Detection of adeno-associated virus DNA in female genital samples by PCR-ELISA

Molecular Detection of Adeno-Associated Virus DNA in Cases of Spontaneous and Therapeutic Abortion

BACKGROUND

Adeno-associated viruses (AAVs) have been found in human blood cells, cervical biopsies, and epithelial cell brushings, endometrium, and abortion material, which suggest their possible roles in the induction of miscarriage.

OBJECTIVE

In this case control study, the presence of AAV DNA in placental tissue of spontaneous and therapeutic abortions was compared.

METHOD

Placenta samples were evaluated for AAV DNA by hemi-nested PCR in miscarriages occurring in the first 24 weeks of pregnancy from therapeutic and spontaneous abortions.

RESULTS

Eighty-one therapeutic abortions (control group) and 83 spontaneous abortions (case group) were evaluated. Sixty-two (38.2%) of 164 abortions were AAV positive, including 35 (21.6%) spontaneous abortions and 27 (16.6%) therapeutic abortions.

CONCLUSION

There was no statistically significant difference between the presence of the AAV genome in spontaneous and therapeutic abortions. This observation was consistent with other studies in this area.

Harnessing the Prokaryotic Adaptive Immune System as a Eukaryotic Antiviral Defense

Clustered, regularly interspaced, short palindromic repeats - CRISPR-associated (CRISPR-Cas) systems - are sequence-specific RNA-directed endonuclease complexes that bind and cleave nucleic acids. These systems evolved within prokaryotes as adaptive immune defenses to target and degrade nucleic acids derived from bacteriophages and other foreign genetic elements. The antiviral function of these systems has now been exploited to combat eukaryotic viruses throughout the viral life cycle. Here we discuss current advances in CRISPR-Cas9 technology as a eukaryotic antiviral defense.

Molecular detection of adeno-associated virus in cases of spontaneous and intentional human abortion

Pregnancy failure is a common event and often of unknown cause. Some viruses are thought to cause abortions including the adeno-associated viruses (AAV), viruses which are regarded as being without any definitive association to any human disease. This study investigated AAV infection in 81 human abortions, both spontaneous and intentional that occurred up to the 23rd week of gestation. Nucleic acid of AAV-2, 3, and 5 types from 118 decidual and chorionic tissues, collected from the patients in this study, was amplified by nested-PCR. In situ hybridization (ISH) was developed with a digoxigenin-labeled AAV probe in paraffin embedded tissues from the AAV positive cases. AAV was observed in 28.4% (23/81) of the cases, of which, 78.3% (18/23) were in the decidua and 21.7% (5/23) in the extravillous trophoblast, the chorionic plate, or chorionic villi fragments. AAV-2, the only type detected, occurred in 32.3% (22/68) and in 7.7% (1/13) of the spontaneous and intentional abortions, respectively. ISH revealed AAV in the decidua, chorionic tissue or chorionic plate and extravillous trophoblast. The detection of only AAV-2 type indicates that it is the most frequent in the population studied and/or shows tissue tropism. The presence of AAV in decidual or trophoblastic cells in cases of abortion, as observed by ISH, implies that the virus could jeopardize the pregnancy. The significant predominance in spontaneous cases suggests possibly a causal association between AAV and abortion.

Qualitative PCR-ELISA protocol for the detection and typing of viral genomes

PCR is an established technique providing rapid and highly productive amplification of specific DNA sequences. The demand for equally rapid, sensitive and objective methods to achieve detection of PCR products has led to the coupling of PCR with ELISA. PCR-ELISA involves direct incorporation of labeled nucleotides in amplicons during PCR-amplification, their hybridization to specific probes and hybrid capture-immunoassay in microtiter wells. PCR-ELISA is performed in 1 d and is very flexible, with the ability to process simultaneously up to 96 or 384 samples. This technique is potentially automatable and does not require expensive equipment, and thus can be fundamental in laboratories without access to a real-time PCR thermocycler. PCR-ELISA has mainly been used to detect infectious agents, including viruses, bacteria, protozoa and fungi. A PCR-ELISA protocol for the qualitative detection of papillomavirus genomes and simultaneous typing of different genotypes are detailed here as an example of the technique.

