妊娠期人乳头瘤病毒的感染状况及母婴传播的研究

应用聚合酶链反应检测孕妇尖锐湿疣（ＣＡ）组织、无ＣＡ孕妇宫颈分泌物、外周血及羊水、新生儿咽分泌物、脐血中人乳头瘤病毒（ＨＰＶ）感染及母婴传播。结果表明：ＣＡ组织中ＨＰＶＤＮＡ阳性率为９０．３２％，以ＨＰＶ６／１１型为主；无ＣＡ孕妇宫颈分泌物中ＨＰＶＤＮＡ阳性率为３５．７１％，以ＨＰＶ１６／１８型为主；孕妇血中ＨＰＶＤＮＡ阳性率为５７．６９％；母婴间经产道垂直传播率为４４．４４％，血性经胎盘传播传播率为６０％。说明ＨＰＶ不仅存在于ＣＡ组织中，还存在于无ＣＡ孕妇生殖道及外周血中，母婴间传播途径除产道外，还有胎盘传播     

Immunophenotypic and viral (human papillomavirus) correlates of vulvar seborrheic keratosis

Human papillomavirus (HPV) infections of the genital mucosa classically present as warts (condylomata) and are traditionally defined by the presence of viral cytopathic effect (koilocytosis). In recent years, HPV has been detected in vulvar epithelial changes lacking koilocytosis, including squamous papillomas and lesions closely resembling seborrheic keratosis (SK). The purpose of this study was to determine the frequency and type of HPV associated with vulvar SK (VSK) and to compare expression of biomarkers (p16, Mib-1, and cyclin E) in these lesions. Sixty-seven biopsy specimens, including 25 VSKs, 10 nondiagnostic vulvar acanthoses, 12 fibroepithelial polyps (FEPs), and 20 nongenital cutaneous SKs (CSKs), were studied. Biopsy specimens were typed for HPV by polymerase chain reaction and immunostained with Mib-1, cyclin E, and p16(INK4) antibodies. Eighteen of 25 VSKs (72%), 0 of 10 nondiagnostic vulvar acanthuses (0%; P = 0.0001), 2 of 12 FEPs (16.7%; P = 0.004), and 3 of 20 CSKs (15%; P = 0.0002) scored HPV positive. Increased Mib-1 staining was significantly more common in VSKs than in other vulvar lesions, but not in CSKs; increased p16 and cyclin E staining was not more common. VSKs are morphologically and immunophenotypically similar to CSKs but distinct by their association with HPV. Unlike the cervix, p16 and cyclin E will not consistently distinguish VSKs from HPV-negative lesions due to underexpression in low-risk HPV infections (p16) and less-restricted expression in vulvar lesions (cyclin E). Whether CSKs are associated with other forms of HPV infection remains to be determined.     

Characterization of human papillomavirus infection in north Taiwan

The detection of human papillomavirus (HPV) is very important for the evaluation of preventative strategies for cervical cancer. The major objective of this study was to characterize the prevalence of different genotypes of HPV in north Taiwan to contribute to the epidemiological knowledge of HPV infections. Papanicolaou (Pap) cervical smears were collected from 10,543 women aged between 14 and 87 years. The polymerase chain reaction (PCR) and DNA array hybridization techniques were used to genotype 51 different HPV strains. HPV was detected in 1,577 women, which gave an overall HPV prevalence rate of 15%. Forty‐eight different genotypes were found in these patients, which included 9.7% that were high‐risk HPV (HR‐HPV) genotypes. The most common types of HR‐HPV in patients, in descending order of frequency, were HPV 52, 16, 58, 56, 39, 51, 18, 68, 31, 33, 59, 45, and 35. HPV 52 was the most frequent type in every age group. The four most common HR‐HPV types were found in 56.6% of the patients infected with HR‐HPV. In cases that were infected with multiple HPV genotypes, 69.2% had at least one HR‐HPV genotype. The rate of infection with HR‐HPV was higher in the younger age groups than the older ones. In conclusion, 48 HPV genotypes were identified from a large study of cervical screening samples and the prevalence of HPV genotypes in different age groups was very diverse. The formulation of a public health strategy for HPV vaccination should take into account the prevalence of various HR‐HPV/LR‐HPV genotypes. J. Med. Virol. 82:1416–1423, 2010. © 2010 Wiley‐Liss, Inc.     

