宫颈癌中抑癌基因FHIT表达与HPV16基因状态

目的:探讨抑癌基因FHIT表达及人乳头瘤病毒16(HPV16)的基因型整合状态在宫颈癌发生发展中的作用及相关性。方法:选取柳州市人民医院2013年6月至2014年12月收治的42例宫颈癌、55例宫颈上皮内瘤样病变(CIN)和20例宫颈正常组织的患者,免疫组化法检测宫颈组织中FHIT蛋白表达;多重PCR法检测HPV16 E2/E7表达。结果:FHIT蛋白的总阳性表达率为57.26%(67/117),正常宫颈组织、CINⅠ、CINⅡ、CINⅢ和宫颈癌中FHIT蛋白阳性率分别为85.00%、80.00%、75.00%、60.00%和26.19%。随着宫颈病变加重,FHIT蛋白阳性表达率下降,组间差异有统计学意义(χ~2=7.335;P=0.003)。117例单纯HPV16阳性标本HPV16总整合率为81.20%,正常宫颈组织、CINⅠ、CINⅡ、CINⅢ和宫颈癌中整合率分别为60.00%、66.67%、75.00%、95.00%和92.86%;随病变加重,整合率增强,组间差异有统计学意义(χ~2=5.713,P=0.003);FHIT蛋白阳性表达在不同HPV16整合时不同,差异有统计学意义(χ~2=11.989,P=0.000)。结论:HPV16基因整合可能通过诱导FHIT基因低表达从而促使宫颈癌发生发展。     

FHIT基因、HPV16E6的表达与宫颈鳞癌发病的相关性研究

目的：探讨抑癌基因脆性组氨酸三联（fragile histine triad,FHIT）基因、人乳头瘤病毒16E6（HPV16E6）蛋白在宫颈鳞癌中的表达及其相互关系。方法：应用免疫组织化学链霉菌抗生物素蛋白-过氧化物酶连接（SP）法观察40例宫颈鳞癌、30例宫颈上皮内瘤样病变（CIN）和30例正常宫颈组织中FHIT基因、HPV16E6的表达。结果：FHIT基因在正常宫颈组织、CIN和宫颈鳞癌组织中的阳性表达率分别为96.7%,66.7%和30.0%,各组间阳性等级表达比较差异有统计学意义（χ2=43.595,P〈0.001）。FHIT基因阳性表达在宫颈鳞癌病理分级、临床分期中的比较,差异无统计学意义（χ2分别为3.378和3.315,均P〉0.05）。HPV16E6在正常宫颈组织、CIN和宫颈鳞癌组织中的阳性表达率分别为13.3%,53.3%和82.5%,各组间阳性等级表达比较差异有统计学意义（χ2=32.538,P〈0.001）。HPV16E6蛋白阳性表达在宫颈鳞癌病理分级、临床分期中的比较,差异无统计学意义（χ2分别为0.231和1.399,均P〉0.05）。结论：宫颈鳞癌中FHIT基因表达减少或缺失,以及HPV16E6的高检出率,提示二者在宫颈鳞癌的发生发展中起重要作用,可能是宫颈鳞癌发病机制之一。通过对FHIT基因和HPV16E6蛋白的致病机制以及相互影响的研究,有助于揭示宫颈癌发病机制,二者有可能用于临床宫颈癌诊断、预防和基因治疗。     

