Human papillomavirus (HPV) DNA sequences demonstrated by in situ DNA hybridization in serial paraffin-embedded cervical biopsies

Human papillomavirus infections in children: the potential role of maternal transmission

To date, more than 100 types of human papillomavirus (HPV) have been identified. In the past 20 years, there has been an increasing interest in HPVs because of their potential role in the pathogenesis of malignant tumors. HPV infections are known to affect predominantly adult, sexually active age groups, whereas skin warts, at various anatomic sites, are usually associated with younger individuals. The modes of viral transmission in children remain controversial, including perinatal transmission, auto- and hetero-inoculation, sexual abuse, and, possibly, indirect transmission via fomites. Recent studies on perinatal infection with HPV have been inconclusive. It is still unclear how frequently perinatal infection progresses to clinical lesions, whether genital, laryngeal, or oral. Conflicting reports have been published on the prevalence of HPV infections in children. The current consensus is, however, that newborn babies can be exposed to cervical HPV infection of the mother. The detection rate of HPV DNA in oral swabs of newborn babies varies from 4% to 87%. The concordance of HPV types detected in newborn babies and their mothers is in the range of 57% to 69%, indicating that the infants might acquire the HPV infection post-natally from a variety of sources. HPV antibodies have been detected in 10% to 57% of the children, and there is usually no correlation between seropositivity and the detection of HPV DNA in either the oral or the genital mucosa. There is also evidence that transmission in utero or post-natal acquisition is possible. The mode of in utero transmission remains unknown, but theoretically the virus could be acquired hematogenously, by semen at fertilization, or as an ascending infection in the mother. The understanding of viral transmission routes is important, particularly because several vaccination programs are being planned worldwide. The serologic response to HPV detected in different populations of young women or women at risk of cervical cancer might be due to genital infections, but the possibility that HPV infection has been acquired earlier in life through the oral mucosa or respiratory tract cannot be ruled out.

Detection of human papillomavirus in cervical intra-epithelial neoplasia, using in situ hybridization and various polymerase chain reaction techniques

One hundred and forty-eight randomly chosen neutral-buffered formaldehyde-fixed cervical biopsies in which cervical intra-epithelial neoplasia (CIN) I-III had been diagnosed were tested for HPV (human papilloma virus) DNA by in situ hybridization (ISH) and polymerase chain reaction (PCR). For ISH, we utilized a biotinylated panprobe and type-specific, genomic probe sets. For PCR, we used the general primers GP5/GP6 and their recently described, elongated version GP5+/GP6+, and included the modification of hot-start PCR. Amplified DNA was detected by gel electrophoresis and slot blot hybridization. The positivity rate of ISH was 59% for all biopsies and 69%, 62% and 46% for CIN I, II and III, respectively. The sensitivity of GP5/GP6 was 74% with cold-start PCR and 78% with hot-start PCR. When GP5+/GP6+ was used, the sensitivity increased to 89% with cold-start PCR and to 95% with hot-start PCR. Based on the most sensitive PCR technique, HPV detection was 93%, 95% and 96% in CIN I, II and III, respectively. The number of HPV types decreased with the severity of the lesion, and HPV 16 was the predominant type. Multiple HPVs were rare and almost all HPV-positive cases could be typed. ISH and slot blot hybridization correlated well regarding HPV typing specificity. Our results confirm that distinct HPV types are present in a high proportion of cases of CIN. The sensitivity of ISH is lower than that of PCR. Furthermore, the modified general primers GP5+/GP6+ give a higher yield than GP5/GP6, while hot-start PCR increases sensitivity even further.

Human papillomavirus (HPV) in vulvar dysplasia and carcinoma in situ

Surgical specimens from 62 patients with vulvar dysplasia and carcinoma in situ were morphologically investigated. Lesions were classified according to WHO (mild, moderate, severe dysplasia and carcinoma in situ) and according to Toki et al. (1991) (warty, basaloid, combined warty/basaloid or basaloid/warty types or mixed (warty, basaloid and simple) forms). Following the WHO classification, moderate dysplasia was shown in 4 cases, severe dysplasia in 47 and carcinoma in situ in 11 cases. Pure warty type was shown in 2 cases (both biopsy specimens). One case revealed pure simple dysplasia whereas no case of pure basaloid type was found. Various combinations of warty and basaloid types were shown in 52 cases and mixed forms in 7 cases. The results indicate that pure forms of warty and basaloid types probably do not exist. HPV DNA was detected by PCR in 51/58 cases (88%) (45 with HPV type 16 and 6 with HPV type 33) evenly distributed in all age groups and in all types of lesions (WHO and Toki et al. 1991). By ISH HPV was detected in 24/62 cases (39%) (21 with HPV type 16/18 and 3 with HPV type 31/33), nearly always in warty areas. All these cases were positive for the same virus type by PCR. No case revealed more than one type of HPV. HPV type 6, 11, 18, and 31 were not detected by PCR. The results indicate a correlation between HPV type 16 and 33 and dysplasia/carcinoma in situ in the vulva.

Detection of human papillomavirus infection by non-isotopic in situ hybridisation in condylomatous and CIN lesions

AIMS

To study the value of non-isotopic in situ hybridisation (NISH) in detecting human papillomavirus (HPV) infection in female genital lesions positive for the virus by conventional histology but negative by filter DNA hybridisation.

METHODS

Forty three cases, which showed the histological hallmarks of the HPV infection but produced negative results in filter dot blot hybridisation tests (Vira Pap and Vira Type kits), were identified in the course of an investigation of 304 vaginal, vulvar, and cervical samples from 267 patients. These cases were studied by NISH for the presence of HPV infection.

RESULTS

In 28 (65%) of the cases NISH gave a positive hybridisation signal. In 26 cases (96%) the signal was diffuse, and in two (4%) punctate or diffuse, representing episomal and episomal or integrated HPV DNA, respectively. In most cases only a few HPV positive cells were discernible.

CONCLUSION

NISH is a more sensitive technique than dot blot hybridisation, detecting HPV infection in most cases which show histological HPV atypia but which remain negative in filter DNA hybridisation. Thus NISH is useful as an additional technique to verify the presence of HPV in lesions which remain negative in filter hybridisation tests.

