequenced. The experimental results showed that the proposed method successfully produced the DNA fragment of about 10 kb and reduced the probability of large fragment mutations during the assembly process, with the lowest error rate reaching 0.36 errors/kb. In summary, this study developed an efficient de novo method for synthesizing a viral genome of about 10 kb with T7 endonuclease Ⅰ-mediated error correction. This method enabled the synthesis of a 10 kb viral genome in one day and the correct plasmid of the viral genome in five days. This study optimized the de novo gene synthesis process, reduced the error rate, simplified the synthesis and assembly steps, and reduced the cost of viral genome assembly.
Genome, Viral/genetics* ; Polymerase Chain Reaction/methods* ; DNA, Viral/genetics* ; Bacteriophage T7/enzymology* ; Synthetic Biology/methods*

Foot-and-mouth disease (FMD) is one of the major animal infectious diseases in the world. All cloven-hoofed animals are susceptible to FMD. Vaccination is still the first choice for the prevention and control of FMD. mRNA vaccines can be rapidly designed, synthesized, and produced on a large scale in vitro, and they can induce effective protective immune responses, demonstrating the advantages of rapid development, easy preparation, and low biosafety risks. The design of untranslated regions is a key to enhancing the expression and efficacy of mRNA vaccines. In order to generate an efficient FMD mRNA vaccine, we designed three FMD P12A3C expression vectors with different untranslated regions and synthesized corresponding mRNAs. By comparing expression efficiency of these vectors and their mRNAs at different time points and in different cell lines, we found that the mRNA P12A3C-UTR3 had the best expression and universality. This study laid a foundation for the development of mRNA vaccines against FMD and provided a theoretical basis for the optimal sequence design of efficient mRNA.
Foot-and-Mouth Disease Virus/genetics* ; Animals ; RNA, Messenger/biosynthesis* ; Foot-and-Mouth Disease/immunology* ; Antigens, Viral/biosynthesis* ; Viral Vaccines/biosynthesis* ; Genetic Vectors/genetics* ; Cell Line ; Vaccines, DNA/immunology*

Geminiviruses cause substantial crop yield losses worldwide. The replication initiator protein (Rep) encoded by geminiviruses is indispensable for geminiviral replication. The Rep protein encoded by beet severe curly top virus (BSCTV, genus Curtovirus, family Geminiviridae) induces VARIANT IN METHYLATION 5 (VIM5) expression in Arabidopsis leaves upon BSCTV infection. VIM5 functions as a ubiquitination-related E3 ligase to promote the proteasomal degradation of methyltransferases, resulting in reduction of methylation levels in the BSCTV C2-3 promoter. However, the specific domains of Rep responsible for VIM5 induction remain poorly characterized. Although Rep proteins from several geminiviruses act as viral suppressors of RNA silencing (VSRs), whether BSCTV Rep also possesses VSR activity remains to be illustrated. In this study, we employed a transient expression system in the 16c-GFP transgenic and the wild-type Nicotiana benthamiana plants to analyze the VSR and the VIM5-inducing activities of different truncated Rep proteins haboring distinct domains. We found that the N-terminal domain (amino acids 1-180) of Rep suppressed GFP silencing in 16c-GFP transgenic N. benthamiana leaves. The minimal N-terminal fragment (amino acids 1-104) induced VIM5 expression upon co-infiltration, while C-terminal truncations lacked VIM5-inducing activity. Our results indicate that the N-terminal domain of Rep encoded by BSCTV mediates the suppression of RNA silencing and induces VIM5 expression. Thus, our findings contribute to a better understanding of interactions between geminiviral Rep and plant hosts.
Geminiviridae/genetics* ; Nicotiana/metabolism* ; Arabidopsis/metabolism* ; RNA Interference ; Viral Proteins/metabolism* ; Arabidopsis Proteins/metabolism* ; Plants, Genetically Modified/metabolism* ; Protein Domains ; Plant Diseases/virology* ; Methyltransferases/metabolism* ; Ubiquitin-Protein Ligases/metabolism* ; DNA Helicases/genetics*