宫颈上皮内瘤变及早期宫颈癌组织中P16、HPV L-1壳蛋白的表达及与HR-HPV载量相关性研究

目的:探讨宫颈上皮内瘤变(CIN)及早期宫颈癌组织中P16、HPV L-1壳蛋白的表达及与高危型人乳头瘤病毒(HR-HPV)载量的相关性。方法:分别采用免疫组化法和第二代杂交捕获法(hybrid captureⅡ,HC-2)检测26例慢性宫颈炎组织、83例低度鳞状上皮内病变(LSIL)(CINⅠ83例)、109例高度鳞状上皮内病变(HSIL)(CINⅡ49例,CINⅢ60例)、11例早期宫颈鳞癌组织中P16蛋白、HPV L-1壳蛋白的表达及HR-HPV载量,并分析其相关性。结果:1在宫颈癌前病变中随病变级别增高,HR-HPV阳性率增加,差异有统计学意义(P0.01)。各组织学分级中病毒载量分布差异有统计学意义,HSIL(44.95%)及早期宫颈癌组织(63.64%)中皆以低病毒载量(1~100 RLU/CO)为主。从慢性宫颈炎、LSIL、HSIL到早期宫颈癌,P16蛋白阳性表达率分别为11.54%(3/26),55.42%(46/83),85.32%(93/109),100.00%(11/11),差异有统计学意义(P0.01);L-1壳蛋白阳性率分别为15.38%(4/26),28.92%(24/83),14.68%(16/109),0.00%(0/11),差异有统计学意义(P0.05)。2229例宫颈组织中,随HPV载量增加,P16蛋白表达增强;L-1壳蛋白阳性表达率增加,差异有统计学意义(P0.01)。3在慢性宫颈炎组中,P16蛋白阳性表达与HPV载量呈正相关(r=0.491,P0.05)。在LSIL组中,P16蛋白与HPV载量(r=0.459,P0.01)及L1壳蛋白表达(r=0.297,P0.01)皆呈正相关。4在HSIL及早期宫颈癌组中,P16蛋白、L-1壳蛋白表达与HPV载量三者之间无明显相关性(P0.05)。结论:P16、HPV L-1壳蛋白异常表达是宫颈癌前病变发生发展的早期分子事件,对判断CINⅠ有参考价值,可能比HR-HPV载量更具有预测价值。     

HPV16/18E6蛋白和PKR/p-PKR在宫颈病变的表达及意义

目的:探讨宫颈病变组织HPV16/18感染对蛋白激酶R(PKR)激活的影响及两者在宫颈癌形成、演进过程中的作用和对宫颈癌患者预后的影响。方法:用免疫组化SP法检测HPV16/18型E6蛋白(E6)、PKR、磷酸化型PKR(p-PKR)在63例宫颈癌、114例宫颈上皮内瘤样病变(CINⅠ~Ⅲ)、15例正常宫颈组织的表达。结果:E6蛋白与PKR在各组的阳性表达率与宫颈病变级别呈正相关(P<0.05,P<0.05),E6蛋白与PKR在各组的阳性表达率呈正相关(P<0.05);宫颈癌组PKR阳性表达率明显高于p-PKR(P<0.01);E6、PKR阳性表达率与肿瘤大小有关(P<0.05,P<0.05);宫颈癌患者病情进展与临床分期显著相关(P<0.01),病情进展与E6、p-PKR阳性表达率相关(P<0.05,P<0.05)。结论:HPV16/18感染可阻碍PKR激活,突破机体防御HPV16/18感染的机制,在宫颈癌的发生及演进过程中可能起了重要作用,对宫颈癌患者预后不利;p-PKR能抑制宫颈癌患者病情进展,可能改善其预后。     

HPV16基因整合与FHIT蛋白缺失在宫颈癌变中的作用

目的 探讨HPV16的基因型整合状态及FHIT基因缺失在宫颈癌发生发展中的作用及相关性。方法选取44例宫颈癌、58例宫颈上皮内瘤样病变(CIN)和20例宫颈正常组织的患者,免疫组化检测宫颈FHIT蛋白的表达;并用多重PCR法检测HPV16 E2/E7表达。结果 122例单一HPV16阳性标本HPV16总整合率为78.69%,在正常宫颈组织、CIN1、CIN2、CIN3和宫颈癌中整合率分别为60.00%、66.67%、75.00%、86.96%和88.63%,随病变加重,整合率增强,组间差异有统计学意义(P0.05);FHIT蛋白的总缺失率为43.44%,FHIT蛋白在正常宫颈组织、CIN1、CIN2、CIN3和宫颈癌中的缺失率分别为15.00%、20.00%、25.00%、43.48%和72.73%。FHIT蛋白的缺失率,随病变加重,缺失率增高,组间差异有统计学意义(P0.05)。FHIT蛋白缺失在不同HPV16整合时不同,差异有统计学意义(P0.05)。结论 HPV16基因整合和FHIT蛋白缺失在宫颈癌的发生、发展中起重要作用,HPV16基因整合可能通过诱导FHIT基因低表达从而促使宫颈癌发生发展。     