Human papillomaviruses associated with cervical intraepithelial neoplasia. Great diversity and distinct distribution in low- and high-grade lesions

All together, 30 genital human papillomavirus (HPV) types have been characterized so far. To evaluate the importance of HPV diversity in associated cervical diseases, we analyzed 188 biopsy specimens obtained from patients with a recent diagnosis of cervical HPV infection or intraepithelial neoplasia (CIN). Of these 188 specimens, 116 were classified as low-grade CIN (48 cases), high-grade CIN (53 cases), condylomata acuminata (10 cases), flat condylomas (five cases). Seventy-two specimens were considered nondiagnostic. Using probes specific for 18 genital HPV types, HPV DNA sequences were detected by Southern blot hybridization in 100 lesions and 21 nondiagnostic specimens. When further analyzed by the polymerase chain reaction, eight HPV-negative biopsy specimens, four CIN, and four nondiagnostic specimens were positive. Of the 129 positive biopsy specimens, 92 contained at least one of 18 known HPV types and 37 HPV that have not yet been identified. Nine specimens had more than one type. Thirteen HPV types were identified in CIN. The detection rate of HPV 16 increased from 21% in low-grade CIN to 57% in high-grade CIN. HPV 18 was detected in only 3% of CIN; HPV 31, 33, and 35 were found in 8%. HPV 30, 39, 45, 51, 52, 56, 58, and 61 were detected in 44% of low-grade CIN but in only 8% of high-grade CIN. Unidentified HPV were detected in about 25% of low-grade and high-grade CIN. Fifty-seven CIN positive for at least one HPV type were further analyzed by in situ hybridization. Thirty-five (65%) biopsy specimens were positive, including 21 of 24 low-grade CIN and 14 of 33 high-grade CIN. Ten of the 13 previously identified HPV types were detected. Thus, CIN represents an heterogeneous disease from a virologic viewpoint. This fact could explain their variable clinical evolution.

Ten year follow-up study of women presenting to a genitourinary medicine clinic with anogenital warts

One hundred heterosexual women presenting at our clinic in 1979 with anogenital warts, were reviewed 10 years later. Median duration of warts following initial clinic attendance was 2 months (range 0-120 months). In 1979 cervical PAP smear results were available for 76 patients; cervical intraepithelial neoplasia (CIN) was seen in 15/76 (19.7%) women; 3 (4%) women had low grade CIN, 12 (15.7%) women had high grade CIN. Nineteen women had had treatment for CIN between 1979 and 1989, 7 laser ablation, 9 cone biopsy, 2 laser ablation and cone biopsy, and one woman laser ablation, cauterization and cone biopsy. At 10-year follow-up in 1989 4/100 women had anogenital warts, 12/100 women had cytological evidence of CIN (7 low grade, 5 high grade), and 37/100 women had CIN detected on colposcopic biopsy (31 low grade, 6 high grade). No women developed invasive cervical carcinoma during the study period. CIN lesions, detected in 1979, regressed without any treatment in 2 women. Colposcopic biopsy was 3.1 times more sensitive than single cervical PAP smear at detecting CIN (4.4 times as sensitive in detecting low grade CIN; 1.2 times as sensitive in detecting high grade CIN). In 1989 CIN was detected in 7/19 (36.8%) of women who had undergone cervical treatment between 1979 and 1989, and in 35/81 (43.2%) of women having no cervical treatment within this period (chi squared P greater than 0.5). These findings suggest that cervical laser ablative therapy and cone biopsy do not in the long term influence the natural history of cervical human papilloma virus-associated disease (CIN) in women with anogenital warts.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of four non-radioactive and 35S-based methods for the detection of human papillomavirus DNA by in situ hybridization

Human papillomavirus DNA was detected in 40 condylomatous lesions of various sites (vulva, cervix, larynx, penis and anus) by in situ hybridization using 35S-labelled probes and four non-radioactive probes to compare the various sensitivities of these techniques on the same material (formalin-fixed and paraffin-embedded sections). Radioactive probes yielded 28 positive results out of 40 (70%). Sulphonated probes (HybriCyte kit) also gave 28 positive results with a fine pattern of hybridization grains and equal sensitivity to 35S-labelled probes. Biotinylated and digoxigenin-labelled probes gave analogous results (25 positive reactions with the PathoGene kit, 26 with the Viratype kit, and 25 with digoxigenin-labelled probes) but are slightly less sensitive than radiolabelled and sulphonated probes especially when the signal is weak.

Cytohistology, colposcopy and in situ hybridization in cervical preneoplastic lesions: a correlative study

Formalin-fixed, paraffin-embedded cervical tissues from 106 patients which exhibited a colposcopically atypical transformation zone, were examined for the presence of HPV DNA by in situ hybridization using biotin-labeled HPV 6/11 and 16/18 DNA probes. From the comparative study between histologic, cytologic, colposcopic findings and virologic results it is confirmed that HPV 6/11 DNA is detected more frequently in the less severe lesions, whereas HPV 16/18 DNA is predominantly found in the most severe dysplastic lesions.

Detection of human papillomavirus DNA in genital lesions by using a modified commercially available in situ hybridization assay

A modified, commercially available DNA-DNA in situ hybridization test that uses biotinylated probes for the identification of human papillomavirus (HPV) DNA types 6/11, 16/18, and 31/33/35 was evaluated. HPV DNA was detected in 314 of 787 (40%) histologically abnormal genital biopsy specimens by using the ViraType in situ assay (Life Technologies, Gaithersburg, Md.), in which the hybridization time was increased from 2 to 16 h. Ninety percent of positive condyloma acuminata specimens contained HPV type 6/11 DNA. The prevalences of HPV DNA for cervical intraepithelial neoplasia I, II, and III lesions by this in situ hybridization test were 42, 54, and 55%, respectively. The combined prevalence of HPV type 16/18 and 31/33/35 DNAs increased with the severity of the lesion, while the prevalence of type 6/11 DNA decreased. HPV type 6/11 DNA was found only in 1 of 16 (6%) positive cervical intraepithelial neoplasia III specimens. HPV type 16/18 and 31/33/35 DNA was detected in 11 of 16 (69%) and 4 of 16 (25%) in situ hybridization-positive cervical intraepithelial neoplasia III specimens, respectively. Thus, the observation that certain "higher-risk" HPV genotypes are associated with upper-grade cervical precancer lesions was confirmed by this commercial hybridization system. In general, the assay was found to be well suited for use in the clinical laboratory. The ViraType in situ procedure modified for a longer hybridization time may be helpful in identifying lesions containing higher-risk HPV strains.

Demonstration of human papillomavirus DNA by nucleic acid in situ hybridization in paired histologically abnormal cervical biopsies obtained at the same patient visit

Fifty-four pairs of cervical biopsies ranging from minimal dysplasia to severe dysplasia were studied for the presence of human papillomavirus DNA by in situ hybridization. Two assays were performed on each biopsy. A 16 hour hybridization was used in one assay, while a 40 hour hybridization was utilized in the second assay. Increasing the hybridization time to 40 hours did not significantly increase the detection rate of HPV compared to the rate found using the 16 hour hybridization. Also, no difference in the detection rate of HPV was found by using one biopsy of the pair over the other biopsy of the pair. However, the performance of a single in situ assay on only one biopsy from each patient significantly underestimated the true prevalence of HPV. A single assay only detected 21/33 (64%) patients with HPV. Implications of multiple testing of all histologically abnormal biopsies is discussed in relation to prospective follow-up studies determining the usefulness of HPV typing in patient management.