Detection of adeno-associated virus type 2 genome in cervical carcinoma

Adeno-associated virus (AAV) can impair the replication of other viruses. Adeno-associated virus seroprevalences have been reported to be lower among women with cervical cancer. In-vitro, AAV can interfere with the production of human papillomavirus virions. Adeno-associated virus-2 DNA has also been detected in cervical cancer tissue, although not consistently. To evaluate the role of AAV infection in relation to invasive cervical cancer, we performed a nested case–control study within a retrospectively followed population-based cohort. A total of 104 women who developed invasive cervical cancer on average 5.6 years of follow-up (range: 0.5 months–26.2 years) and 104 matched control-women who did not develop cervical cancer during the same follow-up time were tested for AAV and human papillomavirus by polymerase chain reaction. At baseline, two (2%) case-women and three (3%) control-women were positive for AAV-2 DNA. At the time of cancer diagnosis, 12 (12%) case-women and 3 (3%) matched control-women were positive for AAV-2 DNA. Persisting AAV infection was not evident. In conclusion, AAV-2 DNA was present in a low proportion of cervical cancers and we found no evidence that the presence of AAV in cervical smears of healthy women would be associated with reduced risk of cervical cancer.

Adeno-associated virus type 2 increases proteosome-dependent degradation of p21WAF1 in a human papillomavirus type 31b-positive cervical carcinoma line

Adeno-associated virus type 2 (AAV2) seropositivity is negatively correlated with the development of human papillomavirus (HPV)-associated cervical cancer. We have begun analysis of the molecular mechanisms underlying AAV2-mediated onco-suppression through cell cycle regulation in HPV-infected keratinocytes isolated from a low-grade cervical lesion. AAV2 superinfection of HPV type 31b (HPV31b)-positive cells at early times postinfection resulted in degradation of the cyclin-dependent kinase (CDK) inhibitor p21(WAF1) protein in a proteosome-dependent manner. Downstream consequences of lowering p21(WAF1) levels included a proportional loss of cyclin E/CDK2 complexes bound to p21(WAF1). The loss of stable p21(WAF1)/cyclin E/CDK2 complexes coincided with an increase in CDK2-associated kinase activity and cyclin E levels. Both events have the potential to enhance the G(1)/S transition point mediated by active cyclin E/CDK2 complexes. Concurrently, cyclin A and E2F levels were decreased, conditions reminiscent of delayed entrance into the S phase of the cell cycle. On the other hand, infection of primary human foreskin keratinocytes with AAV2 resulted in upregulation of p21(WAF1) protein levels, reminiscent of a block in G(1) phase progression. We propose that by down regulating p21(WAF1), AAV2 initiates cell cycle activities leading to enhanced G(1)/S phase-like conditions which may be favorable for AAV2-specific functions and may lead to downstream interference with HPV-associated cervical cancer progression.

Correlation of human papillomavirus and adeno-associated virus 2 infection in cytology with Korean women

The purpose of our prospective study was to investigate the prevalence of adeno-associated virus (AAV) and human papillomavirus (HPV) 16 and/or HPV 18 infection in Korean women with normal cervical smears and those with HPV-associated cervical intraepithelial neoplasia (CIN) and cancer in cytobrush samples, and to evaluate the correlation between AAV 2 and HPV 16 and/or HPV 18 infection. AAV 2 was detected in CIN I (9.7%), CIN II (20%), CIN III (22.8%), and cancer (10%). HPV 16 was detected in CIN I (42%), CIN II (55%), CIN III (54.3%), and cancer (70%). HPV 18 was detected in CIN I (51.6%), CIN II (50%), CIN III (62.8%), and cancer (43.3%). HPV 16 or HPV 18 was detected in CIN I (18.3%), CIN II (80%), CIN III (71.4%), and cancer (80%). In normal and HPV-infected group, AAV 2 DNA was detected in 16.3% and 4.4% of samples, respectively. HPV 16 was detected in 10.2% of normal patients and in 44.4% of HPV-infected patients, and HPV 18 was detected in 12.2% of normal patients and in 40% of HPV-infected patients. HPV 16 or HPV 18 was detected in 18.3% of normal patients and in 57.7% of HPV infection. The correlation between AAV 2 and HPV 16 was statistically significant in normal and CIN I/II group only, and AAV 2 and HPV 16 and/or HPV 18 showed no correlation. Therefore, the correlation between AAV and HPV were not statistically significant. These data support the previous reports that AAV might not be associated with cervical tumorigenesis.

