Adeno-associated virus is associated with a lower risk of high-grade cervical neoplasia

A dual role for adeno-associated virus in human health

Adeno-associated virus (AAV) differs from most other viruses, as it requires the simultaneous presence of a helper virus for an active infection. Up to 80% of the human population is seropositive for AAV antibodies. AAV has been known to be a non-pathogenic virus and an inhibitor of carcinogenesis caused by coinfecting viruses. However, the recent reports associating AAV infection with hepatocellular carcinoma development and the mysterious cases of acute severe hepatitis in children have challenged the idea that AAV is a harmless virus. Herein, we explore the usefulness of AAV in gene therapy and the importance of AAV as a protector or perpetrator in human carcinogenesis, ultimately reflecting on the dual role of AAV in human health.

Adeno-associated virus infection and its impact in human health: an overview

Discovered as a contaminant of adenovirus stocks in the 1960s, adeno-associated virus (AAV) is a mono-stranded DNA virus that depends on helper factors to replicate. Even though AAV is endemic in the human population (35-80%), it is remarkable that many issues concerning the natural infection by this virus remain unanswered. In this study, we reflect on the main basic aspects of AAV biology and provide an overview of the studies exploring the impact of AAV infection on human health, focusing on three major research areas including, (i) cervical and (ii) liver cancer, and (iii) reproductive system disorders. Conflicting results have been obtained into the association of AAV infection with the occurrence of adverse reproductive outcomes, such as placental complications, spontaneous abortion, and fertility disorders, or with a protective role in HPV-related cervical carcinogenesis. Noteworthy, recent reports have identified AAV insertional mutagenesis as a novel risk factor for the development of hepatocellular carcinoma. This latest finding raises concern regarding the widespread usage of AAV vectors in liver-targeted gene therapy.

Harnessing the Natural Biology of Adeno-Associated Virus to Enhance the Efficacy of Cancer Gene Therapy

Adeno-associated virus (AAV) was first characterized as small “defective” contaminant particles in a simian adenovirus preparation in 1965. Since then, a recombinant platform of AAV (rAAV) has become one of the leading candidates for gene therapy applications resulting in two FDA-approved treatments for rare monogenic diseases and many more currently in various phases of the pharmaceutical development pipeline. Herein, we summarize rAAV approaches for the treatment of diverse types of cancers and highlight the natural anti-oncogenic effects of wild-type AAV (wtAAV), including interactions with the cellular host machinery, that are of relevance to enhance current treatment strategies for cancer.

The Interplay between Adeno-Associated Virus and its Helper Viruses

The adeno-associated virus (AAV) is a small, nonpathogenic parvovirus, which depends on helper factors to replicate. Those helper factors can be provided by coinfecting helper viruses such as adenoviruses, herpesviruses, or papillomaviruses. We review the basic biology of AAV and its most-studied helper viruses, adenovirus type 5 (AdV5) and herpes simplex virus type 1 (HSV-1). We further outline the direct and indirect interactions of AAV with those and additional helper viruses.

AAV Infection: Protection from Cancer

There are conflicting reports that integration of the wild-type adeno-associated virus 2 (AAV2) genome is associated with induction of hepatocellular carcinoma (HCC) in a small subset of patients. However, there are several lines of evidence that contradict this assertion: (i) AAV2 has long been known to be a non-pathogenic virus, although ∼90% of the human population is seropositive for AAV2 antibodies; (ii) AAV2 has been shown to possess anticancer activity; (iii) epidemiological evidence suggests that AAV2 infection plays a protective role against cervical carcinoma; and (iv) five different AAV serotype vectors (AAV1, AAV2, AAV5, AAV8, and AAV9) have been or are currently being used in 162 Phase I/II clinical trials and one Phase III clinical trial in humans to date, and no cancer of any type has ever been observed or reported. A brief historical account of the putative role of infection by AAV in the etiology of cancer, or lack thereof, is presented.

The interaction between human papillomavirus and other viruses

The etiological role of human papillomavirus (HPV) in anogenital tract and head and neck cancers is well established. However, only a low percentage of HPV-positive women develop cancer, indicating that HPV is necessary but not sufficient in carcinogenesis. Several biological and environmental cofactors have been implicated in the development of HPV-associated carcinoma that include immune status, hormonal changes, parity, dietary habits, tobacco usage, and co-infection with other sexually transmissible agents. Such cofactors likely contribute to HPV persistent infection through diverse mechanisms related to immune control, efficiency of HPV infection, and influences on tumor initiation and progression. Conversely, HPV co-infection with other factors may also harbor anti-tumor effects. Here, we review epidemiological and experimental studies investigating human immunodeficiency virus (HIV), herpes simplex virus (HSV) 1 and 2, human cytomegalovirus (HCMV), Epstein-Barr virus (EBV), BK virus (BKV), JC virus (JCV), and adeno-associated virus (AAV) as viral cofactors in or therapeutic factors against the development of genital and oral HPV-associated carcinomas.