Detection of five different human papillomavirus types in cervical lesions by in situ hybridization. A study of 110 cases using sulfonated probes

Several findings suggest an etiologic relationship between genital tract squamous cell carcinoma and certain types of human papillomavirus (HPV). Detection of these HPV types in cervical lesions considered as preneoplastic states (ie, cervical intraepithelial neoplasia or CIN) is extremely important but difficult because the morphology of these states is highly heterogeneous and clinical course is rarely predictable. In situ hybridization (ISH) is the only technique allowing correlation between HPV type and tissue or cell morphology. In this report, 110 biopsy specimens from uterine cervix lesions were studied: 66 CIN, 10 invasive carcinoma, 28 metaplasia, and six condyloma acuminata. A new ISH technique based on direct modification of DNA probes by sulfonation was used. The hybridized DNA was revealed first by a specific monoclonal antibody against sulfonated DNA, and then by an alkaline phosphatase system. In order to determine the sensitivity level of this method, 14 biopsy specimens were also submitted to Southern blot hybridization. Five probes were used separately (HPV 6, 11, 16, 18, and 33) for each biopsy specimen. Results of ISH were correlated with morphologic criteria such as number of koilocytes and mitoses. Oncogenic HPV was found exclusively in CIN. The number of labeled cells varied with CIN grade. These data suggest that, whatever the grade, CIN represents a unique preneoplastic process, and that HPV replication depends on the squamous maturation of the pathologic epithelium.

In situ hybridization analysis of human papillomavirus DNA segregation patterns in lesions of the female genital tract

Various histologic features may be used to divide human papillomavirus (HPV)-related lesions of the genital tract into two groups: condylomata and "low-grade" or grade 1 cervical intraepithelial neoplasias (CIN 1) versus "high-grade" or grade 2 and 3 intraepithelial neoplasias. Using in situ hybridization analysis we correlated HPV DNA type with histologic features in 350 biopsies of lesions from the cervix, vulva, and perianal region. HPV DNA was most commonly found in vulvar and perianal condylomata (39/46, 85%), whereas the rate in CIN 1 lesions was 72% (86/120). The rates were 53% (40/76) and 57% (12/21) in CIN 2/3 and vulvar intraepithelial neoplasm (VIN) grades 2 and 3, respectively. The HPV type in all but 2 of the 39 perianal and vulvar condylomata which contained HPV was 6/11. Despite their similar histologic features, the HPV type in only 23 of 86 (27%) CIN 1 cases with detectable HPV was 6/11 compared to 31 of 86 (36%) which contained HPV 16-related DNA and 32 of 86 (37%) which contained HPV 31,-33, or -35-related DNA. The viral DNA in the majority of CIN 2/3 lesions and all of the VIN 2/3 lesions was HPV-16 related; no CIN 2/3 or VIN 2/3 lesion had HPV 6/11-related DNA. It is concluded that although cutaneous genital tract condylomata are highly associated with HPVs of low oncogenic potential (types 6 and 11), these HPV types are not as frequent as the oncogenic HPVs (16, 31, 33, and 35) in CIN 1 lesions. Further, HPV 6/11 appears to be very rarely associated with CIN 2/3 or VIN 2/3 lesions.

Basic concepts and practical applications of recombinant DNA techniques in detection of human papillomavirus (HPV) infection. Review article

Recent studies on the role of infectious agents in the pathogenesis of malignancy have demonstrated a strong association between HPV and several human benign and malignant epithelial neoplasms. There are 60 distinct types of HPV, of which HPV 16, 18, 31, 33, 35 and 39 have been associated with squamous cell neoplasia of the genital tract. Rapid progress in the field of recombinant DNA technology with the availability of specific probes has enabled the detection of HPV genomic sequences in characteristic HPV lesions. In addition, HPV sequences have been found in malignant squamous cell lesions, and even in normal tissues lacking the morphologic signs of HPV infection. Currently, hybridization analysis of the nucleic acid is the most reliable method for diagnosis of HPV infections, also permitting the genotyping of these viruses. A variety of hybridization procedures have been developed with different sensitivities and specificities. Despite the divergent technical modifications, however, all hybridization tests working according to the same basic principles. The double helix of DNA composed of two complementary polynucleotide chains can be opened by heating or by increasing pH. Cooling of the two strands allows reassociation. Labeled HPV DNA or RNA probe hybridizes with the complementary sequences allowing the detection of HPV sequences in the samples. Hybridization assays can be conducted under conditions in which virtually all HPVs will be detected, but not specifically typed (low stringency) or under conditions in which the type can be identified (high stringency). Widely divergent results have been reported both in prevalence of HPV infection and distribution of different HPV types in the genital tract. These discordant results have been explained on the basis of sampling effects, differences in histopathological diagnosis, geographical variations in HPV types and interlaboratory variation in HPV detection and typing techniques. In this review the various procedures for detecting HPV sequences by hybridization and related techniques are shortly described.

In situ hybridization analysis of HPV DNA in cervical precancer and cervical cancers from China

A series of 103 cervical biopsies derived from 103 women during July 1958 to September 1963 from Beijing, China were investigated with in situ hybridization for the presence of HPV6, 11, 16, 18, 31 and 33 DNA. The mean age of the patients was 46.1 + 10.6 years with a range of 24-74 years. Morphological features of HPV infection were found in 80 (77.7%) biopsies. Invasive cervical cancer was diagnosed in 43 biopsies and cervical intraepithelial neoplasia CIN I, CIN II and CIN III in 9, 9, and 27 cases, respectively. A total of 63.1% (65/103) of the lesions had morphological features of HPV infections associated with CIN or invasive carcinomas. Altogether, 31.1% (32/103) of the biopsies were shown to contain HPV DNA. Of the cases showing HPV morphology, 43.1% were HPV DNA positive. HPV16 (30/32) was the most frequent type, followed by HPV11 and 18, whereas no lesions with HPV6, 31 or 33 were found. A total of 19/43 (44.2%) of the invasive carcinomas contained HPV DNA. HPV DNA positivity and the grade of CIN showed a statistically significant correlation (P = 0.0011). Our study demonstrated the presence of HPV in cervical lesions among Chinese women in the late 1950's and early 1960's when a single sexual partner was the rule and also supports the concept that HPV has as an important etiological role in cervical cancer, the highest risk being associated with HPV type 16. The applicability of in situ hybridization in retrospective assessment is emphasized.

