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 explore the characteristics of plasma Epstein-Barr virus (EBV) DNA in primary infection in pediatric cases. Methods: The laboratory and clinical data of 571 children diagnosed with EBV primary infection in Children's Hospital of Fudan University during September 1^st, 2017 to September 30^th, 2018 were retrospectively analyzed. According to the results of plasma EBV DNA, they were divided into positive group and negative group. According to the EBV DNA, they were devided into high plasma virol load group and low plasma virol load group. The Chi-square test, Wilcoxon rank sum test were used to compare the differences between groups. Results: Among the 571 children with EBV primary infection, 334 were males and 237 were females. The age of first diagnosis was 3.8 (2.2, 5.7) years. There were 255 cases in positive group and 316 cases in negative group. The percentage of cases with fever,hepatomegaly and (or) splenomegaly, elevated transaminase in the positive group were higher than those in the negative group (235 cases (92.2%) vs. 255 cases (80.7%), χ²=15.22, P<0.001; 169 cases (66.3%) vs. 85 cases (26.9%), χ²=96.80, P<0.001; and 144 cases (56.5%) vs. 120 cases (38.0%), χ²=18.27, P<0.001; respectively).In the positive group, 70 cases were followed up for 46 (27, 106) days, 68 cases (97.1%) turned negative within 28 days, with the exception of 2 cases (2.9%) developed chronic active EBV infection by follow-up revision.There were 218 cases in high plasma viral DNA copies group and 37 cases in low copies group. More cases presented with elevated transaminases in the high plasma viral DNA copies group than those in the low group (75.7% (28/37) vs. 56.0%(116/207), χ²=5.00, P=0.025).Both the positive rate of EBV DNA in peripheral blood leukocytes (84.2% (266/316) vs. 44.7% (255/571), χ²=76.26, P<0.001) and the copies of EBV DNA (7.0×10⁷ (1.3×10⁷, 3.0×10⁸) vs. 3.1×10⁶ (1.6×10⁶, 6.1×10⁶) copies /L, Z=15.23, P<0.001) were higher than that of plasma. Conclusions: In immunocompetent pediatric cases diagnosed as EBV primary infection, cases with positive plasma EBV DNA were prone to have fever, hepatomegaly and (or) splenomegaly, and elevated transaminase than those with negative plasma viral DNA. The plasma EBV DNA usually turns negative within 28 days after initial diagnosis.Most cases with high viral load in plasma showed elevated aminotransferase.
Female ; Male ; Humans ; Child ; DNA, Viral ; Herpesvirus 4, Human ; Epstein-Barr Virus Infections ; Hepatomegaly ; Retrospective Studies ; Splenomegaly ; Fever ; Transaminases

Objective: To investigate the demographic characteristics and clinical influencing factors which associates with the occurrence probability of persistent or intermittent hypoviremia (LLV) in patients with chronic hepatitis B (CHB) treated with nucleos(t)ide analogues (NAs). Methods: A single-center retrospective analysis was performed on patients with CHB who received outpatient NAs therapy for≥48 ± 2 weeks. According to the serum hepatitis B virus (HBV) DNA load at 48±2 weeks treatment, the study groups were divided into LLV (HBV DNA < 20 IU/ml and < 2 000 IU/ml) and MVR group (sustained virological response, HBV DNA < 20 IU/ml). Demographic characteristics and clinical data at the start of NAs treatment (considered as baseline) were retrospectively collected for both patient groups. The differences in the reduction of HBV DNA load during treatment was compared between the two groups. Correlation and multivariate analysis were further conducted to analyze the associated factors influencing the LLV occurrence. Statistical analysis was performed using the independent samples t-test, c2 test, Spearman analysis, multivariate logistic regression analysis, or area under the receiver operating characteristic curve. Results: A total of 509 cases were enrolled, with 189 and 320 in the LLV and MVR groups, respectively. Compared to patients with MVR group at baseline: (1) the demographics characteristics of patients showed that LLV group was younger in age (39.1 years, P = 0.027), had a stronger family history (60.3%, P = 0.001), 61.9% received ETV treatment, and higher proportion of compensated cirrhosis (20.6%, P = 0.025) at baseline; (2) the serum virological characteristics of patients showed that LLV group had higher HBV DNA load, qHBsAg