Use of multiple displacement amplification in the investigation of human papillomavirus physical status

Real-time PCR detection of human herpesvirus 1-5 in patients lacking clinical signs of a viral CNS infection

Background

Infections of the central nervous system (CNS) with herpes- or enterovirus can be self-limiting and benign, but occasionally result in severe and fatal disease. The polymerase chain reaction (PCR) has revolutionized the diagnostics of viral pathogens, and by multiple displacement amplification (MDA) prior to real-time PCR the sensitivity might be further enhanced. The aim of this study was to investigate if herpes- or enterovirus can be detected in cerebrospinal fluid (CSF) from patients without symptoms.

Methods

Cerebrospinal fluid (CSF) samples from 373 patients lacking typical symptoms of viral CNS infection were analysed by real-time PCR targeting herpesviruses or enteroviruses with or without prior MDA.

Results

In total, virus was detected in 17 patients (4%). Epstein-Barr virus (EBV) was most commonly detected, in general from patients with other conditions (e.g. infections, cerebral hemorrhage). MDA satisfactorily amplified viral DNA in the absence of human nucleic acids, but showed poor amplification capacity for viral DNA in CSF samples, and did not increase the sensitivity for herpes virus-detection with our methodology.

Conclusions

Viral pathogens are rarely detected in CSF from patients without signs of CNS infection, supporting the view that real-time PCR is a highly specific method to detect symptomatic CNS-infection caused by these viruses. However, EBV may be subclinically reactivated due to other pathological conditions in the CNS.

The HPV transcriptome in HPV16 positive cell lines

BACKGROUND

Infections with high-risk human papillomaviruses (HPV), mainly HPV type 16, can cause malignant transformation of the human cervical epithelium and cervical cancer (CxCa). Very little is known about the quantitative expression of the various HPV16 transcripts in frequently used cervical cancer cell lines.

METHODS

We have quantitatively analysed the viral transcriptome in the HPV16-transformed cell lines SiHa, CaSki, MRI-H196, MRI-H186, HPK-IA and C3. We used a nucleic acid sequence-based amplification (NASBA)-Luminex hybridisation assay quantifying spliced and unspliced HPV16 transcripts.

RESULTS

The cell lines differed in their qualitative and quantitative expression of viral transcripts depending on the physical HPV genome status. In SiHa, we found no transcripts containing the splice acceptor at nucleotide 3358 or downstream sequences. In CaSki cells virtually all viral transcripts were detected but with a reduced quantity of late transcripts. We further found that the tumorigenic phenotype of late passage HPK-IA cells may not be mediated through changes in HPV expression. In MRI-H186, HPK-IA and C3 cells very high levels of full-length early transcripts ending at the early polyadenylation signal were found. MRI-H196 expressed L1 full-length (fl) but no E5 fl RNA suggesting the presence of integrated HPV16 genomes with a disrupted E2 region and rearranged L1 DNA sequence.

CONCLUSION

Quantitative expression changes of HPV16 transcript markers correlate with the physical state of the HPV genome in HPV16 positive cervical cancer cell lines.

Evidence of HPV16 integration in low- and high-grade cervical lesions that regress demonstrated by multiple displacement amplification and Southern blot hybridisation

The prevalence and significance of human papillomavirus (HPV) integration among different grades of cervical lesions is uncertain. In this study, HPV physical status was examined by the combination of multiple displacement amplification (MDA) with Southern blot hybridisation (SBH). DNA extracts from 95 cervical cytology samples (NILM, ASC-US, LSIL, ASC-H, HSIL) were subject to whole genome amplification by MDA followed by SBH with [alpha-(32)P]-labelled HPV probes. Mixed HPV16 episomal/integrant sequences were detected in three ASC-US patients (two diagnosed with benign changes and one with cervical intraepithelial neoplasia (CIN)2/3 after biopsy follow-up), one ASC-H patient with CIN2/3 histological diagnosis, and one HSIL patient with benign changes. Additional follow-up cytological data available for three of these patients demonstrated series of lesion-free samples. The data support the view that integration can occur in low-grade lesions and that lesions with mixed episomal/integrant HPV can regress.