PCR in situ hybridisation detection of HPV 16 in fixed CaSki and fixed SiHa cell lines

One step DNA amplification of mammalian cells in picoliter microwell arrays

One-step PCR of a single cell in a picoliter microwell array was developed and applied to detect a target with the sensitivity of a single copy.

Saliva-Based Screening of High-Risk Human Papillomavirus Strains: Detection in Female Indonesian and Thai Dental Students

BACKGROUND

Currently it is believed that human papillomaviruses (HPV) are associated with the development of some oral/oropharyngeal cancers. It has been suggested that these viruses influence carcinogenesis in both smokers and non-smokers. Data on the prevalence of HPV in healthy adults are thus needed to estimate the risk of oral/oropharyngeal cancer. The aim of this study was to assess the prevalence of oral HPV in healthy female adults in Indonesia and Thailand.

MATERIALS AND METHODS

Healthy female students from the Faculties of Dentistry of Universitas Indonesia and Chiang Mai University were asked to participate in this pilot study. DNA was extracted from saliva specimens and screened for HPV16 and HPV18 using PCR.

RESULTS

The age, marital status and sexual experience of the subjects between the two countries were not significantly different. Eight (4%) and 4 (2%) samples were positive for HPV16 and HPV18, respectively. Fisher's Exact test found a significant difference between HPV16 positivity in subjects who were married and had sexual intercourse but not for HPV18.

CONCLUSIONS

This study successfully detected presence of HPV16 and HPV18 DNA in a number of saliva samples from female dental school students. Marital status, experience of sexual intercourse and safe sexual practice are related to the possibility of finding HPV DNA finding in saliva. Dentists, physicians and other health care professionals may gain significant value from the findings of this study, which provide an understanding of the nature of HPV infection and its risk to patient health and disease.

In situ analysis of intrahepatic virological events in chronic hepatitis B virus infection

Persistent hepatitis B virus (HBV) infection is established by the formation of an intranuclear pool of covalently closed circular DNA (cccDNA) in the liver. Very little is known about the intrahepatic distribution of HBV cccDNA in infected patients, particularly at the single-cell level. Here, we established a highly sensitive and specific ISH assay for the detection of HBV RNA, DNA, and cccDNA. The specificity of our cccDNA probe set was confirmed by its strict intranuclear signal and by a series of Southern blot analyses. Use of our in situ assay in conjunction with IHC or immunofluorescence uncovered a surprisingly mosaic distribution of viral antigens and nucleic acids. Most strikingly, a mutually exclusive pattern was found between HBV surface antigen-positive (HBsA-positive) and HBV DNA- and cccDNA-positive cells. A longitudinal observation of patients over a 1-year period of adeforvir therapy confirmed the persistence of a nuclear reservoir of viral DNA, although cytoplasmic DNA was effectively depleted in these individuals. In conclusion, our method for detecting viral nucleic acids, including cccDNA, with single-cell resolution provides a means for monitoring intrahepatic virological events in chronic HBV infection. More important, our observations unravel the complexity of the HBV life cycle in vivo.

Effects of cellular differentiation, chromosomal integration and 5-aza-2'-deoxycytidine treatment on human papillomavirus-16 DNA methylation in cultured cell lines

Human papillomavirus-16 (HPV-16) genomes in cell culture and in situ are affected by polymorphic methylation patterns, which can repress the viral transcription. In order to understand some of the underlying mechanisms, we investigated changes of the methylation of HPV-16 DNA in cell cultures in response to cellular differentiation, to recombination with cellular DNA, and to an inhibitor of methylation. Undifferentiated W12E cells, derived from a precancerous lesion, contained extrachromosomal HPV-16 DNA with a sporadically methylated enhancer-promoter segment. Upon W12E cell differentiation, the viral DNA was demethylated, suggesting a link between differentiation and the epigenetic state of HPV-16 DNA. The viral genomes present in two W12I clones, in which individual copies of the HPV-16 genome have integrated into cellular DNA (type 1 integrants), were unmethylated, akin to that seen in the cervical carcinoma cell line SiHa (also a type 1 integrant). This finding is consistent with hypomethylation being necessary for continued viral gene expression. In contrast, two of three type 2 integrant W12I clones, containing concatemers of HPV-16 genomes integrated into the cellular DNA contained hypermethylated viral DNA, as observed in the cervical carcinoma cell line CaSki (also a type 2 integrant). A third, type 2, W12I clone, interestingly with fewer copies of the viral genome, contained unmethylated HPV-16 genomes. Epithelial differentiation of W12I clones did not lead to demethylation of chromosomally integrated viral genomes as was seen for extrachromosomal HPV-16 DNA in W12E clones. Hypomethylation of CaSki cells in the presence of the DNA methylation inhibitor 5-aza-2'-deoxycytidine reduced the cellular viability, possibly as a consequence of toxic effects of an excess of HPV-16 gene products. Our data support a model wherein (i) the DNA methylation state of extrachromosomal HPV16 replicons and epithelial differentiation are inversely coupled during the viral life cycle, (ii) integration of the viral genome into the host chromosome events leads to an alteration in methylation patterns on the viral genome that is dependent upon the type of integration event and possibly copy number, and (iii) integration universally results in the viral DNA becoming refractory to changes in methylation state upon cellular differentiation that are observed with extrachromosomal HPV-16 genomes.