Adeno-associated virus may play a protective role against human papillomavirus-induced cervical lesions independent of HIV serostatus

This study investigated the prevalence of adeno-associated virus (AAV) and human papillomavirus (HPV) DNA in cervical samples of HIV-seropositive and -seronegative women attending a clinic in south-eastern Brazil. Both viruses were investigated by polymerase chain reaction (PCR) and cytological exams were performed. AAV was typed by PCR and restriction fragment length polymorphism analysis. AAV prevalence was 19.7% (56/284), with 18.7% (21/112) and 20.3% (35/172) in HIV-positive and -negative women, respectively. AAV type 2 was the single virus type detected. AAV was detected with higher frequency in HPV-infected women ( P < 0.05) as was HPV in HIV-positive women ( P < 0.05). The AAV–HPV co-infected women showed a lower rate of atypical squamous cells of undetermined significance or cervical intraepithelial neoplasia development compared with those infected only with HPV. The prevalence of AAV2 confirms this type as the most common in human samples. This is the first report examining AAV in cervical samples of HIV-infected women and indicates that HIV infection does not appear to influence AAV prevalence or AAV–HPV co-infection.

Presence of DNA of adeno-associated virus in subfertile couples, but no association with fertility factors

BACKGROUND

Based on previous reports suggesting a role of adeno-associated virus (AAV) in miscarriage, the prevalence of AAV DNA in genital tracts of male and female partners of subfertile couples was determined to assess a potential association of AAV infection with clinically relevant parameters of male and female fertility.

METHODS

A prospective study was performed in the outpatient infertility clinic of a university-based hospital. Semen samples and endocervical material obtained from 146 male and 134 female partners of asymptomatic subfertile couples were analyzed for the presence of AAV DNA (using nested PCR). Patients' medical histories and details of clinical examinations were recorded. Semen quality, including sperm functional capacity and the presence of antisperm antibodies (ASA) and seminal white blood cells (WBC), was assessed in aliquots of the same ejaculate. Detailed examinations of the cervical factor and other variables of female subfertility were performed. Both partners were screened for bacterial infection.

RESULTS

The presence of AAV DNA in semen was not significantly related to semen quality, including sperm functional capacity or local ASA, nor was it coupled to the presence of AAV in the endocervical material of female partners. The presence of AAV DNA was not associated with the presence of other micro-organisms of the lower genital tract or with seminal WBC in men. AAV DNA in endocervical material was not related to a reduced quality of cervical mucus or to other female infertility factors.

CONCLUSIONS

The presence of AAV DNA in semen samples or endocervical swabs showed no significant association with clinically relevant infertility factors. However, longitudinal studies may clarify previous suggestions of an influence of AAV infection on early pregnancy problems.

HPV E1 up-regulates replication-related biochemistries of AAV Rep78

Human papillomavirus type 16 (HPV) E1 protein provides helper function for the adeno-associated virus type 2 (AAV) life cycle. E1 is the replication protein of HPV, analogous to AAV Rep78, but without the endonuclease/covalent attachment activity of Rep78. Previously we have shown that E1 and Rep78 interact in vitro. Here we investigated E1's effects on Rep78 interaction with AAV's inverted terminal repeat (ITR) DNA in vitro, using purified Rep78 and E1 proteins from bacteria. E1 enhanced Rep78-ITR binding, ATPase activity, Rep78-ITR-covalent linkage and Rep78-ITR-endonuclease activity (central to AAV replication). These enhancements occurred in a dose-dependent manner whenever assayed. However, overall Rep78-plus-E1 helicase activity was lower than Rep78's helicase activity. These data suggest that E1's broad-based helper function for the AAV life cycle (AAV DNA, mRNA, and protein levels are up-regulated by E1) is likely through its ability to enhance Rep78's critical replication-required biochemistries on ITR DNA.