level, qHBeAg level, HBeAg positive rate, and the proportion of genotype C HBV infection but decreased HBV DNA during treatment (P < 0.001) at baseline; (3) the biochemical characteristics of patients showed that LLV group had lower serum ALT levels (P = 0.007) at baseline; (4) the noninvasive fibrosis markers of patients showed that LLV group were characterized by high aspartate aminotransferase platelet ratio index (APRI) (P = 0.02) and FIB-4 (P = 0.027) at baseline. HBV DNA, qHBsAg and qHBeAg were positively correlated with LLV occurrence (r = 0.559, 0.344, 0.435, respectively), while age and HBV DNA reduction were negatively correlated (r = -0.098, -0.876, respectively). Logistic regression analysis showed that ETV treatment history, high HBV DNA load at baseline, high qHBsAg level, high qHBeAg level, HBeAg positive, low ALT and HBV DNA level were independent risk factors for patients with CHB who developed LLV with NAs treatment. Multivariate prediction model had a good predictive value for LLV occurrence [AUC 0.922 (95%CI: 0.897 ~ 0.946)]. Conclusion: In this study, 37.1% of CHB patients treated with first-line NAs has LLV. The formation of LLV is influenced by various factors. HBeAg positivity, genotype C HBV infection, high baseline HBV DNA load, high qHBsAg level, high qHBeAg level, high APRI or FIB-4 value, low baseline ALT level, reduced HBV DNA during treatment, concomitant family history, metabolic liver disease history, and age < 40 years old are potential risk factors for developing LLV in patients with CHB during the therapeutic process.
Humans ; Adult ; Hepatitis B, Chronic/complications* ; Retrospective Studies ; Cross-Sectional Studies ; Hepatitis B e Antigens ; DNA, Viral ; Antiviral Agents/therapeutic use* ; Hepatitis B virus/genetics* ; Demography

BACKGROUND: Hepatitis B surface antigen (HBsAg) clearance is vital for a functional cure of hepatitis B virus (HBV) infection. However, the incidence and predictors of HBsAg seroclearance in patients co-infected with HBV and human immunodeficiency virus (HIV) remain largely unknown in Guangdong, China. METHODS: Between 2009 and 2019, patients co-infected with HBV/HIV undergoing antiretroviral therapy (ART) in Guangzhou Eighth People's Hospital affiliated to Guangzhou Medical University were retrospectively reviewed with the endpoint on December 31, 2020. The incidence and risk factors for HBsAg seroclearance were evaluated using Kaplan-Meier and multivariate Cox regression analyses. RESULTS: A total of 1550 HBV/HIV co-infected patients were included in the study, with the median age of 42 years and 86.0% (1333/1550) males. Further, 98.3% (1524/1550) received ART containing tenofovir disoproxil fumarate (TDF) plus lamivudine (3TC). HBV DNA was examined in 1283 cases at the last follow-up. Over the median 4.7 years of follow-up, 8.1% (126/1550) patients achieved HBsAg seroclearance, among whom 50.8% (64/126) obtained hepatitis B surface antibody, 28.1% (137/488) acquired hepatitis B e antigen seroconversion, and 95.9% (1231/1283) undetectable HBV DNA. Compared with patients who maintained HBsAg positive, cases achieving HBsAg seroclearance showed no differences in age, gender, CD4 + T cell count, alanine aminotransferase (ALT) level, or fibrosis status; however, they presented lower HBV DNA levels, lower HBsAg levels, and higher rates of HBV genotype B at the baseline. Multivariate analysis showed that baseline HBsAg <1500 cutoff index (COI) (adjusted hazard ratio [aHR], 2.74, 95% confidence interval [95% CI]: 1.48-5.09), ALT elevation >2 × upper limit of normal during the first six months after receiving ART (aHR, 2.96, 95% CI: 1.53-5.77), and HBV genotype B (aHR, 3.73, 95% CI: 1.46-9.59) were independent predictors for HBsAg seroclearance (all P <0.01). CONCLUSIONS Long-term TDF-containing ART has high anti-HBV efficacy including relatively high overall HBsAg seroclearance in HBV/HIV co-infected patients. Lower baseline HBsAg levels, HBV genotype B, and elevated ALT levels during the first six months of ART are potential predictors of HBsAg seroclearance.
Male ; Humans ; Adult ; Hepatitis B Surface Antigens ; Hepatitis B virus/genetics* ; HIV Infections/drug therapy* ; HIV ; DNA, Viral ; Incidence ; Coinfection/drug therapy* ; Retrospective Studies ; Tenofovir/therapeutic use* ; Lamivudine/therapeutic use* ; Hepatitis B, Chronic/drug therapy*