OBJECTIVE: To investigate the pattern of hepatitis B virus (HBV) infection and the prevalence of hepatitis D virus (HDV) infection among voluntary blood donors who tested reactive for HBV in Wuhan, and to provide data support for the prevention and treatment of HBV and HDV infections. METHODS: Electrochemiluminescence (ECL) method was used to detect hepatitis B serological markers in the samples with HBsAg and/or HBV DNA reactivity, and the HBV infection in different groups was statistically analyzed. The HDV IgM and IgG antibodies were screened by ELISA, and the prevalence of HDV infection in the retained samples was analyzed. RESULTS: In 351 ELISA and/or nucleic acid test (NAT) reactive samples, the serological tests for hepatitis B revealed that 4 cases (1.1%) were positive for HBsAg, HBeAg, and anti-HBc, 182 cases (51.9%) were positive for HBsAg, anti-HBe, and anti-HBc, and 55 cases (15.7%) were negative for HBsAg but positive for anti-HBc. Among them, the HBsAg ELISA dual reagent reactive group (HBsAg R&R group) and the HBsAg ELISA single reagent reactive/HBV DNA reactive group (HBsAg R&NR/HBV DNA R group) had the highest rates of HBsAg(+), anti-HBe(+), and anti-HBc(+), accounting for more than 90% and 65%, respectively, followed by low activity of HBV acute infection or chronic carriers, accounting for about 5% and 20%, respectively. In the HBsAg R&NR/HBV DNA NR group, the combined proportion of individuals with anti-HBs single positive and all hepatitis B serological markers negative accounted for 78%, and those who were HBsAg negative but anti-HBc positive accounted for approximately 20%. In the HBsAg NR&NR/HBV DNA R group, there was nearly 9% of HBsAg(+), anti-HBe(+), and anti-HBc(+), the remaining were all HBsAg negative but anti-HBc positive, with a 100% anti-HBc positivity rate in this group. No HDV IgM or IgG antibodies were detected in the retained samples. CONCLUSION Blood donors with HBV-reactive results in blood screening exhibit multiple patterns of infection indicators. The prevalence rate of HDV infection among blood donors in Wuhan is extremely low. However, the risk of asymptomatic occult hepatitis B infection (OBI) blood donors being co-infected with HDV should not be overlooked in areas with high prevalence of HBV.
Humans ; Blood Donors ; Hepatitis B/blood* ; China/epidemiology* ; Adult ; Male ; Female ; Hepatitis D/epidemiology* ; Middle Aged ; Hepatitis B virus/immunology* ; Hepatitis B Antibodies/blood* ; Young Adult ; DNA, Viral/blood* ; Hepatitis B Surface Antigens/blood* ; Prevalence ; Adolescent

Female ; Humans ; Adenocarcinoma in Situ ; Uterine Cervical Neoplasms/pathology* ; Papillomavirus Infections ; Cervix Uteri/pathology* ; Adenocarcinoma/pathology* ; Papillomaviridae ; DNA, Viral

Porcine deltacoronavirus (PDCoV) is a major pathogen causing fatal diarrhea in suckling piglets, and there is currently a lack of effective vaccines and drugs to prevent and control the virus. The nonstructural protein 13 (NSP13) serves as a virus-coded helicase and is considered to be a crucial target for antiviral drugs, making it imperative to investigate the helicase activity of NSP13. In this study, the NSP13 gene of PDCoV was synthesized and integrated into the prokaryotic expression vector pET-28a to construct the recombinant plasmid pET-28a-NSP13. NSP13 was successfully expressed in BL21 (DE3) and subsequently purified. The study also verified the helicase activity of the purified NSP13 and explored the factors that influence this activity. The results indicated that NSP13 from PDCoV was effectively expressed in the prokaryotic system and exhibited helicase activity, capable of unwinding double-stranded DNA with a tail at the 5' end. Additionally, NSP13 demonstrated an annealing function by promoting the complementary pairing of single-stranded nucleotide chains to form double strands. The helicase activity of NSP13 was affected by metal ions, but Mg²⁺concentrations in the range of 0.5-6.0 mmol/L had no significant effect on helicase activity of NSP13. When the solution pH was in the range of 4-9, there was no difference in helicase activity. ATP concentrations in the range of 0.25-6.00 mmol/L had a weak effect on helicase activity, and NSP13 concentration ≥80 nmol/L inhibited the helicase activity. We obtained the NSP13 of PDCoV and investigated its helicase activity. These findings provided a theoretical foundation for the further research on the regulatory mechanism of NSP13 in PDCoV replication and the development of anti-coronaviral drugs.
Viral Nonstructural Proteins/metabolism* ; Escherichia coli/metabolism* ; Recombinant Proteins/metabolism* ; Swine ; Animals ; DNA Helicases/metabolism* ; Genetic Vectors/metabolism*

