Aims: We aimed at identifying the high-risk HPV genotypes associated with high-grade dysplastic cervical lesions in Burkina Faso. The available vaccines to Burkina Faso only protect against two high risk HPV genotypes: HPV 16 and 18. Are the genotypes identified in the high-grade precan-cerous lesions in this survey covered by the available vaccines? Methods: The detection and genotyping of high-risk HPV have been conducted based on 118 formalin-fixed and paraffin-embedded archived tissues using the “HPV Genotypes 14 Real-TM Quant” (Sacace biotechnologies ®, Italy) kit allowing for the detection of fourteen high-risk HPV genotypes: HPV 16, 31, 18, 39, 45, 59, 33, 35, 56, 68, 51, 52, 58 and 66. Results: The prevalence of high-risk HPV infections was 48.8% based on the appropriate PCR results (21/43). The most common HPV genotypes were HPV 39 (21.7%), HPV 35 (13.0%) and HPV 45 (13.0%). Two cases of multiple infections between HPV 39 - 45 and HPV 39 - 59 have been observed. HPV 16 was not detected in this study. Conclusions: We noted a high prevalence rate for HPV 39, HPV 35 and HPV 45, which are not covered by the commercial vaccines. We also found that the prevalence of HPV 18 was very low in this study and HPV 16 was not detected.
Human Papillomavirus (HPV) is involved in cervical cancer, cancers of the anogenital and oropharyngeal areas, and benign lesions such as condylomata acuminata and warts [
This was a cross-sectional study with retrospective data collection in which all cases diagnosed between February 2009 and May 2015 as high-grade intraepithelial lesions have been selected. There were a total of 118 tissues with cases of high-grade precancerous lesions. These tissues were archived in paraffin in the Department of Anatomy and Cytopathology of the Yalgado Ouedraogo University Hospital (CHU-YO). Cuts have been made on paraffin blocks using a microtome. Samples of five thin sheets with a thickness being ≤ 20 µm were made on each cassette and stored in Eppendorf sterile and encoded tubes and transported to the Pietro Annigoni Biomolecular Research Center/Laboratory of Molecular Biology and Molecular Genetics (CERBA/LABIOGENE) for molecular testing.
The HPV DNA was extracted using the commercial kit known as FFPE DNA Purification Product # 47400 (NORGEN BIOTEK CORPORATION, Canada). Before conducting the actual extraction, the samples underwent xylene-dewaxing.
The extraction was performed following the protocol provided by the manufacturer using micro-columns equipped with collecting tubes. The DNA thus extracted was stored at −20˚C until amplification.
Amplification was done using the kit named HPV Genotypes 14 Real-TM Quant (Sacace Biotechnologies®, Italy) which is a real-time multiplex PCR test for the detection of 14 HR-HPV genotypes (HPV-16; 18; 31; 33; 35; 39; 45; 51; 52; 56; 58; 59; 66 and 68). Each sample underwent multiplexed amplification in 4 tubes and each tube contained primers of the E6 and E7 target regions of three or four types of HR-HPV and human beta-globin gene as internal control (IC). For each sample, we prepared the following for the 4 tubes respectively: PCR-mix- 1 16, 18, 31, IC; PCR-mix-1 39, 45, 59, IC; PCR-mix-1 33, 35, 56, 68; PCR-mix-1 51, 52, 58, 66. The pre-PCR steps included the following: preparing the Mix solution (PCR-buffer-FRT + Hot Start DNA Polymerase) and the Reaction Mix solution (Mix solution + each PCR-mix-1). For each sample, we introduced 15 μL of the Reaction Mix solution in the 4 tubes and we added 10 μL of the DNA extract. It was the same for the negative control and standards. The total reaction volume was 25 μL. The amplification program was: 1 cycle of 95˚C for 15 min; 5 cycles of 95˚C for 5 seconds followed by 60˚C for 20 seconds and 72˚C for 15 seconds; and finally 40 cycles of 95˚C for 5 seconds followed by 60˚C for 30 seconds and 72˚C for 15 seconds. The PCR is valid if the standards show signal for all the FAM, JOE, ROX, and Cy5 fluorochromes and if the negative control has no signal. The results were interpreted using the Microsoft Excel program named “HPV Genotypes 14 Real- TM.xls” (Sacace Biotechnologies®, Italy) provided by the manufacturer.
