Polyadenylation of genomic RNA and initiation of antigenomic RNA in a positive-strand RNA virus are controlled by the same cis-element

Genomes and antigenomes of many positive-strand RNA viruses contain 3'-poly(A) and 5'-poly(U) tracts, respectively, serving as mutual templates. Mechanism(s) controlling the length of these homopolymeric stretches are not well understood. Here, we show that in coxsackievirus B3 (CVB3) and three other enteroviruses the poly(A) tract is approximately 80-90 and the poly(U) tract is approximately 20 nt-long. Mutagenesis analysis indicate that the length of the CVB3 3'-poly(A) is determined by the oriR, a cis-element in the 3'-noncoding region of viral RNA. In contrast, while mutations of the oriR inhibit initiation of (-) RNA synthesis, they do not affect the 5'-poly(U) length. Poly(A)-lacking genomes are able to acquire genetically unstable AU-rich poly(A)-terminated 3'-tails, which may be generated by a mechanism distinct from the cognate viral RNA polyadenylation. The aberrant tails ensure only inefficient replication. The possibility of RNA replication independent of oriR and poly(A) demonstrate that highly debilitated viruses are able to survive by utilizing 'emergence', perhaps atavistic, mechanisms.

Abnormal cervical cytology in women eligible for IVF

BACKGROUND

Chlamydia trachomatis is more prevalent in subfertile women than in the general population and is the leading cause of tubal factor subfertility. As C. trachomatis infections are sexually transmitted, it can be expected that infections with human papillomavirus (HPV) are also more prevalent in this group of women. HPV is a necessary cause for the development of cervical (pre-)malignancies. We therefore hypothesized that subfertile women are more likely to have HPV-induced cervical abnormalities compared to the general population.

METHODS

In this retrospective case-control study, all cervical smears of women visiting the fertility clinic for IVF (cases) and of women attending the population-based screening programme for cervical cancer (controls) were retrieved from an electronic database and assessed.

RESULTS

The cases (n = 669) showed significantly more abnormal cervical smears compared to the controls (77,055) (6.1 and 3.9%, respectively, P < 0.02).

CONCLUSIONS

The probability that subfertile women eligible for IVF are diagnosed with a high-grade cervical lesion is almost twice as high compared to women in the general population. We therefore suggest to take a cervical smear from all women referred for fertility problems.

In vitro release by Aspergillus fumigatus of galactofuranose antigens, 1,3-beta-D-glucan, and DNA, surrogate markers used for diagnosis of invasive aspergillosis

Aspergillus markers are becoming increasingly important for the early diagnosis of invasive aspergillosis. The kinetics of release of these surrogate markers, however, is largely unknown. We investigated the release of beta-(1-5)-galactofuranosyl (galf) antigens (Platelia Aspergillus), 1,3-beta-D-glucan (BG) (Fungitell), and DNA (PCR) in an in vitro model of Aspergillus fumigatus. The results showed that release is correlated to the growth phase of the fungus, which depends on available nutrients. Whereas galf antigens and BG are released during logarithmic growth, DNA is released only after mycelium breakdown. During early logarithmic growth, galf antigens seem to be released somewhat earlier than BG. Furthermore, galf antigen concentrations of more than 120,000 times the serum cutoff value (0.5 ng/ml) can be measured, while BG concentrations reach a value only 978 times the serum cutoff value (60 pg/ml). During lytical growth, release of galf antigens further increased to a maximum level, which depended on pH. After that, the concentration of galf antigens stayed high (pH 7.4) or decreased to zero within 4 days (pH 5.0). In contrast to galf antigens, BG concentration decreased after 1 day of growth. The decrease of galf components seems to be due to the enzyme beta-galactofuranosidase, which is able to destroy galf epitopes and whose activity fluctuates in the culture filtrates in parallel with galf antigen concentration. Fungal DNA seems to be released only due to autolysis caused by nutrient limitation. In conclusion, several factors clearly influence the release of surrogate markers in vitro. These same factors might also play a role at the infection site of Aspergillus disease in humans.