GAP-43 mRNA detection by in situ hybridization, direct and indirect in situ RT-PCR in hippocampal and cerebellar tissue sections of adult rat brain

The growth-associated protein GAP-43 is a presynaptic membrane phosphoprotein that is expressed at high levels during development and axonal growth. To evaluate the cellular distribution of GAP-43 mRNA in the hippocampus and cerebellum of adult rats we applied in situ hybridization (ISH) as well as direct and indirect in situ RT-PCR using biotin as a reporter molecule. ISH resulted in a positive signal in most cerebellar granular cells and in 30% of hippocampal CA3 neurons. Direct in situ RT-PCR yielded cells with strong signals in every region investigated, with elevated background levels most likely related to incorporation of labeled nucleotides into non-specific amplicons through internal priming and DNA repair activity. Indirect in situ RT-PCR turned out to be the best approach for detecting GAP-43 mRNA positive cells. Cerebellar cells exhibiting a positive signal for GAP-43 mRNA were of the granular cell type (98%). Hippocampal neurons with a positive reaction for GAP-43 mRNA included all the neuron groups analyzed, namely CA1 (99%) and CA3 pyramidal cells (94%) and dentate gyrus granule cells (92%). Dentate gyrus granule cells have not tested positive for GAP-43 mRNA detection by molecular morphology analysis. These data show that in normal rats GAP-43 mRNA is present in different cell populations of hippocampal formation, supporting the role of this protein in the ongoing processes of synaptic plasticity.

Epstein-Barr virus-associated lymphoepithelioma-like carcinoma of the esophagus

Epstein-Barr virus (EBV)-associated lymphoepithelioma-like carcinoma (LELC) rarely occurs in the esophagus. We report a case of such tumor arising in the esophagus of a 64-year-old Taiwanese woman. No tumors were detected outside the esophagus including nasopharynx by thorough clinical studies. She underwent subtotal esophagectomy. Light microscopy disclosed a poorly differentiated carcinoma morphologically reminiscent of nasopharyngeal undifferentiated carcinoma (lymphoepithelioma). Immunohistochemical stain for latent membrane protein-1 showed positivity on the tumor cells. The infiltrating lymphocytes were chiefly composed of CD8-positive cytotoxic T cells. EBV DNA was demonstrated by both nested polymerase chain reaction (PCR) in the main tumor and metastatic lymph node, and localization in the tumor cells by in situ PCR in situ hybridization (ISH). However, the result of EBV-encoded small RNA-1 ISH was negative. Our case suggests that LELC of the esophagus may be associated with EBV in the endemic area. Due to its distinct histological features, the association with EBV, and possible prognostic implication, LELC of the esophagus should be precisely diagnosed and discerned from the usual poorly differentiated carcinoma.

Detection of Trypanosoma cruzi DNA within murine cardiac tissue sections by in situ polymerase chain reaction

The use of in situ techniques to detect DNA and RNA sequences has proven to be an invaluable technique with paraffin-embedded tissue. Advances in non-radioactive detection systems have further made these procedures shorter and safer. We report the detection of Trypanosoma cruzi, the causative agent of Chagas disease, via indirect and direct in situ polymerace chain reaction within paraffin-embedded murine cardiac tissue sections. The presence of three T. cruzi specific DNA sequences were evaluated: a 122 base pair (bp) sequence localized within the minicircle network, a 188 bp satellite nuclear repetitive sequence and a 177 bp sequence that codes for a flagellar protein. In situ hybridization alone was sensitive enough to detect all three T. cruzi specific DNA sequences.