Detection of human papilloma virus in women referred for colposcopy. A comparison between different diagnostic methods

Various methods presently available for the diagnosis of genital Human Papilloma Virus (HPV) were compared regarding their sensitivity in women referred for specific diagnosis and treatment because of atypical Pap smears or clinically suspected neoplasia. Colposcopic examination was performed in all cases. In addition to taking a second Pap smear, cell suspensions were made from 105 women and analysed by the Filter In Situ Hybridization (FISH) technique and tested for HPV 6 + 11 and HPV 16 + 18 + 31. The FISH technique was also used for the possible detection of HPV-DNA in a reference material comprising 119 apparently healthy women with normal Pap smears. Colposcopically directed cervical biopsies in altogether 196 specimens were obtained from 155 women for histopathological examination and also for the detection of HPV-DNA by the Southern blot hybridization technique. These specimens were tested for the presence of HPV 6, 11, 16, 18, 31 and 33. Three per cent of the women with and 34% without cytological signs of HPV in Pap smears had cervical intraepithelial neoplasia (CIN) III according to histopatology. CIN III was present in 35% of biopsies with and 59% of biopsies without histological signs of HPV in the biopsies. Altogether 46% of the women were HPV-DNA positive. Of the women analysed by Southern blot, 39% were HPV-DNA positive. Of the samples analysed by FISH, 27% with atypical cells were HPV-DNA positive, compared with 11% of the samples from reference women with normal cytology.(ABSTRACT TRUNCATED AT 250 WORDS)

Anal condylomas in men. 1. Histopathological and virological assessment

A series of 128 biopsy specimens from anal condylomas in 73 homosexual or bisexual and 38 heterosexual men (mean (SD) age 31.8 (9.6) years) were subjected to histological assessment and human papillomavirus (HPV) typing by in situ DNA hybridisation with 35S-labelled HPV 6, 11, 16, 18, 31, and 33 probes. Most patients were also tested serologically for antibodies to human immunodeficiency virus (HIV). As evaluated on light microscopy, most (74%, 95/128) of the lesions were exophytic (papillary) acuminate warts, 15% (19) were flat, and 11% (14) were pigmented papulous lesions. No signs of anal intraepithelial neoplasia (AIN) were seen in 70% (90) of the 128 biopsy specimens (NAIN), 27% (35) were classified as showing AIN I, and another 2% (three) as AIN II. AIN was significantly (p less than 0.05) more often associated with papulous lesions, only 43% (6/14) of which showed NAIN compared with 72% (68/98) of acuminate condylomas. The duration of disease was directly related to the presence and severity of AIN in the lesions; thus in 47 lesions that had been present for more than 12 months, NAIN was found in 31 (66%), AIN I in 14 (30%), and AIN II in two (4%). HPV DNA of at least one of the six types tested for was detected in 109/125 (87%) lesions. HPV 6 and HPV 11 were the two most common types, comprising 57% (62) and 37% (40), respectively, of the 109 HPV DNA positive cases. Only seven (6%) biopsy specimens were associated with any of HPV types 16, 18, 31, or 33, which carry a high risk of potential malignant transformation. No association was found between sexual preferences of patients and the incidence of any of the various HPV types. Neither did the distribution of the various HPV types differ between men with antibody to HIV and those without antibody. All the men with antibody to HIV were homosexual or bisexual. On microscopy, 93% (38) of 41 lesions containing HPV 11 and 75% (48/64) of HPV 6 lesions were of the acuminate wart type; in comparison, the remaining 16 HPV 6 lesions were equally either flat or papulous (eight, 13% each). Of the 64 HPV 6 and 41 HPV 11 associated lesions, 73% (47) and 63% (26), respectively, were classified as NAIN. Only two lesions were associated with HPV 16, and both showed mild dysplasia. On the other hand, two HPV 6 induced lesions were associated with AIN II. No differences were found between HPV 6 and HPV 11 in duration of disease; (39%, and 27% respectively, had been present for more than 12 months). The results showed that overt anal wart disease was associated with HPV types 6 and 11 in most cases. Although HPV types considered as being of higher oncogenic potential were detected relatively rarely, the associated AIN in a relatively high proportion (31% 32/105) of HPV 6 or 11 induced lesions indicated that a malignant potential, even for HPV 11 associated anal warts, cannot be excluded.

Human papillomaviruses: are we ready to type?

The issue of determining which human papillomavirus (HPV) is present in a clinical specimen (typing specimens for HPVs) is receiving attention because HPVs cause condyloma acuminata and are associated with the continuum of disease which ranges from dysplasia to invasive genital cancer. Morphological inspection of precancerous lesions is not sufficient to determine which lesions will progress and which will not. A number of research tools based primarily on deoxyribonucleic acid hybridization have been developed. These permit identification and typing of HPV in genital tract scrapings or biopsies. Some HPV types (e.g., HPV-16 and HPV-18) have been identified in high-grade dysplasias and carcinomas more commonly than other types (e.g., HPV-6) and have been designated "high risk" types for cervical cancer. Thus, the question arises whether HPV typing would improve patient management by providing increased sensitivity for detection of patients at risk or by providing a prognostic indicator. In this review, the available typing methods are reviewed from the standpoint of their sensitivity, specificity, and ease of application to large-scale screening programs. Data implicating HPVs in the genesis of genital tract cancers are reviewed, as is the association of specific HPV types with specific outcomes. We conclude that there is currently no simple, inexpensive assay for HPV types, although such assays may be developed in the future. Analysis of the typing data indicates that, while HPV types can be designated high risk and low risk, these designations are not absolute and thus the low-risk group should not be ignored. In addition, interpretation of the data is complicated by finding high-risk types in individuals with no indication of disease. Insufficient data exist to indicate whether knowledge of the presence of a given HPV type is a better prognostic indicator than cytological or histological results. Thus, more research is needed before it can be determined whether typing information will augment the method currently in use for deciding treatment regimen and whether it warrants widespread use.

Papillomavirus. Effects upon mother and child

Papillomaviruses are widespread, sexually transmitted agents with an increasing prevalence. They are associated with a significant risk of genital carcinoma in infected women. Because they can be transmitted to the fetus before or during birth, they are also a risk to the infant born to an infected woman. Laryngeal HPV infections, while presumably much less prevalent than genital tract infections, are associated with a high degree of morbidity and a significant degree of mortality when they cause laryngeal papillomas. Therefore, transmission of these viruses to the fetus is a major problem. Much more information regarding mode of transmission and possible cure for this infection is needed in order to reduce the risk of laryngeal papillomatosis in infants in the future.