Structural and functional integrity of the coxsackievirus B3 oriR: spacing between coaxial RNA helices

The enterovirus oriR is composed of two helices, X and Y, anchored by a kissing (K) interaction. For proper oriR function, certain areas of these helices should be specifically oriented towards each other. It was hypothesized that the single-stranded nucleotides bridging the coaxial helices (Y-X and K-Y linkers) are important to determine this orientation. Spatial changes were introduced by altering the linker length between the helices of the coxsackievirus B3 oriR. Changing the linker lengths resulted in defective RNA replication, probably because of an altered oriR geometry. The identity of the linker residues also played a role, possibly because of sequence-specific ligand recognition. Although each point mutation altering the primary sequence of the Y-X spacer resulted in defective growth at 36 degrees C, the mutations had a wild-type phenotype at 39 degrees C, indicating a cold-sensitive phenotype. The results show that the intrinsic connection between oriR structure and function is fine-tuned by the spacing between the coaxial RNA helices.

Structural and functional characterization of the coxsackievirus B3 CRE(2C): role of CRE(2C) in negative- and positive-strand RNA synthesis

A stem-loop element located within the 2C-coding region of the coxsackievirus B3 (CVB3) genome has been proposed to function as a cis-acting replication element (CRE). It is shown here that disruption of this structure indeed interfered with viral RNA replication in vivo and abolished uridylylation of VPg in vitro. Site-directed mutagenesis demonstrated that the previously proposed enteroviral CRE consensus loop sequence, R(1)NNNAAR(2)NNNNNNR(3), is also applicable to CVB3 CRE(2C) and that a positive correlation exists between the ability of CRE(2C) mutants to serve as template in the uridylylation reaction and the capacity of these mutants to support viral RNA replication. To further investigate the effects of the mutations on negative-strand RNA synthesis, an in vitro translation/replication system containing HeLa S10 cell extracts was used. Similar to the results observed for poliovirus and rhinovirus, it was found that a complete disruption of the CRE(2C) structure interfered with positive-strand RNA synthesis, but not with negative-strand synthesis. All CRE(2C) point mutants affecting the enteroviral CRE consensus loop, however, showed a marked decrease in efficiency to induce negative-strand synthesis. Moreover, a transition (A(5)G) regarding the first templating adenosine residue in the loop was even unable to initiate complementary negative-strand synthesis above detectable levels. Taken together, these results indicate that the CVB3 CRE(2C) is not only required for the initiation of positive-strand RNA synthesis, but also plays an essential role in the efficient initiation of negative-strand RNA synthesis, a conclusion that has not been reached previously by using the cell-free system.

Long-term follow-up after large-loop excision of the transformation zone: evaluation of 22 years treatment of high-grade cervical intraepithelial neoplasia

Early treatment of cervical intraepithelial neoplasia (CIN) significantly reduces the risk of invasive cancerous progression. Residual and recurrent high-grade CIN should be detected and retreated in an early phase. Therefore, a postsurgery cytologic follow-up protocol was introduced at 3, 6, 9, and 12 months and yearly thereafter for 5 years. The aim of this study is to evaluate the long-term experience in treating high-grade CIN using large-loop excision of the transformation zone (LLETZ). Additionally, the long-term follow-up in this study gains the opportunity to document the pattern of disease recurrence beyond 5 years. The average follow-up of the 1696 women included in this study was 6.5 years. Overall, 8.5% of the patients who underwent LLETZ showed a high-grade repetitive CIN and three patients had invasive carcinoma. Eighty percent of those lesions were probably residual, whereas 20% of all high-grade repetitive lesions appeared more than 2 years after initial surgery and were considered recurrent lesions. Half of the recurrent lesions occurred more than 5 years after LLETZ.

Effects of HPV detection in population-based screening programmes for cervical cancer; a Dutch moment

Presently, large randomised studies are investigating the value of incorporating HPV detection in population-based cervical screening programmes to improve the effectiveness of these programmes. None of these studies, however, has assessed the effect of HPV detection on the participation rate of women in these screening programmes. This paper draws attention to the fact that the effectiveness of cervical screening largely depends on the participation rate. A number of possibilities will be addressed on how HPV may affect cervical cancer screening. On the one hand, an option is described that addition of HPV detection, although increasing the sensitivity of screening, may in fact decrease the overall effectiveness of the screening. On the other hand, the possibility is put forward that incorporation of HPV will increase the reduction in mortality because of increased sensitivity and participation to the screening. Our manuscript thereby addresses an important aspect of screening, namely, the societal impact of new diagnostic tests on coverage in population-based screening programmes.

p14ARF and p16INK4A, two products of the same gene, are differently expressed in cervical intraepithelial neoplasia

OBJECTIVE

To study the expression patterns of two different tumor suppressor proteins p16INK4A and p14ARF in cervical lesions. Both proteins are encoded by the same INK4A/ARF gene on chromosome 9p21. The expression patterns of these two proteins, both playing a central role in the cell cycle, were analyzed in detail in CIN, carcinomas, and normal epithelium to test the hypothesis that p16INK4A positive cells also demonstrate p14ARF expression.