Viral strategies for studying the brain, including a replication-restricted self-amplifying delta-G vesicular stomatis virus that rapidly expresses transgenes in brain and can generate a multicolor golgi-like expression

Viruses have substantial value as vehicles for transporting transgenes into neurons. Each virus has its own set of attributes for addressing neuroscience-related questions. Here we review some of the advantages and limitations of herpes, pseudorabies, rabies, adeno-associated, lentivirus, and others to study the brain. We then explore a novel recombinant vesicular stomatitis virus (dG-VSV) with the G-gene deleted and transgenes engineered into the first position of the RNA genome, which replicates only in the first brain cell infected, as corroborated with ultrastructural analysis, eliminating spread of virus. Because of its ability to replicate rapidly and to express multiple mRNA copies and additional templates for more copies, reporter gene expression is amplified substantially, over 500-fold in 6 hours, allowing detailed imaging of dendrites, dendritic spines, axons, and axon terminal fields within a few hours to a few days after inoculation. Green fluorescent protein (GFP) expression is first detected within 1 hour of inoculation. The virus generates a Golgi-like appearance in all neurons or glia of regions of the brain tested. Whole-cell patch-clamp electrophysiology, calcium digital imaging with fura-2, and time-lapse digital imaging showed that neurons appeared physiologically normal after expressing viral transgenes. The virus has a wide range of species applicability, including mouse, rat, hamster, human, and Drosophila cells. By using dG-VSV, we show efferent projections from the suprachiasmatic nucleus terminating in the periventricular region immediately dorsal to the nucleus. DG-VSVs with genes coding for different color reporters allow multicolor visualization of neurons wherever applied.

Cervical cancer isolate PT3, super-permissive for adeno-associated virus replication, over-expresses DNA polymerase delta, PCNA, RFC and RPA

BACKGROUND

Adeno-associated virus (AAV) type 2 is an important virus due to its use as a safe and effective human gene therapy vector and its negative association with certain malignancies. AAV, a dependo-parvovirus, autonomously replicates in stratified squamous epithelium. Such tissue occurs in the nasopharynx and anogenitals, from which AAV has been clinically isolated. Related autonomous parvoviruses also demonstrate cell tropism and preferentially replicate in oncogenically transformed cells. Combining these two attributes of parvovirus tropism, squamous and malignant, we assayed if AAV might replicate in squamous cervical carcinoma cell isolates.

RESULTS

Three primary isolates (PT1-3) and two established cervical cancer cell lines were compared to normal keratinocytes (NK) for their ability to replicate AAV. One isolate, PT3, allowed for high levels of AAV DNA replication and virion production compared to others. In research by others, four cellular components are known required for in vitro AAV DNA replication: replication protein A (RPA), replication factor C (RFC), proliferating cell nuclear antigen (PCNA), and DNA polymerase delta (POLD1). Thus, we examined PT3 cells for expression of these components by DNA microarray and real-time quantitative PCR. All four components were over-expressed in PT3 over two representative low-permissive cell isolates (NK and PT1). However, this super-permissiveness did not result in PT3 cell death by AAV infection.

CONCLUSION

These data, for the first time, provide evidence that these four cellular components are likely important for AAV in vivo DNA replication as well as in vitro. These data also suggest that PT3 will be a useful reagent for investigating the AAV-permissive transcriptome and AAV anti-cancer effect.

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.

No evidence for tumorigenesis of AAV vectors in a large-scale study in mice

Six hundred ninety-five mice received adeno-associated virus (AAV) vectors, mostly via portal vein injection. At necropsy, the livers were inspected for tumors, and tissue sections were prepared for histology. We observed only one tumor, a lipoma, resulting in a tumor frequency of 0.14%. This tumor contained fewer vector genomes per total DNA than the surrounding liver tissue, as shown by quantitative PCR. In another mouse we found a macroscopically visible nodule containing lymphocytes. Immunohistochemistry revealed cells not of monoclonal origin, and they contained fewer AAV genomes than the surrounding hepatocytes. There were no macroscopic tumors in 226 control mice. Upon microscopic examination, lymphocytic infiltrates were found in 5% of livers of both control and vector-treated mice; no transgene expression was seen in those infiltrates in AAV-injected animals. Compared to an average frequency of spontaneous liver tumors in C57BL/6 mice (0-10%), and given the absence of high levels of vector DNA in the observed tumor, we conclude that AAV vectors do not predispose these target animals to the formation of liver tumors.