A DNA recombination-based approach to eliminate papillomavirus infection

At present, no treatments exist that effectively target and eliminate papillomaviruses (PVs) from infected cells or prevent its replication. We are employing a strategy to prevent virus replication in PV-infected cells through the conditional expression of the herpes simplex virus type 1 thymidine kinase (TK) gene. Expression of TK in this system is expected to be triggered by a homologous recombination event between the endogenous PV genome and a nonexpressing TK gene cassette. Recombination between these two DNAs is expected to change the nonexpressing cassette into a form that expresses TK. Various constructs were generated to express the TK in the above manner. Transfection of cell lines with a TK nonexpressing plasmid did not result in TK production due to alternative splicing and polyadenylation site selection. However, cotransfection of cell lines with PV plasmids along with the above TK construct containing short segments of PV sequences resulted in a recombination event that led to TK expression as shown by Northern and Western blot analyses. We also developed a TK expression cassette utilizing an adeno-associated virus (AAV) vector. Delivery of the cassette by AAV to PV-infected cells resulted in TK expression, and ganciclovir treatment resulted in efficient killing of these cells.

Possible role of bacterial and viral infections in miscarriages

OBJECTIVE

To determine the role of infections in miscarriages. Chorionic villi from aborted material were subjected to cytogenetic evaluation and analyzed for the presence of Chlamydia trachomatis, Ureaplasma urealyticum, Mycoplasma hominis, human cytomegalovirus (HCMV), adeno-associated virus (AAV), and human papillomaviruses (HPV).

DESIGN

Retrospective study.

SETTING

University hospital and academic research institution.

MAIN OUTCOME MEASURE(S)

Karyotyping and detection of bacterial and viral DNA by means of polymerase chain reaction (PCR) in placenta specimens.

RESULT(S)

In 54 (50%) of 108 samples the karyotype was normal, in 38 (35%) samples it was abnormal, and in 16 (15%) samples karyotype was undetermined. No U. urealyticum, M. hominis, HCMV, or AAV-2 DNA was detected, while C. trachomatis DNA was detected in one (1%) and HPV DNA in eight (7%) samples. No significant correlation of HPV-positive findings with karyotype status was established.

CONCLUSION(S)

Our findings do not support a role of C. trachomatis, U. urealyticum, M. hominis, HCMV, or AAV infections in miscarriages during the first trimester of pregnancy. However, further investigation should be made to determine a possible involvement of HPVs in the development of genetic abnormalities of the fetus and in miscarriages.

Evaluation of adenoassociated virus 2 and human papilloma virus 16 and 18 infection in cervical cancer biopsies

OBJECTIVE

Protective roles of adenoassociated virus (AAV) 2 in cervical tumorigenesis are controversial. In an effort to clarify this issue, we tested prevalence of AAV 2 and human papillomavirus (HPV) infection in cervical lesions and adjacent normal tissues.

METHODS

Tissues of cervical intraepithelial neoplasm (CIN) I (20 patients), CIN II (24 patients), CIN III (25 patients), and invasive cancer (23 patients) were investigated by microdissection and PCR using HPV-16-, HVP-18-, and AAV-2-specific primers.

RESULTS

AAV 2 was detected in 11 out of 20 CIN I (55%), 21 out of 24 CIN II (84.5%), 13 out of 25 CIN III (52%), and 12 out of 23 invasive cancer cases (52.2%). However, HPV 16 was detected in none out of 20 CIN I, 2 out of 24 CIN II (8.3%), 6 out of 25 CIN III (24%), and 6 out of 23 invasive cancer cases (26.1%). HPV 18 was detected in 1 case in CIN II (4.2%) and 2 cases in CIN III (8%). In 92 perilesional normal tissues, AAV 2 was detected in 53 cases (57.6%), displaying 25% of CIN I, 83.3% of CIN II, 52% of CIN III, and 65.2% of invasive cancer.

CONCLUSION

The differences in AAV 2 prevalence are not significant between CIN and normal tissues. However, differences in HPV 16 are significant in CIN III and invasive cancer, as compared to CIN I, CIN II, and normal, suggesting no significant correlation between AAV 2 and cervical cancer. Thus, these results support the notion that AAV 2 is not associated with cervical tumorigenesis.