Detection of Epstein-Barr virus genome within thymic epithelial tumours in Taiwanese patients by nested PCR, PCR in situ hybridization, and RNA in situ hybridization

Epstein-Barr virus (EBV) is known to be associated with a variety of tumours, including Burkitt's lymphoma, nasopharyngeal carcinoma, and some carcinomas of other organs with similar lymphoepithelioma-like features. The association between EBV and thymic epithelial tumours is inconclusive, as reports in this regard are not entirely consistent and the methods employed are of different sensitivity and specificity. This study examined 78 thymomas and 21 thymic carcinomas in Taiwanese patients, to detect the viral genome at both DNA and RNA levels. The tissue blocks were first screened by nested polymerase chain reaction (PCR) targeting on the first tandem internal repeats. The positive cases were further submitted for viral localization by in situ PCR insitu hybridization (ISH) and Epstein-Barr-encoded RNA-1 (EBER-1) ISH. None of the thymomas showed a detectable EBV genome. Eight thymic carcinomas were positive for EBV by nested PCR, of which six displayed nuclear signals within the tumour cells by in situ PCR ISH and/or RNA ISH, one displayed signals within the lymphocytes, and one showed no discernible in situ signals. Most of them exhibited a lymphoepithelioma-like morphology. These results show that nested PCR is a sensitive method for screening the EBV genome in thymic epithelial tumours. In situ PCR ISH is reliable for localization of the virus, in addition to EBER-1 RNA ISH. Thymomas are not related to EBV, even in this endemic area. Thymic carcinomas, especially the lymphoepithelioma-like thymic carcinomas, are more often associated with the virus.

Risk of oral cancer associated with human papillomavirus infection, betel quid chewing, and cigarette smoking in Taiwan--an integrated molecular and epidemiological study of 58 cases

BACKGROUND

The association between oral squamous cell carcinoma (OSCC) and human papillomavirus (HPV) 6, 11, 16 and 18 is uncertain. Past reports varied in the methodology and results. We conducted this study using in situ PCR in situ hybridization (ISH) assay which was considered as the most sensitive method for detection of viral DNA. We undertook an epidemiologic survey about the history of betel quid chewing and cigarette smoking, since these habits are common in Taiwan.

METHODS

In situ PCR ISH was performed on the tumor specimens from 29 patients with OSCC and the oral mucosal specimens from 29 patients without OSCC. Their betel quid chewing and cigarette smoking histories were also reviewed.

RESULTS

HPV16, HPV18, betel quid chewing and cigarette smoking were statistically significant risk factors in univariate analysis. HPV6 and 11 were not. Multivariate analysis showed that HPV16 infection (adjusted Odds ratio = 11.20) and betel quid chewing (adjusted Odds ratio = 17.06) remained to be independent factors for OSCC.

CONCLUSIONS

Our results showed that HPV16 and betel quid chewing were two major risk factors for OSCC in Taiwan, indicating that they act through different mechanisms in the pathogenesis of OSCC.

Correlation of human papillomavirus 16 and 18 with cervical neoplasia in histological typing and clinical stage in Taiwan: an in-situ polymerase chain reaction approach

BACKGROUND AND OBJECTIVES

In situ polymerase chain reaction (ISPCR) promises to considerably enhance our ability to detect a few copies of target nucleic acid sequences in fixed tissues and cells. The aim of this study was to investigate cervical carcinoma to determine the human papillomavirus (HPV) types on paraffin-embedded tissue sections by ISPCR and standard in situ hybridization. The results will correlate the morphological characteristics of lesions with viral typing results.

METHODS

This study examined prevalence of HPV 16 and 18 DNA in biopsies from 85 cervical cancer patients by ISPCR, employing HPV 16, 18 consensus primers. There are 45 patients with squamous cell carcinomas, 13 with adenocarcinoma, 2 with adenosquamous carcinomas, 3 with small cell carcinomas, and 22 carcinoma in situ. The relation between the types of HPV detected, tumor type, and clinical stage were analyzed.