Inhibition of atherogenesis in LDLR knockout mice by systemic delivery of adeno-associated virus type 2-hIL-10

Atherosclerosis is an inflammatory disease of the arteries. Interleukin-10 (IL-10) is known to be an anti-inflammatory cytokine which might be useful for counteracting the development of atherosclerosis. As long-term systemic cytokine delivery is prohibitively expensive, gene therapy might be a suitable approach. To test this idea, low-density lipoprotein receptor (LDLR) knockout mice were injected with recombinant adeno-associated virus type 2 (AAV)/interleukin-10 virus or AAV/granulocyte macrophage-colony stimulating factor (GM-CSF) virus and then put on a high-cholesterol diet. Upon harvesting the animals at 18 weeks, elevated blood lipids could be documented and AAV/IL-10 and AAV/GM-CSF DNA and mRNA could be found in various mouse organs. The mice receiving the AAV/IL-10 virus had significantly lower levels of atherogenesis (Sudan IV-staining and histology) than the untreated or the AAV/GM-CSF-treated animals, dropping from 53% to 17% (p < 0.05). The aortas of the AAV/IL-10-treated animals displayed higher IL-10 expression and lower CD68 and nitrotyrosine expression. These data are similar to those of Yoshioka et al. [Yoshioka, T, Okada, T, Maeda, Y, et al. Adeno-associatedvirus vector-mediated interleukin-10 gene transfer inhibits atherosclerosis in apolipoprotein E-deficient mice. Gene Ther 2004;11:1772-9] in which AAV/IL-10 was delivered into the tibial muscle of ApoE-deficient mice, instead of tail vein injection used here. These data indicate that systemic AAV/IL-10 gene delivery, with resulting inhibition of inflammation and oxidative stress, was able to limit atherogenesis, and suggest that this approach is worthy of further study.

Multiple human papillomavirus genes affect the adeno-associated virus life cycle

The risk of cervical cancer, one of the most prevalent cancers in the world, is determined by two viruses. Human papillomavirus (HPV) is the main risk factor for developing cervical cancer. However, although little known, it is well substantiated that the human Parvovirus adeno-associated virus type 2 (AAV), and its encoded Rep78 protein, interacts with HPV and lowers the risk of cervical cancer. HPV also contributes to AAV inhibition by serving as a helper virus for AAV and stimulating higher AAV replication levels. Here we surveyed four HPV-16 early genes, E1, E2, E6 and E7, for their ability to increase/decrease the basal level of AAV replication in stratifying squamous epithelium (the epithelial raft culture system). It was found that the HPV-16 E1, E2 and E6 genes were able to help/enhance AAV-2 replication in epithelial raft cultures. Under these conditions, with all the HPV genes being expressed from the AAV p5 promoter, E1 appeared to have the strongest enhancing effect on AAV DNA replication (Southern blot), RNA expression (RT-PCR), protein expression (Western blot) and AAV virion production (2 plate-Southern blot). Further study of E1 mutants showed that the carboxy-half of E1, the putative helicase/ATPase domain, was the main contributor of helper activity. These data are important for understanding the HPV-AAV interaction and its effect on modifying cervical cancer risk. These data also suggest the possibility that the identified HPV helper genes may be useful in the generation of recombinant (r)AAV virions for gene therapy, as rAAV is increasing in popularity for such purposes.

Human papillomavirus, cytomegalovirus, and adeno-associated virus infections in pregnant and nonpregnant women with cervical intraepithelial neoplasia

Two hundred eight cervical specimens from two groups of subjects, 165 nonpregnant women and 53 pregnant women with cervical intraepithelial neoplasia (CIN) of grades I to III, were positive by PCR analyses for human papillomaviruses (HPVs), adeno-associated virus type 2 (AAV 2), and human cytomegalovirus (HCMV) in 67, 6, and 4.1% of the cases, respectively. The presence of AAV 2 infection was more frequently associated with pregnancy (17 versus 2.4%) and HPV-positive cervices (odds ratio = 6.358) than HCMV was. Increased HPV infection was strongly associated (P < 0.001) with a higher CIN grade, but there is no evidence that AAV 2 and HCMV infections have any impact on CIN development.