宫颈癌及癌前病变组织中Notch1及HPV16 E6/E7表达的研究

目的 探讨Notch1受体和人乳头瘤病毒16感染在宫颈癌前病变和宫颈癌发生发展中的作用。方法 采用免疫组化SP法检测18例宫颈上皮内瘤变（cervical intraepithelial neoplasia,CIN）和35例宫颈癌标本中Notch1受体及HPV16E6/E7蛋白的表达,以34例正常宫颈组织及慢性宫颈炎组织作为对照。比较各组间Notch1及HPV16E6/E7表达的差异,并分析Notch1与HPV16E6/E7表达的关系。结果 Notch1蛋白在细胞胞浆、胞核及胞膜中表达,HPV16E6/E7在细胞核中表达。从对照组到CIN组到宫颈癌组,Notch1及HPV16E6/E7的表达均逐渐增强（P〈0.01）。Notch1的阳性表达与宫颈癌不同分期、分化程度、淋巴结是否转移无关（P〉0.05）。在宫颈癌组中Notch1与HPV16E6/E7的表达均呈正相关性（P〈0.01）。结论 Notch1表达与HPV16E6/E7感染可能与CIN及宫颈癌的发生密切相关,两者在宫颈癌的发病机制中可能协同发挥作用。     

HPV16 18 E6蛋白在宫颈脱落细胞中的表达研究

目的 探讨人乳头状瘤病毒(human papillomavirus,HPV)16和(或)18 E6蛋白在宫颈脱落细胞中的表达与宫颈上皮内瘤变(cervical intraepithelial neoplasia,CIN)及宫颈鳞状细胞癌(cervical squamous cell carcinoma,CSCC)的关系.方法 采用免疫印迹(Western blot)方法检测2003年6月至2005年6月中国医科大学第一附属医院CSCC 30例、CIN 52例和16例正常宫颈脱落细胞中HPV16和(或)18 E6蛋白的表达.结果 在上述各组宫颈脱落细胞中HPV16和(或)18 E6表达阳性率分别76.7%(23/30)、51.9%(27/52)和12.5%(2/16);其中在CSCC宫颈脱落细胞中HPV16和(或)18 E6明显高于正常对照组的表达(P＜0.01);CINⅡ、Ⅲ组的表达也显著高于对照组(P＜0.05),而CINⅠ组与正常对照组比较差异无显著性意义(P＞0.05).结论 宫颈脱落细胞标本存在HPV16和(或)18 E6癌基因的表达.宫颈脱落细胞中HPV16和(或)18 E6癌基因的过度表达与CSCC及CINⅡ、Ⅲ密切相关.     

HPV E6/E7 mRNA、p16/Ki67检测在ASCUS中的诊断价值

目的:探讨HPV E6/E7 mRNA、p16/Ki67检测在宫颈细胞学检查为意义不明确的不典型鳞状细胞(ASCUS)中的诊断价值。方法:回顾分析2015年12月至2017年5月在郑州大学第三附属医院就诊的液基薄层细胞学检查(TCT)结果为ASCUS,并行阴道镜下宫颈组织活检的患者200例。应用杂交捕获技术(HC2)和支链DNA技术(b DNA)行HPV DNA、HPV E6/E7 mRNA检测。免疫组化法检测宫颈组织中p16/Ki67表达。结果:宫颈高级别病变组(包括CIN2,CIN3,宫颈癌,简称CIN2+)中p16/Ki67、HPV E6/E7mRNA的阳性率与炎症/CIN1组比较,差异有统计学意义(χ2=31. 952,P=0. 000;χ2=11.231,P=0.001),且p16/Ki67表达与CIN2+具有一致性(kappa=0.400,P=0.000)。炎症/CIN1组中,HPV E6/E7 mRNA检测与p16/Ki67检测结果间的差异有统计学意义(P=0.000),但在CIN2+中两者差异无统计学意义(P=0.375)。ROC曲线分析p16/Ki67检测、HPV E6/E7 mRNA检测诊断CIN2+的准确性分别为(AUC=0.800,0.625),均高于HPV DNA检测(AUC=0.579)。结论:HPV E6/E7 mRNA、p16/Ki67表达与宫颈高级别病变密切相关,HPV E6/E7 mRNA检测可望代替HPV DNA成为分流ASCUS的一种有效手段,而p16/Ki67与宫颈高级别病变显著一致,可辅助用于ASCUS患者宫颈组织的病理诊断。     