RESULTS

Fifty-two of 85 biopsies were HPV 16- or 18-positive, HPV 16 being the most prevalent type. Squamous cell carcinoma had a high prevalence of HPV 16 and adenocarcinoma had a high prevalence of HPV 18. HPV 18 was the predominant type among high clinical stage (III-IV) cases while HPV 16 and mixed HPV 16 with HPV18 were significantly correlated with low clinical stage (0-I-II).

CONCLUSION

Our results indicate that certain malignant cervical tumor phenotypes and stages correlate with specific HPV type, and that ISPCR is a sensitive and fast method to detect HPV in these patients.

Establishment of a new cell line, OKT1, from small cell carcinoma secreting ectopic ACTH of the uterine cervix

OBJECTIVE

Small cell carcinoma of the uterine cervix is rare and represents a unique entity among gynecological tumors. It sometimes demonstrates neuroendocrine differentiation, including adrenocorticotropin (ACTH) secretion. In this study, we established a new cell line, OKT1, from a case of carcinoma secreting ectopic ACTH without Cushing's syndrome and determined the character of the cell line.

METHODS

OKT1 was established from OKT tumor cells, derived from a biopsy specimen of small cell cervical carcinoma, and serially heterotransplanted into nude mice. To characterize OKT1, the cell morphology, growth properties, immunohistochemical properties, hormone- and tumor-associated antigen secretion, tumorigenic potential, DNA profile, and chromosomal alteration were studied.

RESULTS

The population doubling time of OKT1 was approximately 27 h. The cytological properties of OKT1, including DNA ploidy pattern, were similar to those of the primary tumor. Neuroendocrine differentiation was shown in the OKT1 cells by the positive immunocytochemical staining of neuron-specific enolase (NSE) and the presence of NSE and ACTH in the culture media. The xenograft of 1 x 10(8) OKT1 cells into nude mice yielded tumor mass. Furthermore, OKT1 demonstrated HPV type 18 and absence of a p53 gene mutation from exons 5 through 8.

CONCLUSION

To our knowledge, OKT1 is the first cell line established from small cell cervical carcinoma with ACTH secretion.

Detection of low copy numbers of HPV DNA by fluorescent in situ hybridization combined with confocal microscopy as an alternative to in situ polymerase chain reaction

In genital lesions infected by human papillomavirus (HPV), histological criteria and HPV DNA typing are of prognostic value. Therefore, non-radioactive methods such as in situ hybridization are used extensively since they preserve the histological organization of the tissue, and allow the detection and characterization of HPV DNA. However, the sensitivity of these methods is often limited to detection of low copy numbers of HPV DNA in isolated cells or in tissue sections, and therefore alternative techniques have been explored. In the present study, 1-2 copies of HPV DNA were visualized in SiHa cells either by in situ amplification of nucleic acid sequences with the polymerase chain reaction (PCR) or by fluorescent in situ hybridization (FISH) associated with observation by laser scanning confocal microscopy (LSCM). The latter procedure was evaluated for use on histological tissue sections to identify low copy numbers of HPV DNA. Genital lesions which were negative by enzymatic in situ hybridization and FISH but histologically suspected of HPV infection were investigated, and intense signals were obtained both with in situ PCR and with the combined use of FISH and LSCM. Therefore, the combination of FISH with LSCM examination may be as valuable as in situ PCR to detect viral genes present in small amounts in isolated cells and in tissue sections.

In situ hybridization detection of low copy nucleic acid sequences using catalyzed reporter deposition and its usefulness in clinical human papillomavirus typing

