carbocyanines and Papillomavirus-Infections

Recently, nucleic acid amplification and detection techniques have progressed based on advances in in microfluidics, microelectronics, and optical systems. Nucleic acids amplification based point-of-care test (POCT) in resource-limited settings requires simple visual detection methods. Several biosensing methods including lateral flow immunoassays (LFIA) were previously used to visually detect nucleic acids. However, prolonged assay time, several washing steps, and a need for specific antibodies limited their use. Here we developed a novel, rapid method to visualize amplified nucleic acids with naked eyes in clinical samples. First, we optimized conditions based on separation using very low centrifugal force and a density medium to detect human papillomavirus (HPV)-16 DNA in cervical specimens. After DNA extraction, HPV16 PCR was performed with biotin-labeled forward primer and Cy3-labeled reverse primer. PCR amplicon was mixed with streptavidin-magnetic beads, introduced into the density medium. After two-minute centrifugation, the result was visually identified. This system showed identical results with commercial HPV real-time PCR for 30 clinical samples and could detect up to 10(2)copies/mL of HPV DNA without any optical instruments. This robust and sensitive visual detection system is suitable for non-specialist personnel and point-of-care diagnosis in low-resource settings.

Topics: Biosensing Techniques; Carbocyanines; Centrifugation, Density Gradient; Cervix Uteri; DNA, Viral; Female; Human papillomavirus 16; Humans; Magnets; Optical Imaging; Papillomavirus Infections; Point-of-Care Systems; Polymerase Chain Reaction

Persistent cervical high-risk human papillomavirus (HPV) infection is correlated with an increased risk of developing a high-grade cervical intraepithelial lesion. A two-step method was developed for detection and genotyping of high-risk HPV. DNA was firstly amplified by asymmetrical PCR in the presence of Cy3-labelled primers and dUTP. Labelled DNA was then genotyped using DNA microarray hybridization. The current study evaluated the technical efficacy of laboratory-designed HPV DNA microarrays for high-risk HPV genotyping on 57 malignant and non-malignant cervical smears. The approach was evaluated for a broad range of cytological samples: high-grade squamous intraepithelial lesions (HSIL), low-grade squamous intraepithelial lesions (LSIL) and atypical squamous cells of high-grade (ASC-H). High-risk HPV was also detected in six atypical squamous cells of undetermined significance (ASC-US) samples; among them only one cervical specimen was found uninfected, associated with no histological lesion. The HPV oligonucleotide DNA microarray genotyping detected 36 infections with a single high-risk HPV type and 5 multiple infections with several high-risk types. Taken together, these results demonstrate the sensitivity and specificity of the HPV DNA microarray approach. This approach could improve clinical management of patients with cervical cytological abnormalities.

Topics: Base Sequence; Carbocyanines; Deoxyuracil Nucleotides; DNA Primers; DNA, Viral; Genotype; HeLa Cells; Humans; Molecular Sequence Data; Oligonucleotide Array Sequence Analysis; Papillomaviridae; Papillomavirus Infections; Polymerase Chain Reaction; Sensitivity and Specificity; Sequence Alignment; Vaginal Smears