Survivin、Bcl-2、HPV 16/18在宫颈上皮内瘤变及宫颈癌中的表达及临床意义

目的:研究Survivin、Bcl-2、HPV 16/18在宫颈上皮内瘤变(CIN)及宫颈癌中的表达,探讨三者与宫颈癌的相关性.方法:采用原位杂交法检测正常宫颈组织(对照组)、CIN(CIN组)和宫颈癌(宫颈癌组)中Survivin mRNA及HPV 16/18 DNA的表达.采用免疫组织化学法检测Bcl-2蛋白在各组中的表达.结果:①Bcl-2蛋白、HPV16/18DNA、Survivin mRNA的阳性率在对照组、CIN组、宫颈癌组中逐渐升高,差异有高度统计学意义(P=0.000).②Bcl-2蛋白和Survivin mRNA在宫颈癌的组织分化程度中,低分化组的表达高于高、中分化组(P<0.01),ⅡB～Ⅲ期显著高于I～ⅡA期(P<0.05);Survivin mRNA在淋巴结转移组中高于无淋巴结转移组(P<0.01);Survivin mRNA及Bcl-2与组织类型及肿块类型无关(P>0.05);HPV 16/18感染与宫颈癌组织类型、组织分化程度、临床分期、肿块类型均无关(P>0.05).(③Survivin与Bcl-2及HPV 16/18在宫颈癌中的表达均呈正相关.结论:Survivin、Bcl-2及HPV 16/18在宫颈癌中有异常表达.三者可能与宫颈癌的发生发展有密切关系.     

HPV E6/E7 mRNA在细胞学正常或轻度异常的低级别宫颈病变中的预测价值

目的:评估HPV E6/E7 mRNA检测对细胞学正常或轻度异常的低级别宫颈病变(CINⅠ)的预测价值。方法:选取2013年1月至2015年1月在衢州市人民医院妇科行初次阴道镜下活检且经组织病理学确诊为CINⅠ的81例患者进行随访。分析HPV E6/E7 mRNA与CINⅠ自然转归的定性及定量关系。结果:81例患者经2年随访,其中57例(70.4%)消退,8例(9.9%)持续,16例(19.8%)进展。在随访的6个月中,HPV E6/E7 mRNA阳性组与阴性组的CINⅠ总进展率比较,差异无统计学意义(P0.05);而在随访的12、18、24个月中,HPV E6/E7 mRNA阳性组的总进展率明显高于HPV E6/E7 mRNA阴性组(P0.05),且HPV E6/E7mRNA表达量越高,CINⅠ进展的可能性越大(r=0.678,P=0.000)。结论:对于细胞学正常或轻度异常的CINⅠ患者,HPV E6/E7 mRNA阳性,特别是高表达量的患者更易进展。     

HPV prevalence, E6 sequence variation and physical state of HPV16 isolates from patients with cervical cancer in Sichuan, China

OBJECTIVES: Infection with high-risk human papillomavirus (hr-HPV) is an important factor associated with cervical cancer. The genetic mutation of HPV16 E6 and integration of HPV16 DNA in the cervical carcinoma tissues are considered important genetic changes in cervical lesion progression. But the studies of hr-HPV epidemiology are relatively less in the area of Sichuan, China. Therefore, we investigated the prevalence of 9 high-risk subtypes and analyzed the genetic mutation characteristic of HPV16 E6 and physical state of HPV16 DNA. METHODS: The fragments of L1 and E6 genes were amplified by PCR or nested PCR and then directly sequenced. Further, the multiplex PCR for HPV16 E2 and E6 genes was performed for detection of integration. RESULTS: HPV16, 58 and 18 were prominent, accounting for 78.6%, 20.0% and 9.7%, respectively in 145 isolates. E6 variants revealed that the European (EP) prototype and East Asia (EA) strain were 26 (23.0%) and 34 (30.1%), respectively. Furthermore, there were 14 base substitutions in E6 regions of the study group, of which 12 resulted in amino acid changes and the rest was silent mutation. Significantly, the 240G substitution exactly located the P53 degradation site. Overall, 8 of 114 (7.0%) isolates only contained integrated HPV16 DNA, 43 (37.7%) only contained episomal DNA and 63 (55.3%) contained both integrated and episomal DNA. The proportion of disruption of an intact E2 gene in the patients with cervical cancer is much lower than that in the previous studies. CONCLUSIONS: HPV16, 58 and 18 were mainly prevailing subtypes in patients with cervical cancer from Sichuan areas, China and EP/EA strains were predominant in these areas. Some mutations of E6 gene, which lead to the amino acid changes, may be more potentially carcinogenic and the proportion of disruption of an intact E2 gene is much lower.     