Importance of specimen type in detecting human papillomavirus DNA from the female genital tract

HPV testing is a valuable tool in cervical cancer screening and efficacy assessment of HPV vaccines. Concordance of specimens from three sites for detection of HPV DNA in the female genital tract was evaluated. At a single visit, the following specimens were collected: an endo‐ecto‐cervical swab (EEC), labial/vulvar/perineal/perianal swab (LVPP) and cervicovaginal lavage (CVL). Specimens were evaluated with HPV6, HPV11, HPV16, and HPV18 type‐ and gene‐specific PCR assays. Of the 898 women evaluated at baseline, 232 were HPV PCR positive in at least one specimen. Of these, for HPV6, HPV11, HPV16, and HPV18, respectively, throughout: (a) 70.4%, 40.0%, 65.3%, and 64.1% tested three‐site positive; (b) 13.6%, 30.0%, 19.7%, and 18.8% tested two‐site positive; and (c) 16.4%, 30.0%, 15.0%, and 17.2% tested single‐site positive. For patients who tested single‐site positive for HPV6, HPV11, HPV16, or HPV18, respectively, the specimen was: LVPP in 92.3%, 33.3%, 68.2%, and 72.7%; EEC in 0.0%, 33.3%, 18.2%, and 9.1%; and CVL in 7.7%, 33.3%, 13.6%, and 18.2%. Combining results of swab specimens together increases detection of HPV6, HPV11, HPV16, and HPV 18, respectively, to 98.7%, 90.0%, 97.9%, and 96.9%. HPV DNA is detectable from all three sites using type‐specific PCR assays; most women who tested positive for a given HPV type were positive for that type in all three specimens. J. Med. Virol. 81:1620–1626, 2009. © 2009 Wiley‐Liss, Inc.     

宫颈病变程度与人类乳头瘤病毒(16、18型)负荷的关系

目的探讨宫颈病变程度与人类乳头状瘤病毒(HPV)16、18型负荷的关系。方法采用实时荧光定量聚合酶链反应(FQ-PCR)方法,检测宫颈不同病变活检组织及石蜡包埋标本中HPV16、18型感染状况。结果正常宫颈上皮感染HPV16、18型阳性率为3%,CINⅠ、Ⅱ、Ⅲ级和宫颈癌感染HPV16、18阳性率分别为45.7%,69.5%,72.2%和74.6%。正常宫颈与CIN,宫颈癌HPV16、18阳性率差异有极显著性(P<0.0001)。宫颈糜烂(Ⅰ°、Ⅱ°、Ⅲ°),CIN(Ⅰ、Ⅱ、Ⅲ级)及鳞癌HPV16、18阳性标本平均拷贝数分别为:3.58×103、1.80×105、1.19×107,随着病变程度加重而逐渐增加,差异有极显著性(P<0.0001)。结论宫颈病变程度与HPV16、18型负荷呈正相关。对宫颈病变组织标本行HPV16、18型检测,对判断宫颈病变发展趋势,积极处理癌前病变,阻断病程、预防宫颈癌的发生将起到重要作用。     

Human papillomavirus infection in actinic keratosis and bowen's disease: comparative study with expression of cell-cycle regulatory proteins p21(Waf1/Cip1), p53, PCNA, Ki-67, and Bcl-2 in positive and negative lesions

We examined the presence of human papillomavirus (HPV) DNA in tissues of premalignant skin lesions, i.e., actinic keratosis (n = 13) and Bowen's disease (n = 62), taken from 69 Japanese immunocompetent and renal transplant recipient patients. Detection and typing of HPV DNA were performed using polymerase chain reaction (PCR) and sequence analysis or restriction fragment length polymorphism (RFLP) analysis, respectively. The positivity rates of HPV DNA in tissues of actinic keratosis and Bowen's disease were 77% and 65%, respectively. Twenty-seven HPV types were detected in 50 (67%) premalignant skin lesions, in which Z95963 (accession no. in the EMBL Databank), Z95968, AJ010823, and AJ000151 have been described as partial sequences of unknown HPV types. Furthermore, 2 unknown types, HPVX1 and HPVX2, were found in specimens of actinic keratosis. Sequence analysis showed that HPVX1 is related to HPV-37 (86.1% sequence homology) and that HPVX2 is related to HPV-38 (79.7%). These results indicate that various mucosal and epidermodysplasia verruciformis-related HPV types are associated with the pathogenesis of actinic keratosis and Bowen's disease. In addition, 24 specimens of HPV-positive or HPV-negative premalignant skin lesions were examined immunohistochemically for proliferating cells to determine biological differences between HPV-positive and HPV-negative lesions. Immunohistochemistry for p21(Waf1/Cip1), p53, proliferating cell nuclear antigen (PCNA), Ki-67, and Bcl-2 revealed that there was no significant difference in the cell proliferation activity between HPV-positive and HPV-negative lesions, suggesting that HPV infection alone does not induce cell proliferation in those lesions.     