METHODS

Serial tissue sections of 9 CIN1 lesions, 10 CIN2 lesions, 12 CIN3 lesions, and 7 carcinomas were stained with monoclonal antibodies against p16INK4A and p14ARF. The short fragment polymerase chain reaction hybridization line probe assay was used to detect HPV.

RESULTS

Normal epithelium was negative for both proteins. Marked immunoreactivity (++) for p16INK4A and p14ARF was observed in 5/7 carcinomas, 10/12 CIN3, and 1/10 CIN2 lesions and 0/9 CIN1 lesions. Simultaneous expression (+ or ++) was found in 19/22 CIN2/3 and not in CIN1 lesions. The fraction of p16INK4A-stained cells increased with CIN-grade. Overexpression of p14ARF was observed in a subpopulation of p16INK4A positive cells, and exclusively found in lesions infected with high-risk HPV. In two CIN3 lesions with early stromal invasion, p14ARF positivity was mainly found in the invasive cells. In carcinomas, all cells showed p16INK4A expression, whereas p14ARF was limited to the peripheral cells of the invasive tumor nests and individual migrating tumor cells.

CONCLUSIONS

Overexpression of p14ARF is limited to a fraction of the p16INK4A-expressing cells and therefore it is likely that p14ARF- and p16INK4A expression are not induced by the same mechanisms. Before expression of p14ARF can be linked to invasion or invasive phenotype, larger series of (micro-) invasive squamous lesions need to be studied.

Alternaria infectoriaphaeohyphomycosis in a renal transplant patient

A male renal transplant patient developed a tumor on the dorsum of his right hand. After excision, histological examination of the tumor showed hyphal structures, but growth developed very slowly. Therapy consisted of surgery alone. A definitive identification of Alternaria infectoria was only possible with molecular techniques.

Vulvar Squamous Cell Carcinoma is a Multifactorial Disease Following Two Separate and Independent Pathways

Two separate pathways leading to vulvar carcinoma have been suggested. First, a human papillomavirus (HPV)-dependent pathway, in which premalignant stages of vulvar cancer are the classic vulvar intraepithelial neoplasia (VIN) lesions. Second, an HPV-independent pathway, associated with differentiated VIN III lesions and/or lichen sclerosus. To obtain insight into the mechanisms underlying these pathways, we determined the relationship between HPV DNA and the expression of p14(ARF) and p16(INK4A) in non- and (pre)malignant vulvar lesions. Seventy-three archival samples of non- and (pre)neoplastic vulvar lesions were selected and tested for hr-HPV DNA using a broad-spectrum HPV detection/genotyping assay (SPF(10)-LiPA) and the expression of p14(ARF) and p16(INK4A). The prevalence of HPV increased with the severity of the classic VIN lesions; in VIN I no hr-HPV was detected, in VIN II 43%, and in VIN III 71% of the samples were hr-HPV-positive. Roughly the same was true for the expression of p14(ARF) and p16(INK4A). The simultaneous expression of p14(ARF) and p16(INK4A) was highly associated with the presence of hr-HPV DNA. Hr-HPV was detected in only a single case of the differentiated VIN III lesions, whereas no expression of p14(ARF) was found and 16(INK4A) was present in only two cases. All 16 samples of vulvar cancer were hr-HPV DNA- negative, although in respectively 63% and 25%, p14(ARF) and p16(INK4A) was expressed. No relation was found between hr-HPV and the expression of p14(ARF) and p16(INK4A) in the 20 nonneoplastic vulvar lesions. Our results provide further evidence that vulvar squamous cell carcinoma is a multifactorial disease that develops from two different pathways. First, an HPV-dependent pathway with a remarkable resemblance to CIN lesions and cervical carcinoma and second, an HPV-independent pathway in which differentiated VIN III lesions that are hr-HPV-negative may be precursors.

