Non-isotopic detection of HPV DNA in cervical smears using dot-blot hybridization

Detection of human papillomavirus by nonradioactive hybridization

The presence of the human papillomavirus (HPV) DNA sequence in cervical smears of women with cervical intraepithelial neoplasia (CIN) was investigated through dot blot using a nonradioactive method based on the principle of enhanced chemiluminiscence. From 154 samples examined, 59 (38.3%) had HPV-related sequences determined by dot-blot hybridization; among these, 18 samples (11.68%) reacted either to HPV 6/11 or to HPV 16/18 probes, 20 (12.98%) reacted to only HPV 16/18, and 21 (13.63%) reacted exclusively to HPV 6/11. The relative sensitivity of the method was controlled comparing the results of both tests with those obtained by Southern blot in 32 samples. The risk of HPV positivity was increased in women who first had intercourse at an early age and in patients with CIN II or III. Both associations were significant at the 95% confidence interval (CI). An increased risk of HPV positivity was also associated with patient's age at diagnosis, education levels, number of sexual partners, and use of oral contraceptives, but none of these factors were significant at 95% CI. Other risk factors for cervical cancer, such as the number of pregnancies or cigarette smoking, were not found to be associated with HPV infection and indicate that the association of these factors with cervical cancer probably is independent of HPV infection. Even if HPV is the major risk factor for CIN, this also supports a multifactorial model of cervical cancer etiology with an increased risk of HPV infection.

The human papillomavirus status of 114 endocervical adenocarcinoma cases by dot blot hybridization

The reported rate of human papillomavirus (HPV) positivity in cases of endocervical adenocarcinoma averages 38% (range, 0% to 100%) and, in contrast to cervical squamous cell carcinoma, HPV type 18 rather than type 16 is the predominant type. The HPV positivity rate and distribution of types (status) in 114 endocervical adenocarcinoma cases (37 in situ and 77 invasive) were determined by dot blot hybridization using biotinylated probes to HPV types 6, 11, 16, 18, 31, 33, and 35. Human papillomavirus DNA was present in 27% of in situ and in 44% of invasive adenocarcinomas, and in nearly all histologic subtypes of invasive adenocarcinoma. Human papillomavirus status was not predictive of tumor grade, volume, depth of invasion, lymph-vascular space involvement, age at presentation, or year of diagnosis. Type of HPV might influence the histologic subtype of invasive adenocarcinoma, as HPV type 16 predominated in the adenosquamous carcinomas while HPV type 18 was more frequently found in all other subtypes. Since only types 16, 18, and 33 were identified, an oncogenic role for HPV in endocervical carcinogenesis was supported.

Epstein-Barr virus-associated primary B-cell lymphoproliferative disorder of the cerebellum in an immune competent man

BACKGROUND

The role of the Epstein-Barr virus (EBV) in lymphoproliferative lesions has been widely accepted. Most of these lesions occur in patients who have deficiencies in their immune status. Lymphomatoid granulomatosis (LG) is a lymphoproliferative disorder originally characterized as an angiocentric, necrotizing, pleomorphic infiltrate of mononuclear cells. The etiology of LG is unknown. It was originally hypothesized that LG may represent an unusual lymphoid response to an infective organism, possibly EBV.

METHODS

Tissues from a previously healthy 60-year-old, healthy white man with primary cerebellar lymphomatoid granulomatosis were examined for the presence of EBV by nucleic acid hybridization.

RESULTS

The original LG lesion was a polyclonal B-cell proliferation that contained detectable amounts of EBV. Peripheral blood leukocytes were negative for EBV by the same assay. After an 18-month remission, a tumor reappeared near the site of the primary lesion, which had the histologic appearance of a lymphoma. The cells showed restricted clonality and contained a similar amount of EBV-related DNA as the original lesion. Peripheral blood leukocytes at the time of recurrence were negative for EBV. The patient died approximately 2 months after the recurrent tumor was detected.

CONCLUSIONS

This case demonstrated the development of a primary cerebellar B-cell lymphoproliferative disorder, histologically identical to lymphomatoid granulomatosis, that transformed into a lymphoma. The original tumor and the subsequent lymphoma contained, on average, several copies of EBV-related DNA per cell. Despite an extensive survey of the patient, no immune deficit was detected. Interpretation of the literature with the results of this case suggest that this instance of primary cerebellar LG arose as a consequence of an unusual EBV-associated B-cell lymphoproliferation. It is suggested that EBV may be a significant factor in the initiation of the abnormal proliferations of T-cells or B-cells reported in this disorder.