Human papillomavirus 6, 11, and 16 in laryngeal papillomas.

Twenty-seven cases of benign laryngeal papillomas, both single and multiple variants, were analysed for human papillomavirus (HPV) by DNA slot-blot hybridization chiefly to determine the pattern of infection in Hong Kong Chinese. DNA was extracted from paraffin blocks of formalin-fixed tissue and probed separately for HPV 6, 11, 16, and 18. Sixteen cases (59 per cent) showed the presence of at least one of these four HPV genomes. Thirteen cases (48 per cent) were positive for HPV 11 only. Three other cases (11 per cent) showed triple positivity for HPV 6, 11, and 16. None were positive for HPV 18. The predominance of HPV 11 infection contrasts with other series which have shown either an almost equal distribution of HPV 6 and 11 or a predominance of HPV 6. The finding of HPV 16 in three cases was unexpected. Using the polymerase chain reaction (PCR) with primers complementary to the upstream regulatory region of the HPV 16 viral DNA, the presence of HPV 16 genome was confirmed in all three cases. As the number of HPV 16-positive cases in this study is small, analysis of more cases using fresh biopsy material and a wider range of HPV type-specific PCR primers is warranted to determine the relative incidence of HPV subtypes in these benign laryngeal papillomas.     

Analytical performance of a low-cost multiplex polymerase chain reaction human papillomavirus genotyping assay for use in Sub-Saharan Africa

We have tested a multiplex polymerase chain reaction (PCR) human papillomavirus (HPV) genotyping assay to fill the need for rapid and low-cost HPV detection in Sub-Saharan Africa. This method allows high throughput genotyping and simultaneous detection of 14 high-risk and two low-risk HPV types, by PCR amplification of HPV DNAs in a single reaction tube. In this study, we describe stepwise experiments to validate the multiplex HPV PCR assay for determination of HPV genotypes from 104 cervical brush samples from Tanzanian women. Assay performance was evaluated by determination of intra-laboratory reproducibility, sensitivity, and specificity. Further performance was assessed by comparison with the widely accepted and validated HPV My09/My11 amplification and hybridization assay. Statistics; the Cohen kappa (κ) and McNemar P values were used to analyze interobserver and intermethod agreement. Overall concordance between the multiplex and line blot hybridization assays was 99% (per sample) with a κ value equal to 0.95; and 96.49% (per detection event) with a κ value of 0.92. Interobserver reproducibility of the assay per sample was 95.76% with κ of 0.91. These results demonstrate that the multiplex HPV PCR assay has high analytical sensitivity and specificity in detecting as many as 16 different HPV genotypes and that its simplicity and low cost makes it well suited for sub-Saharan Africa.     

人疱疹病毒6型感染与神经胶质瘤关系的初步研究

目的探讨人疱疹病毒6型（human herpesvirus-6,HHV-6）感染与神经胶质瘤的关系。方法将辽宁省肿瘤医院神经外科2011年6月-2013年5月收治的神经胶质瘤患者45例纳入病例组,将同期该医院收治且已排除神经胶质瘤的脑外伤患者45例作为对照组。分别采用巢式聚合酶链式反应（nested polymerase chain reaction,Nested—PCR）法检测两组研究对象人病变脑组织样本中HHV-6序列;采用免疫组化染色法检测两组研究对象人病变脑组织样本中HHV-6抗原的表达。结果病例组HHV石DNA阳性率为31．11％,对照组HHV-6DNA阳性率为6．67％（χ2=8．755,P=0．003）。病例组HHV-6早期抗原041表达阳性率为22．22％,对照组HHV-6早期抗原p41表达阳性率为0．00％（χ2=11．250,P=0．001）。病例组HHV-6DNA阳性率、HHV-6抗原阳性率均高于对照组,组间差异有统计学意义（P〈0．05）。结论神经胶质瘤患者和非神经胶质瘤脑外伤患者病变脑组织中HHV石感染率有差异,据此推断HHV-6感染在神经胶质瘤的发生和发展过程中起到一定的作用。     