Non-small lung cancer cells are prime targets for p53 gene transfer mediated by a recombinant adeno-associated virus type-2 vector

In this study, we elucidated the potential of recombinant adeno-associated virus type-2 (rAAV-2) vectors for lung cancer gene therapy. Cell lines of the three major histological subtypes of non-small cell lung cancer (NSCLC) were highly susceptible for rAAV-2 showing transduction rates between 63.4 and 98.9%. In contrast, cell lines of small cell carcinomas were resistant to rAAV-2 infection. For restoration of p53 function in p53 deficient NSCLC, a rAAV-2 vector was constructed containing wt p53 cDNA. Following transduction with rAAV-p53, cell growth of all NSCLC cell lines was significantly reduced in a dose-dependent manner between 44 and 71.7% in comparison with rAAV-GFP transduced cells. The reduction of tumor cell growth was associated with increased apoptosis. Adding cisplatin to rAAV-p53-infected cells led to a significant growth inhibition between 81 and 91% indicating a synergistic effect between cisplatin and rAAV-p53. Interestingly, the tumor cells surviving cisplatin and rAAV-p53 treatment were inhibited in their ability to form colonies as reflected by a reduction of colony growth between 57 and 90.4%. In conclusion, rAAV-2 vectors exhibit a strong tropism for NSCLC. Successful inhibition of tumor cell growth following transduction with a rAAV-p53 vector underlines the potential role of rAAV-2 in cancer gene therapy.

The adeno-associated virus major regulatory protein Rep78-c-Jun-DNA motif complex modulates AP-1 activity

Multiple epidemiologic studies show that adeno-associated virus (AAV) is negatively associated with cervical cancer (CX CA), a cancer which is positively associated with human papillomavirus (HPV) infection. Mechanisms for this correlation may be by Rep78's (AAV's major regulatory protein) ability to bind the HPV-16 p97 promoter DNA and inhibit transcription, to bind and interfere with the functions of the E7 oncoprotein of HPV-16, and to bind a variety of HPV-important cellular transcription factors such as Sp1 and TBP. c-Jun is another important cellular factor intimately linked to the HPV life cycle, as well as keratinocyte differentiation and skin development. Skin is the natural host tissue for both HPV and AAV. In this article it is demonstrated that Rep78 directly interacts with c-Jun, both in vitro and in vivo, as analyzed by Western blot, yeast two-hybrid cDNA, and electrophoretic mobility shift-supershift assay (EMSA supershift). Addition of anti-Rep78 antibodies inhibited the EMSA supershift. Investigating the biological implications of this interaction, Rep78 inhibited the c-Jun-dependent c-jun promoter in transient and stable chloramphenicol acetyl-transferase (CAT) assays. Rep78 also inhibited c-Jun-augmented c-jun promoter as well as the HPV-16 p97 promoter activity (also c-Jun regulated) in in vitro transcription assays in T47D nuclear extracts. Finally, the Rep78-c-Jun interaction mapped to the amino-half of Rep78. The ability of Rep78 to interact with c-Jun and down-regulate AP-1-dependent transcription suggests one more mechanism by which AAV may modulate the HPV life cycle and the carcinogenesis process.

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.

Human papillomavirus and cervical cancer

Of the many types of human papillomavirus (HPV), more than 30 infect the genital tract. The association between certain oncogenic (high-risk) strains of HPV and cervical cancer is well established. Although HPV is essential to the transformation of cervical epithelial cells, it is not sufficient, and a variety of cofactors and molecular events influence whether cervical cancer will develop. Early detection and treatment of precancerous lesions can prevent progression to cervical cancer. Identification of precancerous lesions has been primarily by cytologic screening of cervical cells. Cellular abnormalities, however, may be missed or may not be sufficiently distinct, and a portion of patients with borderline or mildly dyskaryotic cytomorphology will have higher-grade disease identified by subsequent colposcopy and biopsy. Sensitive and specific molecular techniques that detect HPV DNA and distinguish high-risk HPV types from low-risk HPV types have been introduced as an adjunct to cytology. Earlier detection of high-risk HPV types may improve triage, treatment, and follow-up in infected patients. Currently, the clearest role for HPV DNA testing is to improve diagnostic accuracy and limit unnecessary colposcopy in patients with borderline or mildly abnormal cytologic test results.

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.

