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

BACKGROUND

The COVID-19 pandemic caused by SARS-CoV-2 significantly strained healthcare systems in the Philippines, highlighting the critical importance of reliable molecular diagnostics and genomic surveillance. Although vaccination efforts and public health measures mitigated disease impact, the continued emergence of viral variants underscores the need for sustainable local surveillance strategies. Strengthening in-country capacity through the development of in silico–designed primers and cost-effective sequencing approaches can enhance rapid variant detection and improve preparedness for future emerging infectious diseases.

OBJECTIVE

This paper offers a method in detecting the SARS-CoV-2 virus and its variants. A direct PCR product sequencing surveillance or DPPSS offers a new possibility of detecting emerging disease by using PCR products and using it as templates in determining the base sequence.

METHODOLOGY

A total of 20 random positive samples for SARS-COV-2 from March 2022 sample pool in Metro Manila, Philippines was used in this study. The RNA was extracted using Purelink™ RNA Mini Kit, quantified with NanoDrop, and subjected to one-step RT-PCR. An in-house designed in silico primers were used in this study by using thermodynamic parameters to optimize specificity and amplification efficiency, considering GC contents, balanced Tm, minimal secondary structures and cross-dimers and in silico validation via Basic Local Alignment Search Tool (BLAST) against reference databases.

Amplicons were analyzed through gel electrophoresis, sequenced, and analyzed using BioEdit software. A nucleotide BLAST search identified COVID-19 variants, confirmed using Cov-Lineages website.

RESULTS

In silico designed primers (S1, S2, E/M, Orf1ab) collectively exhibited 100% sensitivity in detecting SARS-CoV2 in nasopharyngeal swab samples. Individual primer sensitivities varied, with Orf1ab at 58.82% and E/M at 90.91%. Our analysis revealed the prevalence of Omicron sublineage BA.2 in the Philippines, aligning with local data showing more BA.2 cases than the global predominance of BA.1.

CONCLUSION

Combined in silico primers (S1, S2, E/M, ORF1ab) accurately detect SARS-COV-2 and its variants. This method provides a valuable diagnostic and surveillance tool for public health management.

Covid-19 ; Polymerase Chain Reaction ; Molecular Diagnostic Techniques

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

BACKGROUND AND OBJECTIVES

Cell lines serve as invaluable tools in studying lung cancer biology and developing new therapies to combat the disease. However, commercially available cell lines are typically of Caucasian origin and may be less representative of the local genetic background. To address this, our lab previously immortalized cells from pleural fluid of a Filipino non-small cell lung cancer (NSCLC) patient via CDK4 transduction. Copy number variations (CNVs) are a type of genetic variation which may affect physiology and disease by disrupting gene function or altering gene expression, and in cancer, these may be associated with patient outcomes. CNV profiling can be valuable for understanding the biology of our immortalized cells and identifying genes that could serve as potential targets for diagnostic, prognostic, and therapeutic interventions. This study aimed to characterize previously immortalized NSCLC-derived cells, GL01, in comparison with an established lung adenocarcinoma (LUAD) cell line, A549, through whole-genome microarray-based copy number profiling.

METHODS

DNA was extracted from GL01 and A549 cells using a commercially-available silica-based DNA extraction kit. DNA extracts were quantified and normalized for microarray analysis. Whole-genome copy number profiling was done using the OncoScan CNV Plus Assay following the manufacturer’s protocols, and data was analyzed using the Chromosome Analysis Suite software. Functional analysis of genes identified to be involved in copy number aberrations was done using the PANTHER Classification System.

RESULTS

Copy number aberrations span 1,592,737,105 bp in GL01 and 1,715,708,552 bp in A549, with a high degree of concordance between the two. Large-scale and focal copy number aberrations previously identified to be recurrent in various LUAD cohorts were present in both GL01 and A549. Focal copy number aberrations associated with previously described lung cancer-related genes involve the PDE4D gene in GL01 and the SKIL and CDKN2A/CDKN2B genes in both GL01 and A549. PANTHER Pathway analysis of genes positively correlated with mRNA expression showed that the ubiquitin proteasome pathway was significantly overrepresented in both GL01 (FDR p = 0.000074) and A549 (FDR p = 0.000075), with 20 genes involved. Additionally, the KRAS:p.G12C/S:c.34G>T/A somatic mutation variant was detected in both GL01 and A549.

CONCLUSION

This study provides a method for identifying potentially clinically-relevant genes associated with a sample’s copy number aberrations and the pathways they represent, providing personalized mechanistic, prognostic, and therapeutic insights into the cancer biology of our cells.

Human ; Carcinoma, Non-small-cell Lung ; Adenocarcinoma Of Lung

Background and Objectives: Cell lines serve as invaluable tools in studying lung cancer biology and developing new therapies to combat the disease. However, commercially available cell lines are typically of Caucasian origin and may be less representative of the local genetic background. To address this, our lab previously immortalized cells from pleural fluid of a Filipino non-small cell lung cancer (NSCLC) patient via CDK4 transduction. Copy number variations (CNVs) are a type of genetic variation which may affect physiology and disease by disrupting gene function or altering gene expression, and in cancer, these may be associated with patient outcomes. CNV profiling can be valuable for understanding the biology of our immortalized cells and identifying genes that could serve as potential targets for diagnostic, prognostic, and therapeutic interventions. This study aimed to characterize previously immortalized NSCLC-derived cells, GL01, in comparison with an established lung adenocarcinoma (LUAD) cell line, A549, through whole-genome microarray-based copy number profiling. Methods: DNA was extracted from GL01 and A549 cells using a commercially-available silica-based DNA extraction kit. DNA extracts were quantified and normalized for microarray analysis. Whole-genome copy number profiling was done using the OncoScan CNV Plus Assay following the manufacturer’s protocols, and data was analyzed using the Chromosome Analysis Suite software. Functional analysis of genes identified to be involved in copy number aberrations was done using the PANTHER Classification System. Results: Copy number aberrations span 1,592,737,105 bp in GL01 and 1,715,708,552 bp in A549, with a high degree of concordance between the two. Largescale and focal copy number aberrations previously identified to be recurrent in various LUAD cohorts were present in both GL01 and A549. Focal copy number aberrations associated with previously described lung cancer-related genes involve the PDE4D gene in GL01 and the SKIL and CDKN2A/CDKN2B genes in both GL01 and A549. PANTHER Pathway analysis of genes positively correlated with mRNA expression showed that the ubiquitin proteasome pathway was significantly overrepresented in both GL01 (FDR p = 0.000074) and A549 (FDR p = 0.000075), with 20 genes involved. Additionally, the KRAS:p.G12C/S:c.34G>T/A somatic mutation variant was detected in both GL01 and A549. Conclusion This study provides a method for identifying potentially clinically-relevant genes associated with a sample’s copy number aberrations and the pathways they represent, providing personalized mechanistic, prognostic, and therapeutic insights into the cancer biology of our cells.
carcinoma, non-small cell lung ; adenocarcinoma of lung