Morphologic and immunohistochemical evidence of human papillomavirus capsid antigen in smokeless tobacco keratoses from juveniles and adults

Seventy-seven tissue samples from patients with either degree I, II, or III smokeless tobacco keratoses were examined. The tissues were evaluated for the presence of human papillomavirus (HPV) antigen by immunocytochemical staining. Capsid antigen could be identified in sixteen cases (20.78%). This investigation further supports the concept that smokeless tobacco-associated leukoplakias can be correlated with HPV infection.

Factors associated with progression of cervical human papillomavirus (HPV) infections into carcinoma in situ during a long-term prospective follow-up

In the course of a prospective study of 508 women with papillomavirus (HPV) lesions of the uterine cervix, 66 lesions that progressed into carcinoma in situ (CIS) were identified and treated by conization during a mean follow-up period of 35 months. The lesions were investigated with light microscopy and with in-situ DNA hybridization using 35S-labelled probes for HPV 6, 11, 16, 18, 31 and 33. After radical cone treatment, 11 of the 66 women (16.7%) have presented with a recurrent HPV infection. The recurrence rate increased with the duration of the follow-up period from less than 10% at the mean follow-up of 25 months to 16.7% at the most recent follow-up at 35 months. Most of these 66 HPV lesions (89%) presented with concomitant CIN in the first punch biopsy, but it is noteworthy that the other 11% presented without concomitant CIN. HPV DNA of at least one of the six types examined was found in 73% of the first biopsies and it is noteworthy that the so-called 'low-risk' types, HPV 6 and 11, were found as frequently as the 'high-risk' types, HPV 16 and 18 (18% and 17%, respectively). This would suggest a similarity in the biological behaviour of these two HPV groups. Although the concept of the 'high-risk' and 'low-risk' HPV types may remain at least partially valid, it is imperative to realize that infection by HPV 6 and 11 by no means excludes the possibility for clinical progression into CIS and eventually to an invasive carcinoma.

Expression of a testis-specific hsp70 gene-related RNA in defined stages of rat seminiferous epithelium

Changes in the level of a testis-specific hsp70 gene-related transcript (hst70 RNA) and its cellular localization during the cycle of rat seminiferous epithelium have been investigated. Segments of seminiferous tubules at defined stages of the cycle were isolated in living condition by transillumination-assisted microdissection and the exact stages identified by phase-contrast microscopy of live cell squashes. The levels of the hst70 RNA were determined by Northern and slot blotting of whole cell lysates. High levels were found in stages XII-XIV and I to early VII of the cycle, and low levels were found in other stages, i.e., late VII (VIId) through VIII-XI of the cycle. The in situ hybridization revealed that the hst70 gene was activated in late pachytene primary spermatocytes during stage XII of the cycle, and that mRNA was then present in cells during differentiation through diakinesis, meiotic divisions, and early spermiogenesis (steps 1 through early 7). The activation of the gene coding for hst70 RNA shortly before meiotic divisions may indicate that the gene product is needed either during differentiation of late spermatocytes into spermatids or later during spermiogenesis, and that the mRNA may be stored in early spermatids.

Localization of protamine 1 mRNA in different stages of the cycle of the rat seminiferous epithelium

A mouse protamine 1 cDNA probe was used to study P1 protamine gene expression during the cycle of the seminiferous epithelium in the rat. In situ hybridization experiments showed that transcription of the P1 protamine mRNA starts in the middle of step 7 of spermiogenesis during substage VIIc. The mRNA levels stay high in steps 7-14 spermatids but decrease during steps 15-16 and are virtually undetectable in steps 17-19 spermatids. Northern blot analyses of RNAs isolated from microdissected pools of seminiferous tubules show high P1 protamine mRNA concentrations during stages VIIc-XIV-III of the cycle and lower levels during stages IV-VIIb. Owing to a post-transcriptional shortening of the poly(A) tail by 130 bases, a decrease in the size of protamine 1 mRNA from approximately 580 to 450 nucleotides was observed in stages XIII-XIV suggesting an initiation of protamine 1 synthesis in step 13-14 spermatids. In stages II-VI (steps 16-18 spermatids), only the smaller size protamine 1 mRNA was detectable. The expression of protamine 1 mRNAs has been localized in the very last phase of the haploid gene activity. Although the in situ hybridization suggests a disappearance of protamine 1 mRNA after step 16 of spermiogenesis, Northern blot analysis shows that low levels of mRNA are present during the period of final condensation of the chromatin, reflecting the association of protamine with DNA.

Synthetic oligonucleotide probes for the detection of human papilloma viruses by in situ hybridisation

Using the published nucleotide sequence data for human papilloma virus (HPV) types 1, 6 and 16, sequences of 30 bases in length from the beginning of the E6 open reading frame (ORF) were selected. Oligonucleotides were synthesised on an Oswel Gene Synthesizer and labelled at the 3' end with biotin using the enzyme terminal transferase. In situ hybridisation was carried out on paraffin sections of wart and cervical tissues mounted on silanated slides. A 2 h hybridisation step allowed the whole process to be completed within one working day. The technique successfully demonstrated the presence of HPV-1 in skin warts, and of HPV-6 and HPV-16 in genital warts and cervical lesions. This simple approach has diagnostic potential for the detection and typing of papilloma viruses in biopsy material.

Screening of premalignant cervical lesions for HPV 16 DNA by sandwich and in situ hybridization techniques

A series of 97 cervical smears and 69 directed punch biopsies derived from 84 consecutive women prospectively followed-up for cervical HPV (human papillomavirus) infections were studied using the sandwich hybridization and in situ hybridization techniques with HPV 16 DNA probes. The aim was to test the sensitivity and applicability of these two techniques in routine diagnosis of cervical HPV infections from smears. As a measure of specimen adequacy, the number of cells recovered in the cervical scrape was determined along with HPV 16 DNA in the sandwich hybridization test using human pro-alpha 2(I)-collagen gene probe. CIN (cervical intraepithelial neoplasia) was suggested in 56% of the patients by the Pap smear, and disclosed in 65% of the biopsies. HPV 16 DNA was present in 57% of cervical scrapes consistent with CIN, i.e., were of Pap smear classes III or IV. Forty percent of the scrapes not suggestive of CIN, i.e., Pap smear classes I or II, also contained HPV 16 DNA. The detection rate for HPV 16 DNA of the sandwich hybridization method was 89% of that of the in situ method in adequate scrapes, but only 43% in cell-poor specimens. The number of HPV 16 DNA-positive scrapes as compared with the total number of diagnoses obtained by studying also the biopsies was 31/36 (69 patients). The results indicate that the cervical scrape as a noninvasive specimen is applicable for screening of cervical HPV infections, and it can be studied with acceptable sensitivity by the rapid sandwich hybridization technique. However, if a punch biopsy is indicated it should be studied using the in situ hybridization technique that allows more sensitive detection of HPV DNA than any other hybridization method and enables the analysis of several HPV types in the same sample instead of only one HPV type in the scrapes.