人乳头瘤病毒11型DNA中CpG基序甲基化状态分析及生物活性的研究

目的　对人乳头瘤病毒 11型全核苷酸序列的CpG基序 (CpGmotifs)进行分析 ,为阐明尖锐湿疣的发病机制和提高DNA疫苗的效能奠定理论基础。方法　对从pBR32 2 HPV11重组质粒上酶切下来的HPV11全长DNA进行计算机分析 ,包括分类、计数和定位 ;并用限制性内切酶PCR法分析HPV11DNA中CpG基序的甲基化状态 ,即分别用甲基化敏感的限制性内切酶AccⅡ、HaeⅡ和HpaⅡ对HPV11DNA进行酶切消化 ,再以HpaⅡ切割位点侧翼序列为引物 ,以HpaⅡ酶切产物为模板 ,用聚合酶链反应 (PCR)扩增HPV11DNA片断 ,并用HPV11DNA刺激表达有pCIneo TLR9的HEK2 93细胞 ,ELISA法检测TNF al pha、IFN alpha和IL 12的分泌。结果　CpG的“C”的侧翼为两个嘌呤 ,“G”的侧翼为两个嘧啶 ,在HPV11中共 14个。HPV11全基因组被AccⅡ切成 2个片断、被HaeⅡ切成 3个片断、被HpaⅡ切成 5个片断 ,而且以HpaⅡ酶切产物为模板进行PCR扩增 ,未能得到相应的片断。HPV 11DNA刺激有人TLR9表达的HEK2 93细胞后能检测到TNF alpha、IFN alpha和IL 12的分泌。结论　乳头瘤病毒 11型DNA中含有GACGTT等非甲基化的CpG基序 ,而且具有免疫原性     

Cutaneous human papillomavirus types detected on the surface of male external genital lesions: A case series within the HPV Infection in Men Study

BackgroundCutaneous human papillomaviruses (HPVs) may be associated with cutaneous epithelial lesions and non-melanoma skin cancers. No study has systematically evaluated the presence of genus beta [β]-HPV in male genital skin or external genital lesions (EGLs)ObjectivesTo examine cutaneous β-HPV types detected on the surface of EGLs in men and describe their presence prior to EGL development.Study designA retrospective case series was conducted among 69 men with pathologically confirmed EGLs (n = 72) who participated in the HPV Infection in Men Study. Archived exfoliated cells collected from the surface of each EGL and normal genital skin specimens 6–12 months preceding EGL development were tested for β-HPV DNA using a type-specific multiplex genotyping assay.Resultsβ-HPV DNA was detected on 61.1% of all EGLs, with types 38 (16.7%), 5 (15.3%), and 12 (12.5%) most commonly identified. HPV prevalence differed across pathological diagnoses, with the largest number of β-HPV types detected on condylomas. Most β-HPV types were detected on normal genital skin prior to EGL development, though the prevalence was lower on EGLs compared to preceding normal genital skin.ConclusionsEGLs and the normal genital skin of men harbor a large number of β-HPV types; however, it appears that β-HPVs are unrelated to EGL development in men. Despite evidence to support a causal role in skin carcinogenesis at UVR-exposed sites, cutaneous HPV appears unlikely to cause disease at the UVR-unexposed genitals.     

Development and evaluation of a PCR and mass spectroscopy (PCR–MS)-based method for quantitative, type-specific detection of human papillomavirus