The level of antibody against E6 HPV 16 oncoprotein in blood sera of women with chronic HPV 16 infection and cervical cancer

The aim of this study was to estimate of the role of chronic HPV 16 infection and the presence of anti E6 HPV 16 in the initiation of the cancerogenesis process of cervical cancer. MATERIAL AND METHODS: The study included two groups of patients. The first group comprised 323 women observed for three consecutive years (1998-2000), in whom the presence of HPV 16 viruses was estimated by PCR, and the level of anti E6 HPV 16 antibodies was estimated in the plasma with ELISA. A similar test was performed in a group of 46 patients with cervical intraepithelial neoplasia (CIN), 91 patients with invasive cervical cancer and 22 women after hysterectomy and RTG-therapy. RESULTS: In 32 patients, chronic HPV 16 infection showed a steady rise in the mean absorbance level of anti E6 HPV 16 antibodies from 0.04 in 1998 to 0.06 in 2000, while in HPV-negative women the mean absorbance value was 0.03-0.04. Mean absorbance value in patients with CIN III and invasive cancer rose with advancing stage of the cancer process and lowered after completion of oncological treatment. The values were 0.14, 0.33 and 0.13, respectively. CONCLUSION: The persistence of chronic HPV 16 infection and accompanying steady rise in absorbance index caused by an increase in the level of antiviral antibodies are a clear warning signal preceding in time the histological process of cancerogenesis.     

干扰素α-2b对宫颈癌细胞HPV16 E6E7基因抑制作用的研究

目的研究干扰素α-2b对宫颈癌SiHa细胞生长的调节作用，从细胞生物学及分子生物学水平探讨干扰素α-2b对宫颈癌细胞SiHa的作用机制。应用RT-PCR半定量检测细胞内HPV16 E6E7 mRNA表达，观察干扰素α-2b对宫颈癌SiHa细胞中HPV16 E6E7 mRNA表达的影响。方法以不同浓度的人重组干扰素α-2b含药培养液作用于感染HPV16的人宫颈癌细胞系——SiHa细胞，并设立无药对照，通过MTT及流式细胞分析技术检测该药对细胞生长及增殖的影响；进行细胞凋亡检测并用RT—PCR法半定量检测对HPV16 E6E7基因表达的影响。结果经含有干扰素α-2b的培养液作用后，细胞数量减少，1000IU／ml的干扰素α-2b对细胞抑制作用最强；细胞周期各时相中，S期细胞所占比例明显减少；均可诱导细胞凋亡；均使细胞中HPV16 E6E7mRNA表达明显减少。结论干扰素α-2b不仅可直接抑制宫颈癌细胞的生长，并可能通过抑制HPV16 E6E7基因表达的分子机制，达到抑制肿瘤目的。     

HPV16 E2基因各区域缺失与宫颈病变相关性的研究

目的:检测湖北地区HPV16阳性宫颈标本E2基因碳端(C)、铰链区(H)、氮端(N)的缺失状态,探讨其与CIN及宫颈癌的关系。方法:将122例宫颈标本按病变程度分为宫颈癌组、CINⅡ~Ⅲ组、对照组。应用多重聚合酶链反应(PCR)将各组HPV16感染标本E2基因的C、H、N分别与E6基因同时扩增,检测E2基因各区域的缺失状态,并应用Scion Image4.0软件半定量分析E2、E6基因条带灰度值,判断HPV DNA的整合状态。结果:宫颈癌组E2基因C、H、N缺失率分别是22.5%,50%,77.5%;CIN组为30.77%,69.23%,92.31%;对照组为9.09%,27.27%,27.27%。E2基因C、H缺失率在3组的任两组间比较无统计学差异(P0.05),而E2基因N端缺失率在宫颈癌组与对照组之间及CIN组与对照组之间差异有统计学意义(P均0.01)。结论:HPV16病毒E2基因N端缺失状态与CIN及宫颈癌有内在关系。在检测HPV感染同时检测E2基因N端缺失状态,对间接判断预后及指导后续治疗有重要意义。     

HPV16-specific cytotoxic T lymphocyte responses are detected in all HPV16-positive cervical cancer patients