Sensitivity of in situ hybridization techniques using biotin- and 35S-labeled human papillomavirus (HPV) DNA probes

In order to evaluate the sensitivity of our modified in situ DNA hybridization technique using biotinylated probes, formalin fixed, paraffin embedded biopsies from 20 cervical lesions known to contain human papillomavirus (HPV) DNA were re-examined by the technique using both 35S-labeled- and biotinylated HPV DNA probes. The probe concentrations as well as the detection limits of biotin probing were screened by spotting known amounts of HPV 16 DNA on nylon filter, and allowed to hybridize with biotinylated HPV 16 DNA probe. By this method, 4 pg of HPV 16 DNA could be detected using a probe concentration of 0.2 micrograms/ml. HPV DNA could be demonstrated in all 20 biopsies with both hybridization techniques. However, signals in subrabasal cells were detected more frequently with biotin- than with 35S-labeled probes. Additional experiments were performed using three cervical cancer cell lines (with known copy numbers of HPV DNA), to assess the detection limits of HPV infections by the in situ hybridization techniques. The CaSki cells (500-600 HPV 16 copies/cell) were unequivocally positive with both labelling systems. HeLa cells (10-50 HPV 18 copies/cell) were positive with the biotin probing in 10/10 smears, as compared to 7/10 smears when 35S-labeled probes were used. Radioactive probing was inferior to biotinylated probing in detecting the signals in SiHa cells (1-2 HPV 16 copies/cell). This is because even weak background signals could mask true positive signals when 35S-labeled probes are used. In contrast, no background is generated with the biotinylated probes, detected with streptavidin-biotinylated alkaline phosphatase complex. In situ hybridization with biotinylated DNA probes is as sensitive as techniques using 35S-labeled probes for detecting HPV infections in routine cervical biopsies or smears.

Presence of human papilloma virus types 16 and 18 in genital warts and cervical neoplasias

Certain types of human papilloma viruses (HPV) are associated with human genital proliferative diseases, and among them HPV16 and HPV18 seem to play an important role in the occurrence of cervical cancer. We used restriction enzyme analysis and molecular hybridization, in order to investigate the type of viral infection and the physical state of viral DNA in gynecological benign, pre-malignant and malignant lesions. HPV6/11 specific sequences could only be detected as episomes and this in benign lesions classified as condylomata acuminata. On the other hand, HPV16 and HPV18 sequences were detected in non-malignant lesions such as flat condylomata (7 out of 14 cases), pre-malignant lesions including cervical intra-epithelial neoplasias (10 out of 20 cases), and most frequently in cervical invasive cancers (21 out of 27 cases). In a large number of virus-positive cases, HPV16 and HPV18 could only be discerned in forms consistent with the existence of episomes and/or randomly integrated head-to-tail oligomers. However, some invasive carcinomas and cervical intra-epithelial neoplasias contained, in addition, clonal outgrowths with detectable virus-cellular junction fragments of the integrated viral genomes. In the light of these data, monitoring the type of viral infection proves to be an important adjunct to histological analysis when assessing those patients affected by condyloma or cervical intra-epithelial neoplasia who are at risk for developing invasive carcinoma.

Human papillomavirus DNA in normal, metaplastic, preneoplastic and neoplastic epithelia of the cervix uteri

Colposcopically directed cervical punch biopsies from 362 patients were screened by Southern blot hybridization for the presence of DNA of human papillomavirus (HPV) 6, 10, 11, 16, 18, 31 and 33. The biopsies represented original squamous epithelium, epithelium of metaplastic origin, different stages of cervical intraepithelial neoplasia (CIN) and invasive carcinomas. HPV6/11, 16, 18 and 31 were detected in 2.9% to 13.7% of histologically normal epithelia. HPV6/11 prevailed in CIN I. HPV16 was clearly more abundant than other HPV types in high-grade CIN and invasive cancers (50%-60%), compared with healthy epithelium. Restriction enzyme cleavage analysis of DNA from primary cancers and corresponding metastases proved the stable association of HPV16 DNA with invasive tumor cells. Preliminary follow-up studies of CIN II patients suggested that HPV16-associated lesions are relatively more likely to persist or to progress. Taken together, the data support the notion of a higher oncogenic potential of HPV16.

Altered expression of filaggrin in human papillomavirus (HPV) lesions of the uterine cervix

A series of 64 punch biopsies collected from women prospectively followed-up for cervical Human papillomavirus (HPV) infections (with and without CIN), and 38 control biopsies (normal epithelia, and classical CIN) were analysed for expression of filaggrin (a histidine-rich protein constituent of keratohyalin granules) using the ABC technique and polyclonal antibody. HPV typing was completed using the in situ hybridization technique with DNA probes for HPV 6, 11, 16, 18 and 31. Three patterns of filaggrin distribution were differentiated: pattern I, all layers above the basal cells stained positive regularly; pattern II, all layers above the basal cells stained irregularly, and pattern III, scattered superficial cells stained positive. There was a significant difference between HPV-noCIN and HPV-CIN lesions in their filaggrin patterns, pattern I being present in the majority (77.7%) of HPV-noCIN lesions, as contrasted to HPV-CIN lesions, where pattern III was the predominant one (43.5%), followed by pattern II (32.6%). In HPV-CIN as well as in CIN lesions, pattern I was inversely related to the grade of CIN, being entirely absent in HPV-CIN III and CIN III. A significant difference exists between CIN and HPV-CIN lesions, concerning the presence of pattern III (4.3% and 43.5%, respectively, P less than 0.001). The difference was less dramatic with regard to pattern I (30.4% and 21.7%, respectively, P less than 0.05). In the lesions containing HPV 6, 11 or 31 DNA, filaggrin distribution was shown to be more close to that of the normal epithelium (I 36.7%, and II 34.7%), while in the HPV 16 and 18-infected cases, pattern III was the predominant one (46.7%). The assessment of filaggrin pattern in HPV lesions might be of help in evaluating the severity of the disturbance of keratinocyte differentiation induced by the progression of HPV infections.