Knowledge of the central role of high-risk human papillomavirus (HPV) in cervical carcinogenesis, coupled with an emerging need to monitor the efficacy of newly introduced HPV vaccines, warrant development and evaluation of type-specific, quantitative HPV detection methods. In the present study, a prototype PCR and mass spectroscopy (PCR–MS)-based method to detect and quantitate 13 high-risk HPV types is compared to the Hybrid Capture 2 High-Risk HPV DNA test (HC2; Digene Corp., Gaithersburg, MD) in 199 cervical scraping samples and to DNA sequencing in 77 cervical tumor samples. High-risk HPV types were detected in 76/77 (98.7%) cervical tumor samples by PCR–MS. Degenerate and type-specific sequencing confirmed the types detected by PCR–MS. In 199 cervical scraping samples, all 13 HPV types were detected by PCR–MS. Eighteen (14.5%) of 124 cervical scraping samples that were positive for high-risk HPV by HC2 were negative by PCR–MS. In all these cases, degenerate DNA sequencing failed to detect any of the 13 high-risk HPV types. Nearly half (46.7%) of the 75 cervical scraping samples that were negative for high-risk HPV by the HC2 assay were positive by PCR–MS. Type-specific sequencing in a subset of these samples confirmed the HPV type detected by PCR–MS. Quantitative PCR–MS results demonstrated that 11/75 (14.7%) samples contained as much HPV copies/cell as HC2-positive samples. These findings suggest that this prototype PCR–MS assay performs at least as well as HC2 for HPV detection, while offering the additional, unique advantages of type-specific identification and quantitation. Further validation work is underway to define clinically meaningful HPV detection thresholds and to evaluate the potential clinical application of future generations of the PCR–MS assay.     

Multiple Skin Cancers in a Renal Transplant Recipient: A Patient Report with Analyses of Human Papillomavirus and Human Polyomavirus Infection

Skin cancer is an important complication in renal transplant recipients. Associations of transplant-related skin tumor with ultraviolet radiation, age at transplantation, type of immunosuppressant drug administered, and viral infection have been reported; however, the details remain unclear. We report a 61-year-old man who had underwent renal transplantation at 38 years of age and developed multiple skin tumors or squamous cell carcinomas (SCCs). Polymerase chain reaction (PCR) analyses of the patient’s 12 tumors for viral DNAs of cutaneous or mucosal human papillomavirus (HPV) and 6 human polyomaviruses (MCPyV, trichodysplasia spinulosa-associated, BK, JC, KI and WU polyomaviruses) only detected cutaneous HPV-DNA in only 5 of the tumors; no other viruses were detected. Real-time PCR showed high loads of cutaneous HPV in 3 SCCs and very low loads of MCPyV in 9. Immunohistochemistry revealed no tumor cell expression for MCPyV-large T-antigen or mucosal HPV. Our report not only reconfirmed the association of cutaneous HPV5 with skin cancer in renal transplant recipients in previous studies but also showed no relevant association of 6 human polyomaviruses and mucosal HPV with skin tumors.     

A PCR based DNA hybridisation capture system for the detection of human cytomegalovirus. A comparative study with other identification methods

A simple, sensitive and specific colourimetric hybridisation method for the detection of HCMV DNA in clinical specimens is described. This method combines a PCR assay with a sensitive sandwich hybridisation assay. It relies on the use of a specific capture probe linked covalently to polystyrene microplates and a specific polybiotinylated detection probe. Amplified DNA fragments, sandwiched between these two probes, are detected by an enzymatic colour reaction. This PCR-based colourimetric hybridisation method was compared with other known HCMV detection methods. Clinical specimens (n=145, corresponding to 106 patients) were tested by both a nested PCR assay and this colourimetric hybridisation method; and by either the culture method or the pp65 antigenaemia test depending on the type of sample used. The results showed that the PCR-based hybridisation method has a specificity similar to tissue culture, known as the conventional gold standard method, and could be used for the examination of the clinical specimens.     

A rapid and reliable PCR method for genotyping the ABO blood group. II: A2 and O2 alleles

PCR permits direct genotyping of individuals at the ABO locus. Several methods have been reported for genotyping ABO that rely on differentiating the A, B, and O alleles at specific base substitutions. However, the O allele as defined by serology comprises at least two alleles (O¹ and O²) at the molecular level, and most current ABO genotyping methods only take into account the O¹ allele. Determining the presence of the O² allele is critical, as this not-infrequent allele would be mistyped as an A or a B allele by standard PCR typing methods. Furthermore, none of the methods to date distinguish between the A¹ and A² alleles, even though 10% of all white persons are blood group A². We have developed a method for genotyping the ABO locus that takes the O² and A² alleles into account. Typing for A² and O² by diagnostic restriction enzyme digestion is a sensitive, nonradioactive assay that provides a convenient method useful for forensic and paternity testing and for clarifying anomalous serological results. © 1996 Wiley-Liss, Inc.     