Temporal acceleration of the human papillomavirus life cycle by adeno-associated virus (AAV) type 2 superinfection in natural host tissue

Epidemiologically, certain human papillomaviruses are positively associated with cervical cancer, while adeno-associated viruses (AAV-2) are negatively associated with this same cancer. Both HPV and AAV productively replicate in differentiating keratinocytes of the skin and interact with each other. However, AAV has a relatively fast life cycle, generating infectious progeny by the third to fourth day of an organotypic epithelial raft culture. In contrast, HPV is slow, generating infectious progeny only after 10-12 days. As earlier studies indicated that these two skin-tropic virus types significantly affect each other's life cycle, we investigated if the temporal kinetics of the slow HPV life cycle was affected by the fast AAV in raft cultures. Here it is shown that the presence of AAV-2 at a variety of multiplicities of infection (m.o.i.) resulted in early onset HPV-31b DNA replication. Using plasmids which each expressed only one of the four rep proteins, an enhancement affect was seen for all four rep proteins of AAV, with Rep40 having the highest activity. Furthermore, AAV (m.o.i. of 5) also resulted in a temporally accelerated production of HPV infectious units, seen as early as Day 4, with high levels of viral progeny being produced by Day 6.5. Like earlier studies at Day 12, histological differences were seen at Day 6.5 between AAV-infected and mock-infected HPV/rafts. These data suggest that under specific conditions the AAV rep trans-factors can positively regulate HPV gene expression in addition to the usual negative regulation that has been consistently observed by the rep proteins. These data also suggest that AAV has a significant effect upon the temporal kinetics of the HPV life cycle in natural host tissue. However, it is unclear if or how this AAV-induced fast HPV life cycle mechanistically correlates with lower rates of HPV-associated cervical disease.

Adeno-associated virus DNA in human gestational trophoblastic disease

Previous studies had shown a correlation between infection with the human adeno-associated virus (AAV) and spontaneous abortion in early pregnancy. Furthermore, AAV DNA had been detected in cells of the human trophoblast lines, Jeg-3, JAr, and BeWo, in cells of the human amnion line, FL, and in trophoblasts from amnion fluids. Infectious AAV virions could be isolated from amnion fluids. To further analyse AAV infection during pregnancy, we tested material from Gestational Trophoblastic Disease for the presence of AAV DNA. With 63 tissue samples from patients from Brazil, including 49 hydatiform moles and 14 choriocarcinomas, nested PCR was performed to detect the presence of AAV DNA. In addition, 15 samples from spontaneous abortions were analysed. AAV DNA was found in 43 samples (28/49 hydatiform moles, 4/14 choriocarcinomas, 11/15 miscarriage material). These findings confirm AAV infection of embryo-derived tissue in humans and further suggest a role of AAV in miscarriage and trophoblastic disease.

Adenoassociated virus type 2-induced inhibition of the human papillomavirus type 18 promoter in transgenic mice

The epithelium of the cervix uteri has been reported to be frequently coinfected with both human papillomaviruses (HPV) and helper virus-dependent adenoassociated viruses (AAV). Seroepidemiological data suggest that AAV infection could inhibit cervical cancer that is caused by specific ("high-risk") types of papillomaviruses. In vitro, infection with AAV type 2 (AAV-2) or transfection of AAV-2 early (rep) genes has been shown to inhibit transformation by papillomaviruses. To analyze the effects of AAV on HPV in vivo, we studied the influence of AAV-2 infection on the promoter activity of high-risk HPV type 18 (HPV-18) in mice, transgenic for sequences of the upstream regulatory region (URR) of HPV-18 controlling transcription of the reporter gene, lacZ. Transgenic animals (or tongue cells thereof, explanted and grown in culture) were treated with dexamethasone to induce the HPV-18 promoter. Simultaneously they were (i) infected with AAV, (ii) inoculated with AAV virus-like particles (VLPs; empty capsids), or (iii) mock infected. Inoculation with AAV-2 or VLPs inhibited activation of the HPV-18 promoter. In vitro, in baby hamster kidney cells transfected with the HPV-18-lacZ construct, tissue extracts from AAV-infected animals suppressed the HPV-18 URR to a similar extent as AAV infection did. Down-regulation of the HPV-18 promoter was less efficient with extracts from animals inoculated with VLPs and was not observed with extracts from uninfected or dexamethasone-treated animals. This indicates that AAV induces cellular factor(s) in vivo capable of mediating down-regulation of the HPV-18 promoter also in cells in vitro. In contrast, promoters of the low-risk HPV types (HPV-6, HPV-11) were not influenced by AAV infection as opposed to promoters of the high-risk types (HPV-18 and HPV-16).