OBJECTIVES: The specific CTL response against human papillomavirus (HPV) antigens in women with cervical cancer has been poorly studied. Immunological monitoring of this response is central for understanding the principles that underlie successful immunotherapeutic strategies. The aim of the study was to investigate the HPV16 E6/E7-specific CTL immune response in a group of untreated HPV16-positive cervical cancer patients. METHODS: Peripheral blood mononuclear cells from 21 untreated cervical cancer patients and 4 healthy controls were isolated prior to any therapy. Autologous monocyte-derived dendritic cells (MDDCs) were transiently transfected with HPV16 E6 or E7 expression vectors and used for one round of in vitro restimulation and as target cells in chromium release assays with restimulated peripheral blood lymphocytes. RESULTS: Transfected monocyte-derived dendritic cells were differentiated to exhibit a fully mature phenotype. HPV16 E6 and E7 transgenes were expressed and translated as measured by RT-PCR and intracellular flow cytometry, respectively. All HPV16-associated cervical cancer patients showed evidence of specific CTLs. Lytic activity for HPV16 E6 (11/12) and/or E7 (8/9) was above 30% at the 100:1 effector to target ratio. None of the HPV16-negative cervical cancer patients or healthy controls were above 15% of lysis. CONCLUSIONS: These data suggest that HPV-specific cytolytic immune responses can be detected in all untreated cervical cancer patients. Our approach, using dendritic cells for restimulation and as target cells, may enhance immunomonitoring of cervical cancer patients.     

Enhancing immunogenicity of HPV16 E7 DNA vaccine by conjugating codon-optimized GM-CSF to HPV16 E7 DNA

ObjectiveTo generate immunity against human papillomavirus (HPV), the use of a recombinant DNA vaccine to carry an appropriate target gene is a promising and cost-effective approach. Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a potent immunomodulatory cytokine that enhances the efficacy of vaccines by promoting the development and prolongation of humoral and cellular immunity. In this study, we linked codon-optimized GM-CSF (cGM-CSF) to the HPV16 E7 sequence as fused protein and evaluated the immunogenic potential of this DNA vaccine.Materials and methodsWe have demonstrated that cGM-CSF enhanced immunity against tumor challenges by generating and promoting the proliferation of HPV16 E7-specific CD8+ T cells, which secrete IFN-γ in the murine model. In this study, we aimed to evaluate the immunogenic potential of DNA vaccine that constructed by linking codon-optimized GM-CSF to HPV16 E7 sequence in the animal model. We study the half-life of RNA decay and cellular location of HPV16 E7 by Q-PCR and Western blot. We also assess immune response in the animal model by flow cytometry and ELISA.ResultsThe cGM–CSF–E7 sequence increased and extended the expression of E7 mRNA, in comparison with the E7 sequence alone. Mice vaccinated with the cGM–CSF–E7 DNA vaccine exhibited a slower rate of tumor growth than those vaccinated with the unconjugated E7 DNA vaccine. We also found that the CD4 and CD8+ T cells from these mice showed strong secretion of IFN-γ.ConclusionThrough in vivo antibody depletion experiments, we demonstrated that both CD4+ and CD8+ T cells play an important role in the suppression of tumor growth.     

E2 sequence variations of HPV 16 among patients with cervical neoplasia seen in the Indian subcontinent

OBJECTIVES: Specific nucleotide variations in the E2 DNA sequence were looked for in samples with an intact human papillomavirus (HPV) 16 episomal E2 DNA. METHODS: Ninety-two women, 76 with invasive cervical carcinoma and 16 with cervical intraepithelial neoplasia (CIN) were recruited. HPV DNA typing was performed by polymerase chain reaction (PCR) based restriction fragment length polymorphism (RFLP). Intact episomal E2 DNA of HPV 16 was detected by PCR. Important nucleotide variations in samples with amplifiable E2 DNA were detected by RFLP. Nucleotide sequencing was performed on representative samples to confirm RFLP findings. RESULTS: A total of 89 (96.7%) women were positive for HPV DNA. Of these, 56 (63%) were positive for HPV 16, and of these, 38 (68%) were positive for intact episomal HPV 16 E2 DNA while 18 (32%) were negative. Samples with intact episomal HPV 16 E2 DNA sequences were grouped into four different digestion profiles I to IV based on RFLP patterns. Digestion patterns revealed absence of any sequence variations in samples with digestion profile I and presence of a 2983 A-G variation in those with profile II. Samples with digestion profiles III and IV revealed three variations in the hinge region (3516 C-A, 3538 A-C, 3566 T-G) and two in the DNA binding domain (3684 C-A, 3694 T-A) of the E2 sequence. Sequencing performed on representative samples confirmed RFLP findings. CONCLUSIONS: PCR-RFLP helped in the identification of important HPV 16 E2 sequence variations, circumventing the need for sequencing. The presence of the nucleotide variations in positions that could alter the biological and immunological functions of the E2 protein combined with its increased occurrence in this study bring out the importance of these variations.