HPV高危型别检测联合细胞学检查对宫颈病变筛查的研究

目的 研究人乳头瘤病毒HPV高危型别检测联合液基薄层细胞学检查（TCT）及阴道镜检查对宫颈癌及癌前病变筛查的诊断价值。方法 对1375例宫颈组织细胞样本进行HPV高危型别检测,对其中阳性样本进行TCT检查,有宫颈上皮内瘤变者（CIN）行阴道镜下活检病理组织学确诊。HPV高危型别检测采用双色荧光定量PCR方法进行8种高危型HPV DNA（主要高危型：HPV16,18,45,31）和次要高危型（HPV33,52,58,67）分型及病毒载量检测。结果 1375例样本高危型HPV DNA检测结果为阳性256例,阳性率为18.62％;TCT结果为WNL的样本高危型HPV的感染率为16.41％ （42/256）;TCT结果为ASCUS以上的样本高危型HPV的感染率为83.59％（ 214/256）。HPV各型别的病毒载量在TCT结果为WNL、ASCUS及LSIL/HSIL/SCC之间差异无统计学意义（P＞0.5）。TCT与阴道镜的阳性符合率分别为WNL-正常或炎症92.86％（ 39/42）,LISL-CIN I 81.36％（48/59）,HSIL-CIN Ⅱ＆Ⅲ 85.19％ （23/27）,SCC-宫颈癌9/10。结论 HPV高危型别检测联合TCT技术及阴道镜检查能显著提高宫颈病变的阳性检出率,可作为宫颈癌及宫颈上皮内瘤变（ CIN）筛查的可靠早期诊断方法,具有重要临床应用价值。     

120例儿科患儿微小病毒B19感染的近期研究

目的 探讨人类微小病毒B19（HPVB19）在儿科疾病中的感染状况.方法 应用巢式聚合酶链反应的方法（PCR）以及ELISA法,对120例患儿（观察组）及40例随机挑选本院门诊健康体检儿童（对照组）血浆中微小病毒B19-DNA以及B19-VP2-IgM检测.结果 120例患儿（观察组）B19-DNA检测总阳性检出率为31.7%（38/120）,40例健康儿童（对照组）B19-DNA检测均为阴性,两组比较有显著差别（P＜0.005）.其中特发性血小板减少性紫癜（ITP）和心肌炎阳性检出率最高,分别为40%（12/30）和37.1%（13/35）.120例患儿（观察组）B19-VP2- IgM总阳性检出率31.7% （38/120）,40例健康儿童（对照组）B19-DNA检测均为阴性,两组比较有显著差别（P＜0.005）,B19 DNA和B19 VP2 IgM一致率为100%.40例健康儿童（对照组）B19-VP2- IgM均为阴性,两组比较有显著差别（P＜0.005）.结论 儿童对B19有较高的感染率,尤其ITP和心肌炎患儿与B19感染关系更为密切.     

A high frequency of human papillomavirus DNA sequences in cervical carcinomas of Indian women as revealed by Southern blot hybridization and polymerase chain reaction.

Ninety-six colposcopically directed biopsies from squamous epithelial carcinoma of the uterine cervix and 22 age-matched normal control biopsy specimens were examined by both Southern blot hybridization and polymerase chain reaction (PCR) for the presence of different human papillomavirus (HPV) DNA types. Cancer of the uterine cervix, which is the most common malignant disease in Indian women, showed a high frequency (98%) of HPV as compared to those reported from other parts of the world. HPV type 16 was found to be the dominant (64%) type while the frequency of HPV type 18 was very low (3%). On individual typing of HPV, no biopsy was found to contain any other known HPV types under stringent conditions of hybridization except a single case of HPV type 11. Only one case of double infection with HPV types 16 and 18 was recorded. Under low stringency conditions of hybridization with a mixed probe of HPV types 16 and 18, 29 additional biopsies were found to be positive. Southern blot hybridization alone detected HPV DNA in 92% of the cases but none in the controls. By PCR, six (6.25%) more cases and four (18.18%) healthy women were found to be positive for HPVs. Analysis of the physical state of HPV 16 indicated integration in about 70% of carcinoma cases while 30% of them were in episomal form. The findings suggest that infection with HPV is an important etiologic factor for the development of cervical cancer, that a number of such tumours may arise without HPV infection, and that integration of the viral DNA into host genome is not always essential for malignant progression.(ABSTRACT TRUNCATED AT 250 WORDS)