Nucleic acid sandwich hybridization in detection of HPV 16 DNA: technique and its clinical application

Nucleic acid sandwich hybridization technique was used for detection of HPV 16 specific DNA in cervical scrapes. Alternating HPV 16-PstI fragments were cloned into plasmid pBR322 and phage M13mp10. pBR322-clones were used as 32P-labelled probe reagents and the M13mp10 clones as catching reagents in the assay. The detection limit of the test proved to be 1-5 X 10(5) HPV 16 molecules per test. A weak cross reaction was seen with HPV 31 DNA but not with the other types tested, e.g. HPV 6, 11, 18 and 33. Cervical scrapings obtained from 163 consecutive patients included in a prospective follow up study were analyzed for HPV 16 DNA with the sandwich hybridization method, dot-blot hybridization being used as a reference method. Sandwich hybridization assay detected 25 positive cases out of 163 specimens (15.3%). Of these 6 and 3 additional specimens were positive in dot-blot hybridization assay. HPV 16 DNA was related to higher PAP grades, and HPV 16 appeared more frequently in HPV CIN than HPV NCIN lesions. None of the infections caused by HPV 16 regressed, and 24% progressed during the follow up.

Detection of human papillomavirus (HPV) structural antigens and DNA types in inverted papillomas and squamous cell carcinomas of the nasal cavities and paranasal sinuses

To assess the suggested etiological role of human papillomavirus (HPV), biopsies from 14 patients operated on for an inverted papilloma (11 cases) and squamous cell carcinoma (3 cases) of the nasal cavity and paranasal sinuses were analysed for light microscopical evidence of HPV, by indirect immunoperoxidase (IP-PAP) to demonstrate HPV structural proteins, and using in situ DNA-hybridization to disclose the DNA of HPV types 6, 11 and 16. The majority of the inverted papillomas contained areas of metaplastic squamous cells, including koilocytes as well as dysplastic changes consistent with intra-epithelial neoplasia as described in uterine cervix. In 3 patients, frankly invasive squamous cell carcinomas were found, originating from dysplastic squamous epithelium. Of the 14 lesions, 7 (50%) expressed HPV antigens, usually confined to only a few cells close to the surface of the epithelium. None of the malignant lesions expressed HPV antigens. In situ DNA-hybridization disclosed HPV 11 DNA alone in 5 lesions, but none of the lesions contained HPV 6 DNA. HPV 16 DNA was found in 2 lesions as a single HPV type, and in 3 other lesions concomitant with HPV 11. All three carcinomas contained HPV 16 DNA. The HPV DNA distribution proved to be different from that found in the genital tract HPV lesions; HPV DNA was less abundant in the nasal papillomas, and it was also found in the basal and suprabasal cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification of human papillomavirus types in male urethral condylomata acuminata by in situ hybridization

An in situ hybridization technique was applied under stringent conditions to paraffin sections of urethral condylomata from male patients to determine the presence of DNA sequences of human papillomavirus (HPV) types 6, 11, 16, and 18. The material consisted of 15 classical condylomata acuminata, two flat condylomata, and five recurrent lesions. HPV DNA sequences could be identified in all 15 condylomata acuminata; in 13 lesions, two types of viral DNA were observed (types 6 and 11 in 12, types 6 and 18 in one). In the remaining two condylomata acuminata, only HPV type 11 was present. One of the two flat condylomata was negative with all the probes, and one was borderline-positive for HPV 6. Four of five recurrent lesions contained the same types of viral DNA as the primary lesions, albeit with slight differences in the intensity of viral expression. One lesion was negative with all probes. We conclude that urethral condylomata in males contain the same types of HPV as seen in other anogenital lesions of both sexes and that infection with two viral types is common. In situ hybridization with HPV DNA probes is applicable to archival material and therefore may prove to be of value in future epidemiologic studies comparing lesions in sexual partners. The determination of viral type may have therapeutic implications.

Detection of low copy human papilloma virus DNA and mRNA in routine paraffin sections of cervix by non-isotopic in situ hybridisation

In analysing human papilloma virus (HPV) infection of the cervix in formalin fixed paraffin sections by non-isotopic in situ hybridisation two main problems were found: detachment of sections from the glass during hybridisation and probe detection; inadequate sensitivity and inability to assess sensitivity of the in situ procedure. The first problem was investigated by assessing the efficiency of various tissue adhesives individually and in combination. The second problem was addressed by optimising conditions for DNA unmasking, hybridisation, and biotinylated probe detection. Sensitivity of the final in situ procedure developed was assessed by using the detection of pHY2.1 repeats as a built-in control. Extrapolation of data showed that less than 10 copies of HPV DNA can be visualised by these procedures. HPV nucleic acid, mainly in the form of DNA, was detected not only in koilocytic nuclei but also in suprabasal cells in condylomas and CIN lesions. HPV mRNA was also visualised in the cytoplasm (and probably also nuclei) of the same cell types. These non-isotopic in situ procedures give results comparable to those obtained with radiolabelled probes, but they are less time consuming and provide better morphological resolution.

Localization of types I, II, and III collagen mRNAs in developing human skeletal tissues by in situ hybridization

Paraffin sections of human skeletal tissues were studied in order to identify cells responsible for production of types I, II, and III collagens by in situ hybridization. Northern hybridization and sequence information were used to select restriction fragments of cDNA clones for the corresponding mRNAs to obtain probes with a minimum of cross-hybridization. The specificity of the probes was proven in hybridizations to sections of developing fingers: osteoblasts and chondrocytes, known to produce only one type of fibrillar collagen each (I and II, respectively) were only recognized by the corresponding cDNA probes. Smooth connective tissues exhibited variable hybridization intensities with types I and III collagen cDNA probes. The technique was used to localize the activity of type II collagen production in the different zones of cartilage during the growth of long bones. Visual inspection and grain counting revealed the highest levels of pro alpha 1(II) collagen mRNAs in chondrocytes of the lower proliferative and upper hypertrophic zones of the growth plate cartilage. This finding was confirmed by Northern blotting of RNAs isolated from epiphyseal (resting) cartilage and from growth zone cartilage. Analysis of the osseochondral junction revealed virtually no overlap between hybridization patterns obtained with probes specific for type I and type II collagen mRNAs. Only a fraction of the chondrocytes in the degenerative zone were recognized by the pro alpha 1(II) collagen cDNA probe, and none by the type I collagen cDNA probe. In the mineralizing zone virtually all cells were recognized by the type I collagen cDNA probe, but only very few scattered cells appeared to contain type II collagen mRNA. These data indicate that in situ hybridization is a valuable tool for identification of connective tissue cells which are actively producing different types of collagens at the various stages of development, differentiation, and growth.