In situ hybridization (ISH) detection of low copy DNA and RNA sequences using nonisotopic probes has been difficult in the past because of a lack of sensitivity. Several techniques, such as ISH with radioisotopic-labeled probes, in situ polymerase chain reaction, in situ reverse transcription polymerase chain reaction, self-sustained sequence replication, and chemiluminescence, have allowed increased sensitivity but have required specialized and often expensive equipment, lengthy protocols, and in the case of radioactive probes, there has been an associated increased health risk. Catalyzed reporter deposition (CARD) combined with ISH (CARD-ISH) increases the signal-generating potential of labeled hybridized probes and allows the detection of low copy sequences of nucleic acids in formalin-fixed, paraffin-embedded tissue sections. To determine the sensitivity of CARD-ISH to detect nucleic acids in routinely processed specimens, we analyzed the detection of HPV 16 and 18 infection in formalin-fixed, paraffin-embedded sections of cultured cell lines, including CaSki cells with 400-600 copies of HPV 16, HeLa 229 cells with 10-50 copies of HPV 18, and SiHa cells with 1-2 copies of HPV 16 using a conventional ISH method and by CARD-ISH. In addition, 20 cases of clinical specimens previously analyzed for HPV 6, 11, 16, 18, 31, 33, and 51 with the Enzo PathoGene kit (Enzo Diagnostics, Inc., Farmingdale, NY, U.S.A.) were reexamined with the CARD-ISH method. The CARD-ISH system detected one to two copies of HPV 16 in the SiHa cells whereas the conventional ISH method did not. Both methods detected HPV 16 and 18 in CaSki and HeLa 229 cells, respectively. Three clinical cases that were previously negative and two weakly positive cases of HPV infection were all strongly positive with the CARD-ISH system, a 25% increase in the detection of positive cases by CARD-ISH. We also showed for the first time that a cocktail of six biotinylated oligonucleotide probes was capable of detecting one to two copies of HPV 16 in SiHa cells. These results show that the CARD-ISH method increases the sensitivity of nonisotopic ISH to the level of detecting one to two copies of HPV DNA in formalin-fixed, paraffin-embedded tissue sections using biotinylated cDNA or oligonucleotide probes.

Human papillomavirus and mixed epithelial tumors of the endometrium

Strong epidemiological evidence links human papilloma viruses (HPV) with the development of cervical intraepithelial neoplasia (CIN) and invasive cancers of the uterine cervix. The localization of HPV DNA sequences high up in the female genital tract (in benign and malignant lesions) is not that uncommon, but its precise significance is uncertain. In particular, the detection of HPV DNA sequences by polymerase chain reaction (PCR) needs careful interpretation, because the source of the amplicon may emanate from tumor cells, direct contamination from the cervix, or possibly from extratumoral sites in the endometrium. We have previously reported the identification of koilocyte-like changes in the squamous epithelium of some endometrial adenoacanthomas. Adenoacanthomas (adenocarcinoma with squamous metaplasia) are mixed epithelial tumors arising in the endometrium composed of malignant glandular areas admixed with benign metaplastic squamous epithelium. The rarer adenosquamous carcinoma containing both malignant glandular and squamous areas is also described. The origin of benign/malignant squamous epithelial islands in endometrial tumors has been the subject of speculation, with some investigators considering an origin from metaplastic glandular endometrial cells. In this study, we examined 10 normal endometrial samples, 20 adenocarcinomas, 41 adenocarcinomas with squamous metaplasia, and two adenosquamous carcinomas, (including control cervical material where possible) for the presence of HPV DNA sequences using nonisotopic in situ hybridization (NISH), type-specific HPV PCR, general primer PCR (to detect sequenced and unsequenced HPVs), and PCR in situ hybridization (PCR-ISH). We did not identify HPV DNA sequences in normal endometrial tissue. In adenocarcinomas (endometrioid type), HPV was only identified in 2 of 20 cases by PCR, both of which were HPV 11 positive. We were unsuccessful in identifying HPV in endometrial carcinomas by NISH or by PCR-ISH, raising the possibility of contamination from the cervix in the two positive cases. In adenoacanthomas, a low-risk HPV type (HPV 6) was found in 19 of 41 cases. NISH signals were intranuclear in location in squamous regions of adenoacanthomas. Additional positive nuclei were uncovered using PCR-ISH, which increases the sensitivity of standard NISH detection. HPV DNA sequences were located in some malignant endometrial glandular epithelial cells, but this accounted for a minority of samples. HPV DNA sequences were not detected in extraepithelial sites. Mixed infection by two different HPV types was identified in two cases. Most cases showed similar HPV types in cervical and endometrial lesions, although discordant cases were uncovered. In adenosquamous carcinomas, one case showed mixed infection with HPV 6 and 33 by PCR. The apparent segregation of low-risk HPV type (HPV 6) with benign squamous metaplastic epithelium in adenocarcinoma with squamous metaplasia, and high-risk type (HPV 33) with malignant squamous epithelium in adenosquamous carcinoma, raises important questions in relation to the role of HPVs in mixed epithelial tumors of the endometrium and their interplay in the pathogenesis of squamous metaplasia at extracervical sites.