Objective: To determine the optimal cutoff value of Epstein-Barr virus (EBV) DNA load that can assist in the diagnosis of post-transplant lymphoproliferative disease (PTLD) after haploidentical hematopoietic stem cell transplantation (haplo-HSCT) . Methods: The data of patients with EBV infection after haplo-HSCT from January to December 2016 were retrospectively analyzed. Through constructing the receiver operating characteristic (ROC) curve and calculating the Youden index to determine the cutoff value of EBV-DNA load and its duration of diagnostic significance for PTLD. Results: A total of 94 patients were included, of whom 20 (21.3% ) developed PTLD, with a median onset time of 56 (40-309) d after transplantation. The median EBV value at the time of diagnosis of PTLD was 70,400 (1,710-1,370,000) copies/ml, and the median duration of EBV viremia was 23.5 (4-490) d. Binary logistic regression was used to analyze the peak EBV-DNA load (the EBV-DNA load at the time of diagnosis in the PTLD group) and duration of EBV viremia between the PTLD and non-PTLD groups. The results showed that the difference between the two groups was statistically significant (P=0.018 and P=0.001) . The ROC curve was constructed to calculate the Youden index, and it was concluded that the EBV-DNA load ≥ 41 850 copies/ml after allogeneic hematopoietic stem cell transplantation had diagnostic significance for PTLD (AUC=0.847) , and the sensitivity and specificity were 0.611 and 0.932, respectively. The duration of EBV viremia of ≥20.5 d had diagnostic significance for PTLD (AUC=0.833) , with a sensitivity and specificity of 0.778 and 0.795, respectively. Conclusion: Dynamic monitoring of EBV load in high-risk patients with PTLD after haplo-HSCT and attention to its duration have important clinical significance, which can help clinically predict the occurrence of PTLD in advance and take early intervention measures.
Humans ; Epstein-Barr Virus Infections/diagnosis* ; Herpesvirus 4, Human/genetics* ; Retrospective Studies ; Viremia ; Hematopoietic Stem Cell Transplantation/adverse effects* ; Lymphoproliferative Disorders/etiology* ; DNA, Viral ; Viral Load

Objective: This article investigated the clinical characteristics and distribution of drug resistance mutation sites in HBV RT region of hepatitis B infected patients. Methods: Retrospective analysis was made on 1 948 patients with HBV infection, who had been tested for NAs resistance mutation and had a medical history of NAs in the Laboratory Department of the Fifth Medical Center of the PLA General Hospital from January 2020 to December 2021. Basic clinical information and drug resistance related mutation information were recorded. Meanwhile, the serological index data of hepatitis B were collected. Drug resistance gene mutant group and non-mutated group were grouped according to whether the drug resistance genes had a mutation in HBV RT region, and the clinical characteristics and genotype distribution of the two groups were statistically analyzed. The pattern of drug resistance gene mutation, number of mutation sites, drug resistance type and mutation of NAs resistance-related sites were analyzed in 917 patients with drug resistance gene mutation in HBV RT region. χ² Inspection was used for counting data. Meanwhile, two independent samples t-test and Wilcoxon rank sum test were used for measurement data. Results: Among the 1 948 patients with chronic HBV infection, 917 patients had drug resistance gene mutation in RT region (47.07%). The proportion of patients with acute hepatitis B and CHB in HBV RT resistance gene mutant group was lower than that in the non-mutated group, while the proportion of patients with HBV-related cirrhosis was higher than that in the non-mutated group, these differences were statistically significant. Compared with the non-mutated group in HBV RT region, the age, the positive rates of HBeAg and HBV DNA, and HBV DNA load of these patients were increased in drug resistance gene mutant group, these differences were statistically significant. Genotypes of patients in both groups were dominated by C, followed by B and D. The proportion of patients with genotype C in HBV RT drug resistance gene mutant group was higher than that of non-mutated group, the difference was statistically significant. There were 53 gene mutation patterns in 917 patients with drug resistance gene mutation in HBV RT region, and the main pattern was rtL180M+rtM204V+rtS202G (9.70%). The mutation sites were dominated by 3 (20.74%). There were 5 types of drug resistance, LAM+Ldt (21.25%) was the most. Among the 18 sites that were clearly associated with LAM, ADV, ETV and Ldt resistance in the HBV RT region, 14 sites were mutated, and the most common mutation sites were rtL180M, rtM204V, rtM204 and rtS202G. what's more, the proportion of patients with NAs drug resistance was LAM>Ldt>ETV>ADV. Conclusion: In order to prevent adverse consequences of this study such as disease recurrence or disease progression caused by HBV drug resistance, HBV infected patients, who have long-term use of NAs antiviral therapy, should monitor the level of HBV DNA and drug resistance genes in HBV RT region in order to optimize the treatment plan in time or guide individualized treatment.
Humans ; Hepatitis B virus/genetics* ; Hepatitis B, Chronic ; Antiviral Agents/therapeutic use* ; DNA, Viral/therapeutic use* ; Retrospective Studies ; Mutation ; Drug Resistance, Viral/genetics* ; Lamivudine/therapeutic use*

Humans ; Squamous Cell Carcinoma of Head and Neck ; RNA, Messenger ; Immunohistochemistry ; Papillomavirus Infections/diagnosis* ; Oncogene Proteins, Viral/genetics* ; Head and Neck Neoplasms ; Cyclin-Dependent Kinase Inhibitor p16 ; Papillomaviridae ; Papillomavirus E7 Proteins/genetics* ; DNA, Viral