Detection of human papillomavirus DNA in anogenital condylomata in men using in situ DNA hybridisation applied to paraffin sections

An in situ DNA hybridisation method was used to detect human papillomavirus (HPV) DNA (HPV types 6, 11, 16, and 18), and an immunoperoxidase (IP-PAP) method to detect HPV structural protein expression in paraffin sections of biopsy specimens from 133 men treated for penile (in 114 cases) and anal (in 19 cases) warts. The anatomical distribution on the penis of classic condyloma acuminatum and of papular and flat condylomata was practically identical. The gross appearance of the warts did not correlate with their morphology on light microscopy. The detection rate of dysplasia was very different in the three types of lesions (25% in flat, 50% in acuminatum, and 75% in papular warts). Of 133 lesions, 59 (44.4%) contained HPV antigens, their expression being inversely related to the grade of dysplasia; only 17% of HPV 16 lesions had detectable HPV antigen compared with 50% to 67% in lesions of the other three HPV types. HPV 16 and HPV 18 DNA were most commonly (11%) detectable in Bowenoid lesions; however, most of the HPV 16 and 18 positive cases were found among the flat and acuminatum type of lesions. Though the overall detection rate of HPV DNA (76%) did not correlate with the grade of dysplasia, a clear cut association of HPV 16 and HPV 18 with dysplastic lesions was found, none of the HPV 16 and 25% of the HPV 18 positive cases being devoid of concomitant dysplasia. The corresponding figures for HPV 6 and HPV 11 were 59.2% and 68.8%, respectively. The implications of these findings are discussed in terms of epidemiologically established connections between penile and cervical cancer, with special emphasis of the high risk HPV types 16 and 18. The applicability of in situ DNA hybridisation as a powerful tool in the analysis of specific HPV DNA sequences in routinely processed biopsy specimens from these lesions is emphasised.

Detection of human papillomavirus DNA in oral mucosal lesions using in situ DNA-hybridization applied on paraffin sections

The in situ DNA hybridization technique, carried out under stringent conditions, was used to detect human papillomavirus (HPV) DNA of types 6, 11, and 16 in paraffin sections of 32 surgically treated oral mucosal lesions. Expression of HPV structural proteins was analyzed by means of the immunoperoxidase (IP-PAP) method. A total of 10 (31.3%) of the 32 lesions proved to express HPV antigens, which were found in 4 of 7 squamous cell papillomas, in 2 of 2 classic condylomas, in 2 of 10 papillary hyperplasias, and in 2 of 3 leukoplakia lesions. Two of the squamous cell papillomas contained HPV 6 DNA, and 4 additional lesions were positive for HPV 11 DNA. In one of the condylomas, a double infection by HPV 6 and 11 was found, while the second was positive for HPV 11 alone. Both the HPV antigen-positive papillary hyperplasias contained HPV 6 DNA, as did the HPV antigen-positive leukoplakia lesions. Of the latter, one was infected by HPV 6 and 11. DNA of the "high-risk" HPV 16 was contained in two lesions: one lichen planus lesion and one of the two squamous cell carcinomas. The results confirm the previously reported evidence of HPV involvement in oral mucosal lesions. The implications of these findings are discussed in terms of the well-established premalignant character of oral leukoplakia and oral lichen planus, although far less commonly versus leukoplakia, with special emphasis on the discovery of the "high-risk" HPV 16 in the latter as well as in oral cancer.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of human papillomavirus DNA by the nucleic acid sandwich hybridization method from cervical scraping

Cervical scrapes collected from 100 consecutive patients participating in a prospective follow-up study for cervical human papillomavirus (HPV) infections were tested for the presence of HPV 11 DNA by the nucleic acid sandwich hybridization method, which allows testing the specimens in a crude form. Part of each specimen was processed through phenol extraction and DNA purification to a dot blot hybridization assay. The dot blots were serially hybridized with HPV 6, 11, 16, and 18 probes as well as with an Alu-repeat probe to estimate the number of cells in the specimen. In PAP smears, HPV-infection was suspected in 63 patients whereas in 37 patients the smear was negative. In the first group, the dot blot assay revealed three cases of HPV 11, two of HPV 16, and one of HPV 18 infection. In the second group with normal PAP smear, one additional HPV 18 infection was found. The sandwich hybridization assay detected 5 HPV 11 infections, including the three mentioned above. All HPV DNA-positive samples contained at least 1.6 X 10(6) cells. Since we considered this a prerequisite for successful diagnosis, only 25 specimens in the first group and 15 in the second were adequate specimens. Thus the HPV-DNA detection rate was 32% (8/25) in the first group and 1/15 in the second. This study demonstrates that sandwich hybridization, detecting 1-3 X 10(5) HPV 11 molecules is a reliable diagnostic method. Cervical scrape is a valuable alternative to punch biopsy, but the number of cells collected is critical for the outcome of the assay.

An improved in situ DNA hybridization protocol for detection of human papillomavirus (HPV) DNA sequences in paraffin-embedded biopsies

In situ DNA hybridization is becoming rapidly an important technique for detection and typing of human papillomaviruses (HPV) in epithelial lesions, some of which (those due to HPV 16, 18 and 31) seem to possess an increased risk for progression into an invasive squamous cell carcinoma. An improved in situ DNA hybridization technique (Technique II) was described, and the results obtained in a series of cervical and penile HPV lesions were compared with those given by the in situ hybridization technique (Technique I) previously used in our laboratory. Special emphasis was made to increase the sensitivity with three basic alterations of the hybridization protocol; omission of the 0.2 N HCl wash, use of increased proteinase K concentration (from 50 micrograms/ml to 1 mg/ml), and elevated denaturation temperature (obtained by a heating block instead of an incubator). Poly-D-lysine as a slide-coating medium was replaced by Kodak Photo-Flo 200 to improve the attachment of the tissue sections on the slides. Identical HPV DNA types were discovered by the two hybridization techniques. The attachment of the tissue sections was equal on the slides coated with either poly-D-lysine or Kodak Photo-Flo 200, and the latter did not interfere with the sensitivity of in situ hybridization. The hybridization signals for HPV DNA were weak or moderate in 15/16 lesions with Technique I, but intense in 10/16 lesions with Technique II (P less than 0.001). Furthermore, the resolution of Technique II seemed to be superior to that of Technique I, while being capable of disclosing HPV DNA in the intermediate cell layers (P less than 0.001) and in basal/parabasal cell layers (P less than 0.025) of both the cervical and penile lesions. The discovery of HPV DNA in the parabasal cells provides important clues to the understanding of the biology of HPV infection in the squamous epithelium, and makes this improved in situ DNA hybridization technique invaluable in assessing the lesions, where low copy numbers of HPV are to be expected.