The statistical analysis was conducted using SPSS Statistics 17.0. The Chi-square test was used for comparisons using the Epi Info 6.04d software. The difference was significant for p < 0.05.
This study was approved by the Ethics Committee for Health Research (CERS) N2014-8-099 of August 6, 2014. The committee authorizes the use of this archives samples. We complied with the confidentiality and anonymity condition with respect to information obtained from the various registers and the patient charts are kept strictly confidential.
This study involved 118 tissues diagnosed as high-grade precancerous lesions according to the minutes of the histological result. The age of patients ranged from 22 to 74 years with a mean of 41.5 years and a standard deviation of 9.8 years.
Following the histological examination, the various samples have been classified according to the Bethesda classification as grade 2 or 3 Cervical Intraepithelial Neoplasia (CIN) or CIN 2 or CIN 3. Of the samples, 46.6% presented cervicitis (acute, subacute or chronic). Samples whose β-globin internal control gene could not be amplified were classified negative β-globin. In our study, 63.6% or 75/118 samples were negative β-globin; they were therefore declared inappropriate. The histological results and the PCR results are shown in
Number | % | 95% CI | p value | ||
---|---|---|---|---|---|
Histological diagnostic | |||||
CIN 2 | 32 | 27.1 | 19.3 - 36.1 | p < 0.001 | |
CIN 3 | 86 | 72.9 | 63.9 - 80.7 | ||
Cervicitis | 55 | 46.6 | 37.4 - 56.0 | ||
Presence of β-globine | |||||
β-globine+ | 43 | 36.4 | 27.8 - 45.8 | p < 0.001 | |
β-globine− | 75 | 63.6 | 54.2 - 72.2 | ||
Status HPV | |||||
HPV+ | 21 | 17.8 | 11.4 - 25.9 | p < 0.001 | |
HPV− | 22 | 18.6 | 12.1 - 26.9 | ||
Invalid | 75 | 63.6 | 54.2 - 72.2 | ||
Total | 118 | 100 |
There were 21 women who were positive to at least one HR-HPV genotype out of the 118 resulting in a proportion of 17.8%. However, taking into account the results of the PCR, out of the 43 adequate results, the prevalence of HR-HPV infections is 48.8%. We will only consider the adequate results.
The kit used helped to characterize 14 HR-HPV genotypes. These were HPV 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66 and 68. By combining the HR-HPV genotypes, considering the fact that some women were infected with more than one genotype, the total number of genotypes found was 23 and 11 HR-HPV types have been found out of the 14 sought.
The prevalence of HPV 39 infection was the highest with a frequency of 21.7%. HPV16 genotype was not detected in the study population. The prevalence of HPV 35 and HPV 45 genotypes was 13% each. Genotypes of HPV 33, 51, 52 and 56 also have the same prevalence rate of 8.7%. HPV 18, HPV 59 and HPV 68 genotypes accounted for 4.3% respectively.
The HR-HPV genotypes found in CIN 2 represent 37.5% of the 32 cases of CIN 2 diagnosed; while HR-HPV found in CIN 3 represent only 12.8% of the 86 cases of CIN 3 diagnosed.
The two cases of multiple infections are carried by women aged 31 and 40 years. They represented 9.5% against 90.5% for simple infections. These two associations were HPV 39; 45 and HPV 39; 59. The HPV 39 genotype which is the most represented genotype was present in 100% of multiple infection cases.