Dot blot hybridization in detection of human papillomavirus (HPV) infections in the oral cavity of women with genital HPV infections

The presence of human papillomavirus (HPV) types 2, 6, 7, 11, 13 and 16 DNA in cytologic scrapings of oral mucosa was studied in 309 women with genital HPV infections. The objective was to test the usefulness of oral mucosal scrapings (3 sequential swabs) in HPV DNA detection by dot blot hybridization. Based on hybridization with the 32P-labelled Alu-repeat probe, most samples contained more than 10(5) cells, which is an adequate number of cells for dot blot hybridization. Hybridization with 32P-labelled HPV DNA probes showed that 3.8% of the 309 women had an oral HPV infection. Of these, only 2 had clinical lesions indicative of HPV. All other oral HPV positive subjects had clinically healthy mucosa. HPV 6 was the most common (3.1%) type, followed by HPV 11 and 16 (1.1%). In 3 cases the genital mucosa harboured the same HPV type as found in the oral cavity. The results indicate that oral mucosal scraping results in adequate number of cells for dot blot hybridization with HPV DNA. Although the method is likely to result in an underestimation of latent and subclinical HPV infections, it is useful for studying the clinical HPV infections as well as other viral infections known to be present in exfoliated cells.

Europium(III) cryptate: a fluorescent label for the detection of DNA hybrids on solid support

We report here a new detection method for DNA hybrids on dot blots. The process utilizes DNA or oligonucleotide probes labeled with biotin, followed by recognition with a conjugate of streptavidin and europium cryptate, a time-resolved fluorescent label. Unlike the other lanthanide chelates, this label is an organic molecule embedding a europium ion into an intramolecular cavity. This structure has a better stability in diluted assay media, a good sensitivity even on solid support, and an elevated fluorescence lifetime which allows elimination of most of the background generated by other species present in the assay medium. This procedure is quantitative and detects down to 2 amol of a model DNA, which is similar to other nonisotopic (especially colorimetric) methods. The main advantages of this method are easy automation, quantitation, and rapidity of measurements.

Human papillomavirus type 16 associated with oral squamous carcinoma in a cardiac transplant recipient

Human papillomavirus type 16 (HPV 16) has been associated with a variety of squamous carcinomas, particularly those involving the anogenital tract. The authors report the development of an oropharyngeal carcinoma in a 43-year-old man approximately 20 months after cardiac transplantation while he was on a maintenance regimen of cyclosporine A and prednisone. The carcinoma was resistant to treatment, and he died of complications related to metastatic disease 3 years posttransplantation. Molecular biologic studies using nonisotopic-labeled viral DNA probes were done. In situ hybridization demonstrated the presence of HPV 16 DNA in the tumor cells. DNA dot blot analysis confirmed the presence of multiple copies of HPV 16 DNA within the tumor cells and their absence from adjacent normal-appearing tissue. Southern blot analysis suggested that the HPV 16 DNA was integrated into the tumor cell genome. With increasing recognition of the carcinogenicity of HPV type 16 infection, a role for this virus in the development of squamous cell malignancies in immunosuppressed organ transplant recipients is likely to be noted with increasing frequency.

A comparison of cervical scrapes for HPV typing by dot-blot hybridization obtained by wood and plastic spatulas

A cross-over study was designed to determine whether the type of spatula used to collect cervical cells influences the ability of dot-blot hybridization to detect HPV DNA. Fifty-nine patients had a cervical scrape with a wood spatula first and a plastic spatula second: 60 were scraped in the inverse order. The order of sampling did not affect the HPV DNA positivity rate, which was nearly similar for both wood and plastic spatulas (30 and 32%, respectively). Wood spatulas collected more cells and greater than 1 x 10(5) cells more often than plastic spatulas (P = 0.001 and 0.06, respectively). Non-purple (negative) dots were more frequent in samples obtained by wood than by plastic spatulas (P = 0.001). The study showed that cervical cell collection by wood spatulas is preferred as they harvest more cells, thus optimizing the sensitivity of the hybridization method, and the spatulas are also more economical. Although they yielded more non-purple dots, a reduction in these dots by using plastic spatulas did not result in a significantly increased HPV positivity rate.

Nonisotopic human papillomavirus DNA typing of cervical smears obtained at the initial colposcopic examination

To determine the prevalence of human papillomavirus (HPV) infection in 401 patients attending colposcopy for the first time, scraped cervical cells were investigated using dot blot hybridization and biotinylated DNA probes to HPV 6 and 11 (low-risk types) and 16, 18, and 33 (high-risk types). The HPV DNA was isolated from 52% of patients (low-risk types = 4%, high-risk types = 48%). Seventy-five percent had a cervical intraepithelial neoplasia (CIN)-condyloma. Low-risk types were infrequent (7%) and high-risk types (41%) predominant in condyloma/CIN I lesions when converse rates were expected. As CIN I lesions harboring high-risk types are at some risk of progressing to a higher grade dysplasia, colposcopic examination and treatment of this subgroup would seem justified. As expected, high-risk types were statistically associated with increasing grades of dysplasia. This hybridization method identified typeable HPV DNA in 60% of patients with a CIN-condyloma, and highlighted a unique HPV profile for this patient cohort.