Circulating tumour necrosis factor-alpha and interferon-gamma are detectable during acute and convalescent parvovirus B19 infection and are associated with prolonged and chronic fatigue

To investigate whether cytokine responses may have a bearing on the symptoms and outcome of parvovirus B19 infection, circulating cytokines were measured during acute infection (n=51), follow-up of acute infection (n=39) and in normal healthy controls (n=50). At acute B19 virus infection (serum anti-B19 IgM-positive), patients ranged in age from 4 to 54 years, with a mean age of 28.2 years. The male:female ratio was 1:4.1 and symptoms were rash (n=15), arthralgia (n=31), fatigue (n=8), lymphadenopathy (n=4), foetal hydrops (n=3), transient aplastic crisis (n=2), neutropenia (n=2), myelodysplasia (n=1), thrombocytopenia (n=1) and pancytopenia (n=1). Of these patients, 39 were contacted after a follow-up period of 2-37 months (mean of 22.5 months). In comparison with normal controls, detectable IL-6 was associated with acute B19 virus infection (26%; P=0.0003), but not with follow-up (6%; P=0.16). Detection of interferon (IFN)-gamma was associated with acute B19 virus infection (67%; P<0.0001) and follow-up (67%; P<0.0001). Detection of tumour necrosis factor (TNF)-alpha was associated with acute B19 virus infection (49%; P<0.0001) and follow-up (56%; P<0.0001). IL-1beta was detected in acute infection (20%), but not at follow-up. At acute B19 virus infection, detection of serum/plasma IL-6 was associated with rheumatoid factor (P=0.038) and IFN-gamma (> or =7 pg/ml) was associated with fatigue in those patients of > or =15 years of age (P=0.022). At follow-up, fatigue was associated with IFN-gamma (> or =7 pg/ml) and/or TNF-alpha (> or =40 pg/ml) (P=0.0275). Prolonged upregulation of serum IFN-gamma and TNF-alpha appears to represent a consistent host response to symptomatic B19 virus infection.

DNA of adeno-associated virus (AAV) in testicular tissue and in abnormal semen samples

BACKGROUND

Human genital tissues, including spermatozoa, have been found to be frequently infected with the helper-virus dependent parvovirus, adeno-associated virus (AAV).

METHODS

To assess the role of AAV infection in disorders of the male reproductive system, semen samples from 95 men (including 73 men attending a fertility programme) and testicular samples from patients with azoospermia (n = 38) or prostate cancer (n = 8) were analysed using polymerase chain reaction for the presence of AAV DNA. Semen quality was assessed according to World Health Organization guidelines and the grade of atrophy of testicular biopsies was determined histomorphologically.

RESULTS

AAV DNA was detected in 38% (28/73) of ejaculates from men with abnormal semen analyses (oligoasthenozoospermia or asthenozoospermia) and in 4.6% of normal semen samples (1/22, P = 0.003). DNA from AAV helper-viruses (human papillomaviruses, cytomegalovirus) was detected at similar frequencies in normal and abnormal semen samples. In testes, AAV DNA was detected in 10 out of 38 biopsies from infertile men (26%), and in 2 out of 8 orchidectomy samples.

CONCLUSION

The data show an increased incidence of AAV infection with abnormal semen analysis. Detection of AAV DNA in the testes might point to a role for AAV infection in male infertility, possibly by interfering with spermatozoa development.

Altered biology of adeno-associated virus type 2 and human papillomavirus during dual infection of natural host tissue

Adeno-associated virus (AAV), a common genital virus, may have a "protective" role against human papillomavirus (HPV)-associated cervical cancer. Epidemiological studies indicate a negative correlation between AAV infection and the incidence of cervical cancer. In contrast, HPV is positively associated with cervical cancer. To investigate interactions between these two viruses we used the organotypic "raft" culture system. The raft culture system is capable of supporting the complete HPV life cycle. Raft tissues that were actively replicating HPV were superinfected with AAV type 2 (AAV-2). We observed a multiplicity of infection (m.o.i.)-dependent enhancement and inhibition of HPV DNA replication, concomitant with AAV-2 replication. The data suggest that at low m.o.i. of AAV-2 infection, HPV DNA replication was slightly increased compared to controls and AAV-2 replicated poorly. At high AAV-2 m.o.i., HPV DNA replication was reduced and AAV-2 replicated to high levels. AAV-2 replication was increased in the presence of HPV compared to primary human keratinocyte, squamous cell carcinoma, and HaCat raft cultures infected with AAV-2 alone. These data suggest that HPV may provide types of "enhancer/helper" functions for AAV-2 replication and progeny formation. Infection with AAV-2 had significant effects on epithelial morphology. During infection with low m.o.i. of AAV-2 the epithelium stratified to a greater extent than in controls. With high m.o.i. of AAV-2 infections, tissue cytopathic effects were observed, indicating an additional factor responsible for the effect of AAV-2 on HPV replication and infection. Our results demonstrate a complex interaction between AAV-2, HPV, and skin during dual infection.