Chemistry: molecular biology and microbiology – Measuring or testing process involving enzymes or... – Involving virus or bacteriophage
Reexamination Certificate
2000-03-16
2002-11-19
Horlick, Kenneth R. (Department: 1637)
Chemistry: molecular biology and microbiology
Measuring or testing process involving enzymes or...
Involving virus or bacteriophage
C435S006120, C435S091100, C536S024320
Reexamination Certificate
active
06482588
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of detection and identification of Human Papillomavirus (HPV) infections in clinical samples.
BACKGROUND OF THE INVENTION
Cervical cancer is the second most common malignancy in women, following breast cancer. Carcinoma of the cervix is unique in that it is the first major solid tumor in which HPV DNA is found in virtually all cases and in precursor lesions worldwide.
Nowadays, 74 HPV genotypes have been characterized and are numbered in chronological order of isolation. HPV is epitheliotropic and infects only the skin (cutaneous types) or the mucosa of the respiratory and anogenital tract (mucosal types). Thirty-six of the 74 HPV types are known to infect the uterine cervix. Based on the induced benign, premalignant or malignant lesions, HPV is divided into low-risk (e.g., HPV types 6, 11, 42, 43 and 44) and high-risk types (e.g., types 16, 18, 31, 33 and 45), respectively. The high-risk types account for more than 80% of all invasive cervical cancers. Consequently, detection and identification of HPV types is very important. The high-risk types are more consistently found in high grade SIL (Squamous Intraepithelial Lesion) and carcinoma in-situ than low-risk types which are mainly found in low grade SIL. This epidemiological observation is supported by molecular findings. For instance, the E6 and E7 proteins from low-risk types 6 and 11 bind p53 and pRB too weakly to immortalize keratinocytes in vitro or to induce malignant transformation in vivo (Woodworth et al., 1990). The circular ds-DNA genome of low-risk HPV types remains episomal whereas the genome of high-risk HPV types is able to integrate into the human genome.
Screening for malignant and premalignant disorders of the cervix is usually performed according to the Papanicoloau (PAP) system. The cervical smears are examined by light microscopy and the specimens containing morphologically abnormal cells are classified into PAP I to V, at a scale of increasing severity of the lesion. This cytomorphological method is an indirect method and measures the possible outcome of an HPV infection. Therefore, HPV DNA detection and typing is of importance in secondary screening in order to select patients for monitoring (follow-up) and treatment. This means that cervical smears classified as PAP II (atypical squamous metaplasia) or higher classes should be analyzed for low-risk and high-risk HPV types. Follow-up studies have shown that only high-risk HPV types are involved in the progression from cytologically normal cervix cells to high grade SIL (Remminck et al., 1995). These results indicate that the presence of high-risk HPV types is a prognostic marker for development and detection of cervical cancer.
Detection of HPV Infections
Diagnosis of HPV by culture is not possible. Also diagnosis by detection of HPV anti-bodies appears to be hampered by insufficient sensitivity and specificity. Direct methods to diagnose an HPV infection are mainly based on detection of the viral DNA genome by different formats of DNA/DNA hybridization with or without prior amplification of HPV DNA. The polymerase chain reaction (PCR) is a method that is highly efficient for amplification of minute amounts of target DNA. Nowadays, mainly three different primer pairs are used for universal amplification of HPV DNA. Two of these primer pairs, MY11/MY09 and GP5/GP6, are directed to conserved regions among diffent HPV types in the L1 region (Manos et al., 1989; Van den Brule et al., 1990). The other primer pair, CPI/CPIIg, is directed to conserved regions in the El region (Tieben et al., 1993).
Typing of HPV Isolates
There are several methods to identify the various HPV types.
1. HPV DNA can be typed by PCR primers that recognize only one specific type. This method is known as type-specific PCR. Such methods have been described for HPV types 6, 11, 16, 18, 31 and 33 (Claas et al., 1989; Cornelissen et al., 1989; Falcinelli et al., 1992; Van den Brule et al., 1990; Young et al., 1989). The primers are aimed at the E5, L1, E6, L1, E2 and E1 regions of the HPV genome for types 6, 11, 16, 18, 31 and 33, respectively (Baay et al., 1996). The synthesized amplimer sizes vary from 217 bp to 514 bp.
2. Another method is general amplification of a genomic part from all HPV types followed by hybridization with two cocktails of type-specific probes differentiating between the oncogenic and non-oncogenic groups, respectively. A similar typing method has been described without prior amplification of HPV DNA. In the Hybrid capture assay (Hybrid Capture Sharp Assay; Digene, Silver Springs, Md.), each sample is tested for a group of “high-risk” HPV types (16, 18, 31, 33, 35, 45, 51, 52 and 56) and for another group of “low-risk” HPV types (6, 11, 42, 43 and 44) (Cox et al., 1995).
At present, classification of human papillomaviruses can be performed for instance by sequence analysis of a 450 bp PCR fragment synthesized by the primers MY11/MY09 in the L1 region (Chan et al., 1995) or by the primers CPI and CPIIg in the E1 region (Tieben et al., 1993). Phylogenetic analysis of these sequences allows classification of the different HPV types. By definition, if the sequence differences between two HPV isolates is higher than 10% they are classified as different types. Consequently, if the sequence differs more than 10% from any known HPV type it is classified as a novel HPV genotype. HPV isolates that differ between 2-10% are classified as different subtypes. Finally, if the sequence variation is below 2%, the 2 isolates are classified within the same subtype as different variants.
Aims of the Invention
It is an aim of the present invention to provide a rapid and reliable method for detection and/or identification of HPV, possibly present in a biological sample.
It is more particularly an aim of the present invention to provide a method for detection and/or identification of HPV comprising amplification of a polynucleic acid fragment of HPV and subsequent hybridization of this fragment to suitable probes.
It is also an aim of the present invention to provide a number of oligonucleotide primers and probes enabling said method of detection and/or amplification of HPV.
It is also an aim of the present invention to provide new HPV sequences.
It is furthermore an aim of the present invention to provide protocols according to which said amplification and hybridization steps can be performed. One format for the hybridization step is, for instance, the reverse hybridization format, and more particularly the LiPA technique.
It is also an aim of the present invention to compose diagnostic kits comprising said primers and probes, permitting the rapid and reliable detection and/or identification of HPV possibly present in a biological sample.
All the aims of the present invention are met by the following specific embodiments.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides a method for detection and/or identification of HPV, possibly present in a biological sample, comprising the following steps:
(i) amplification of a polynucleic acid fragment of HPV by use of:
a 5′-primer specifically hybridizing to the A region or B region of the genome of at least one HPV type, said A region and B region being indicated in
FIG. 1
, and
a 3′-primer specifically hybridizing to the C region of the genome of at least one HPV type, said C region being indicated in
FIG. 1
;
(ii) hybridizing the amplified fragments from step (i) with at least one probe capable of specific hybridization with the D region of at least one HPV type, said D region being indicated in FIG.
1
.
According to one preferred embodiment of the present invention, said probe mentioned in step (ii) is capable of specific hybridization with the D region of the genome of only one HPV type, and thus enables specific identification of this HPV type, when this type is present in a biological sample.
According to another preferred embodiment of the present invention, said probe mentioned in step (ii) is capable of specific hybridization with th
Kleter Berhnard
Quint Wim
TerSchegget Jan
Van Doorn Leen-Jan
Bierman, Muserlian and Lucas
Horlick Kenneth R.
Innogenetics S.A.
Strzelecka Teresa
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