HPV 39 genotype was the only one that is found in almost all age groups. HPV 18 genotype was found in the age group of 30 - 39 years.
HR-HPV infection is widespread in all age groups. However, the age groups of 30 - 39 years and 40 - 49 years were the most representative. The age group of 20 - 29 years is the only age group that recorded any genotype.
Histological types | ||||||
---|---|---|---|---|---|---|
CIN 2 | CIN 3 | |||||
n = 32 | % | 95% CI | n = 86 | % | 95% CI | |
Genotypes HPV | ||||||
HPV 16 | 0 | 0 | 0.0 - 0.0 | 0 | 0 | 0.0 - 0.0 |
HPV 18 | 0 | 0 | 0.0 - 0.0 | 1 | 1.2 | 0.0 - 6.3 |
HPV 31 | 0 | 0 | 0.0 - 0.0 | 1 | 1.2 | 0.0 - 6.3 |
HPV 33 | 1 | 3.1 | 0.1 - 16.2 | 1 | 1.2 | 0.0 - 6.3 |
HPV 35 | 1 | 3.1 | 0.1 - 16.2 | 2 | 2.3 | 0.3 - 8.1 |
HPV 39 | 3 | 9.4 | 2.0 - 25.0 | 2 | 2.3 | 0.3 - 8.1 |
HPV 45 | 3 | 9.4 | 2.0 - 25.0 | 0 | 0 | 0.0 - 0.0 |
HPV 51 | 1 | 3.1 | 0.1 - 16.2 | 1 | 1.2 | 0.0 - 6.3 |
HPV 52 | 0 | 0 | 0.0 - 0.0 | 2 | 2.3 | 0.3 - 8.1 |
HPV 56 | 1 | 3.1 | 0.1 - 16.2 | 1 | 1.2 | 0.0 - 6.3 |
HPV 58 | 0 | 0 | 0.0 - 0.0 | 0 | 0 | 0.0 - 0.0 |
HPV 59 | 1 | 3.1 | 0.1 - 16.2 | 0 | 0 | 0.0 - 0.0 |
HPV 66 | 0 | 0 | 0.0 - 0.0 | 0 | 0 | 0.0 - 0.0 |
HPV 68 | 1 | 3.1 | 0.1 - 16.2 | 0 | 0 | 0.0 - 0.0 |
Total | 12 | 37.5 | 11 | 12.8 |
Histology and genotypes | Age group | Total | ||||||
---|---|---|---|---|---|---|---|---|
20 - 29 | 30 - 39 | 40 - 49 | 50 - 59 | ≥60 | Unknown | |||
CIN 2 | HPV 33 | 0 | 0 | 1 | 0 | 0 | 0 | 1 |
HPV 35 | 0 | 0 | 1 | 0 | 0 | 0 | 1 | |
HPV 39 | 0 | 1 | 1 | 0 | 1 | 0 | 3 | |
HPV 45 | 0 | 3 | 0 | 0 | 0 | 0 | 3 | |
HPV 51 | 0 | 1 | 0 | 0 | 0 | 0 | 1 | |
HPV 56 | 0 | 0 | 1 | 0 | 0 | 0 | 1 | |
HPV 59 | 0 | 0 | 1 | 0 | 0 | 0 | 1 | |
HPV 68 | 0 | 0 | 1 | 0 | 0 | 0 | 1 | |
Total | 0 | 5 | 6 | 0 | 1 | 0 | 12 | |
CIN 3 | HPV 18 | 0 | 1 | 0 | 0 | 0 | 0 | 1 |
HPV 31 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | |
HPV 33 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | |
HPV 35 | 0 | 0 | 2 | 0 | 0 | 0 | 2 | |
HPV 39 | 0 | 1 | 0 | 1 | 0 | 0 | 2 | |
HPV 51 | 0 | 1 | 0 | 0 | 0 | 0 | 1 | |
HPV 52 | 0 | 1 | 0 | 1 | 0 | 0 | 2 | |
HPV 56 | 0 | 0 | 1 | 0 | 0 | 0 | 1 | |
Total | 0 | 4 | 3 | 2 | 1 | 1 | 11 |
One limitation of our study is the relatively small sample size (118) and also the fact that the formalin-fixed tissues archived in the pathology anatomy laboratory are from different services hence the period of storage after fixation is varied. This situation probably caused some samples to be inadequate or could have affected the HPV detection rate. The use of formalin and the Bouin solution may have deteriorated the HPV DNA, in some samples. Despite these possible limitations, this study adds to available data on HPV prevalence and genotype distribution among women with cervical lesions in Ouagadougou and adds to the evidence that it is possible to use achieved tissue samples to detect and type for HPV. It also employed a rigorous hr-HPV genotyping method and assay which is commercially available.