A novel grid polymerase chain reaction (G-PCR) approach at ultrastructural level to detect target DNA in cell cultures and tissues

A novel grid polymerase chain reaction (G-PCR) method has been developed to be used at the ultrastructural level and with a high degree of resolution. Samples applied to test the method were fresh cell lines (CaSki, SiHa) and HPV-16 DNA-containing tissues rescued from routine paraffin blocks. The specimens were embedded in Epon-Araldite and/or hydrophilic-resin LRWhite. Ultrathin sections mounted on grids were subjected to G-PCR using an HPV-16-specific primer set. The amplified products were identified by auro-immunohistochemical labelling of the biotinylated nucleotide. The results indicated successful amplification of target DNA in both cell and tissue samples, being confined to the intranuclear region. The negative controls [HeLa cells, isolated mammary carcinoma cell cultures (MCF 7, and T47-D) (ATCC) (U.S.A.), normal thyroid tissue and steroid-producing tumour tissue] failed to exhibit any amplification of the target DNA sequences. The sensitivity of the G-PCR system was evaluated by performing a parallel in situ hybridization (ISH) of serial sections. The signals obtained from G-PCR were more intense than those of ISH and more informative as to the precise subcellular localization of amplicons.

Genotypic mapping of HPV and assessment of EBV prevalence in endocervical lesions

AIMS

To examine the prevalence of human papillomavirus (HPV) and Epstein-Barr virus (EBV) in low grade glandular intraepithelial lesions of the cervix, adenocarcinoma with high grade glandular intraepithelial lesions combined, and adenocarcinomas; and to perform a genotyping mapping analysis of endocervical carcinomas to determine the extent of HPV infections in such lesions.

MATERIAL

Archival paraffin wax embeded material from the files of the departments of pathology, National Maternity Hospital, Dublin, and University College Cork, Ireland.

METHODS

HPV prevalence was examined using type specific HPV PCR, general primer HPV PCR (pan HPV screen), nonisotopic in situ hybridisation (NISH), and PCR in situ hybridisation (PCR-ISH). In situ hybridisation was performed using fluorescein labelled oligonucleotide cocktail for eber transcripts of EBV. Genotypic analysis was performed, in all cases where possible, using a grid system.

RESULTS

HPV 16 and 18 were predominantly identified in low grade glandular intraepithelial lesions, high grade glandular intraepithelial lesions, and adenocarcinomas, with HPV prevalence increasing with grade of dysplasia. EBV was only identified in subepithelial lymphocytes in a minority of cases. No link could be shown between HPV and EBV in endocervical lesions. HPV infection was not clonal in endocervical cancer and coexistent adjacent cervical intraepithelial neoplasia, where present, tended to show a similar HPV type.

CONCLUSIONS

The restriction of HPV types 16 and 18 to endocervical lesions suggests that their effect is restricted and specific to endocervical mucosa, but the mechanism of interaction is currently unknown.

Detection of proviral DNA of bovine immunodeficiency virus in bovine tissues by polymerase chain reaction (PCR) and PCR in situ hybridization

In this study, experiments were designed to investigate the distribution of bovine immunodeficiency virus (BIV) proviral DNA in the tissues and cells of infected calves by solution-phase polymerase chain reaction (SP-PCR) and PCR in situ hybridization (PCR-ISH). Total DNA samples extracted from tissues of 10 BIV-infected and 5 uninfected calves were amplified by SP-PCR with the primers directed to the BIV conserved pol gene segment. The identity of the SP-PCR product was confirmed by Southern hybridization with a BIV pol gene cDNA probe. SP-PCR results demonstrated that BIV proviral DNA was present predominantly in neural tissues and some lymphoid tissues in BIV-infected calves. It also was detected frequently in other tissues including lung, heart, esophagus, and pancreas. Further investigation on cell location of BIV proviral DNA was performed by in situ amplification of DNA on formalin-fixed tissue sections. The amplified DNA was subjected to in situ hybridization with an internal biotinylated probe and detected with streptavidin-gold followed by silver enhancement. Specific BIV proviral DNA signals were observed in neurons, microglial cells, lymphocytes, septal macrophages, smooth muscle cells, and endothelial cells. On the basis of these results, we conclude that BIV replicates in a variety of bovine tissues in vivo and has a broad cell tropism.

A comparison of RT-PCR, in-situ hybridisation and in-situ RT-PCR for the detection of rhinovirus infection in paraffin sections

We describe an in-situ RT-PCR method for the amplification of rhinovirus (RV) in fixed, paraffin-embedded HeLa cells employed as a model for human respiratory epithelium. HeLa cells were infected in-vitro with inocula of rhinovirus-16 ranging from 10(2) to 10(6) 50% tissue culture infective doses (TCID50), incubated for 18 h then fixed and processed into paraffin blocks. Sections of the cell preparation were subjected to standard RT-PCR, in-situ hybridisation (ISH) or in-situ RT-PCR using specific oligonucleotide primers or probes directed against the 5' non-coding region of RV RNA. RT-PCR was found to be capable of detecting RV16 RNA in one 8 microns-thick section of cells infected with the lowest virus titre. ISH using digoxigenin labelled oligonucleotide probes located RV16 signal in the majority of HeLa cells at the highest virus titre, but in few or no cells with the lowest virus titre. In contrast, in-situ RT-PCR detected RV16 in the majority of cells infected with this amount of RV16. There was a slight loss of morphology and fine localisation associated with the in-situ thermal cycling process. However, the sensitivity of in-situ RT-PCR is comparable to standard RT-PCR and greater than ISH for the detection of RV. In-situ RT-PCR has wide applications for sensitive localization of low copy viral and RNA sequences within cells to investigate the role of viruses in a variety of clinical conditions.

Demonstration of cytoplasmic tyrosinase mRNA in tissue-cultured cells by reverse transcription (RT) in situ polymerase chain reaction (PCR) and RT PCR in situ hybridization

To evaluate the specificity and applicability to the study of human tumor cells of the reverse transcription (RT) in situ PCR and RT polymerase chain reaction (PCR) in situ hybridization techniques, we examined five melanoma cell lines and five nonmelanoma lines for tyrosinase mRNA using primers specific for tyrosinase. Each procedural step was optimized and minutely controlled, and results from the in situ techniques and solution-phase RT-PCR were compared. All melanoma lines showed a specific pattern of perinuclear cytoplasmic reaction not seen in nonmelanoma lines. There was exact agreement between the results from the RT in situ PCR and RT-PCR in situ hybridization techniques and those from solution-phase RT-PCR. Ribonuclease digestion abolished cytoplasmic staining, as did omission of the reverse transcriptase step. Nuclear staining was seen in melanoma and nonmelanoma lines, apparently as a result of DNA synthesis from repair-replication and mispriming or nonspecific amplification. Neither high concentrations of deoxyribonuclease nor long incubation periods abolished this effect completely. Demonstration of cytoplasmic mRNA by RT in situ PCR and RT-PCR in situ hybridization specifically identifies cells of melanocytic lineage.

Processing of long-stored archival cervical smears for human papillomavirus detection by the polymerase chain reaction

The efficiency of a freeze-thaw method, a proteinase K/Tween 20 lysis method and a guanidinium isothiocyanate/silica beads method for DNA extraction from fixed and Papanicolaou-stained cells from the cervical cancer cell line Siha was measured by beta-globin polymerase chain reaction (PCR). The GTC/silica beads method, which appeared superior, revealed a human papillomavirus (HPV) general primer-mediated PCR sensitivity of 50-500 copies of HPV 16 per sample using dilutions of fixed and stained Siha cells. Application to archival cervical smears (n = 116) revealed that the yield and size of amplifiable DNA decreases with storage time. The longer the storage time, the more repetitions of the whole procedure, including the lysis step, were required to extract sufficient amplifiable DNA. In this way, an overall beta-globin PCR positivity for 98% of the smears was reached. Further analysis revealed that a maximum size of 200 bp could be amplified from smears stored for up to 9 years. The method was validated by demonstrating by PCR the same HPV types in archival smears and corresponding cervical biopsies of cervical cancer patients. In conclusion, the GTC/silica beads method appears suitable to process archival cervical smears for HPV detection by PCR. provided that stepwise adjustments are made until beta-globin PCR positivity is obtained and primers are chosen which amplify a maximum of about 200 bp.