HPV positive samples were 48.8%, based on valid results. The positivity rate is lower than most of the results according to numerous studies [
Other studies have shown results that differ from ours [
Our HPV positivity rate was 48.8% or 21 out of 43. In Pakistan, Siddiqa et al. found 94.8% (or 73/77) of HPV positive [
Among Danish women, a study found 290 valid results over 276 cervical samples of high-grade lesions including 100% HPV positivity against 48.8% of HPV positivity in our study (p < 0.001) [
In our study, the most frequent genotype was HPV 39 (21.7%). HPV 18 (4.3%) was less represented with only one case in the age group of 30 - 39 years. The notable absent was HPV 16 genotype yet found in many studies and recognized as one of the highest prevalence rates and being the subject of prophylactic vaccines currently available. In South Africa, McDonald et al. showed high proportion of cervical lesions (CIN2 and CIN3, respectively) due to HPV 16 (22.58% and 40.28%), HPV 35 (31.18% and 19.44%) and HPV 33 (12.90% and 12.50%) [
Among Cameroonian women with invasive cervical cancer, the three most common high-risk types were HPV 16 (88%), HPV 45 (32%) and HPV 18 (14.8%) [
We encountered two cases of multiple infections (double HPV) in 9.5% of the cases. Garcia-Espinosa et al. found 18.4% of multiple infections. [
We did not observe any correlation between the different associations of HPV genotypes, as the phenomenon is not well understood. We found no significant link between the histological lesions and the HPV carrier. In our study, the prevalence rate of precancerous lesions was significantly lower than that of most studies [
The size of our sample is not large enough to properly assess the relationship between the age and the HPV carrier. The higher age in our study could be the reason why we did not find some genotypes due to clearance; this could also explain the low HPV prevalence.
The results of our study show that the distribution of the HPV types can be determined by using pathological anatomy tissues such as paraffin blocks which allow the assessment of changes over time. But precautions shall be taken to avoid false negatives and inadequate samples. In addition, there is a need to optimize the methods of histology sample conservation in order to keep the DNA of these cells as intact as possible. Cervical cancer can be prevented by early diagnosis of precancerous lesions and through molecular characterization of the various genotypes circulating in each geographical area in order to better direct research on new multivalent vaccines. To do this, the establishment of an African mapping of high-risk HPV is required.
The authors are thankful to the Pietro ANNIGONI Association and the WAEMU Commission through the PACER-II program for their financial support.
Charlemagne Ouédraogo,Théodora Mahoukèdè Zohoncon,Esther M. A. Traoré,Souleymane Ouattara,Prosper Bado,Clarisse T. Ouedraogo,Florencia W. Djigma,Djénéba Ouermi,Dorcas Obiri-Yeboah,Olga Lompo,Simon A. Akpona,Jacques Simpore, (2016) Distribution of High-Risk Human Papillomavirus Genotypes in Precancerous Cervical Lesions in Ouagadougou, Burkina Faso. Open Journal of Obstetrics and Gynecology,06,196-204. doi: 10.4236/ojog.2016.64025