Coxsackie B virus infection of mice: inoculation by the oral route protects the pancreas from damage, but not from infection

The pathogenesis of coxsackie B virus (CVB) infections is generally studied in mice by intraperitoneal (i.p.) injection, whereas the gastrointestinal tract is the natural porte d'entrée in humans. The present study was undertaken to compare systematically the influence of infection route on morbidity and pathology. Swiss Albino mice were infected with CVB3 (Nancy) at different doses (5 x 10(3), 5 x 10(5), 5 x 10(7), 5 x 10(9) TCID50), given either i.p. or orally. Virus could be isolated from several organs (heart, spleen and pancreas), indicating systemic infection, irrespective of the infection route. Virus titres were 1-2 logs higher after i.p. infection, but kinetics were largely independent of infection route. Organs became negative for virus isolation after 21 days, with the exception of spleen tissue, which remained positive for up to 49 days. Thereafter, virus was detected only by immunohistochemistry and PCR up to 98 days post-infection (oral route). Histopathology showed mild inflammation and necrosis in heart tissue of all mice during the acute phase, with repair at later stages. Strikingly, pancreatic lesions were confined to the exocrine pancreas and observed only after i.p. infection. Under all experimental conditions, the pancreatic islets were spared. In contrast, immunohistochemistry showed the presence of viral VP1, protein 3A and alpha interferon (IFN-alpha) in exocrine as well as endocrine pancreas of all mice, irrespective of route and dose of infection. It is concluded that infection via the oral route protects the pancreas from damage, but not from infection, a process in which IFN-alpha is not the only factor involved.

The incidence of congenital cytomegalovirus infections in The Netherlands

Cytomegalovirus (CMV) is one of the most common causes of congenital infection without an effective treatment or an effective vaccine available to date. The emphasis has to be on preventive strategies, which rely on the epidemiological situation. The incidence of congenital CMV infections, however, is not known for The Netherlands. Therefore, a prospective virological study was carried out in a population of 7,524 pregnant women and 7,793 newborns. CMV-specific IgG antibodies were determined in cord blood by ELISA. When CMV antibodies were present, a CMV specific PCR was performed on the throat swab. A positive PCR was confirmed by urine culture. In addition, the seroepidemiology for CMV was investigated in the metropolitan region (Amsterdam and Rotterdam) which has a different ethnic composition. Congenital CMV infection was found in 7 infants (0.9 per 1,000). None had symptoms at birth or during 24 month follow-up. Carriage or CMV was 41%, with a variation between 35% and 100% depending on ethnicity. The ethnic composition in the south-eastern region was different from that in large cities, but similar to that in the rest of the country. The incidence of congenital CMV infections in The Netherlands is the lowest described to date, which does not justify special preventive policies.

Toxoplasmosis after renal transplantation: implications of a missed diagnosis

We describe a renal transplant patient with a primary Toxoplasma gondii infection presenting as pneumonitis, with subsequent chorioretinitis and encephalitis. The diagnostic challenges of T. gondii infection in immunocompromised patients are discussed.

comparison of two commercial assays for detection of human papillomavirus (HPV) in cervical scrape specimens: validation of the Roche AMPLICOR HPV test as a means to screen for HPV genotypes associated with a higher risk of cervical disorders

Certain high-risk (HR) human papillomavirus (HPV) types are a necessary cause for the development of cervical disorders. Women with persistent HR HPV infections have an increased risk of developing high-grade cervical lesions, compared with those who have no or low-risk HPV infections. Therefore, implementation of HPV detection into cervical screening programs might identify women at risk of cervical cancer. Several HPV detection methods with different sensitivities and specificities are available. Recently, a new PCR-based technique, the Roche AMPLICOR HPV Test, was developed. This test recognizes a group of 13 HR HPV types simultaneously. This study was undertaken to validate and compare HPV detection in 573 cervical scrape specimens by the AMPLICOR HPV Test and the INNO-LiPA HPV detection/genotyping assay (SPF10-LiPA system version 1). Human beta-globin was not detected in nine specimens, which were therefore excluded from the comparison. Eleven scrape specimens containing HPV type 53 or 66 were also excluded from the comparison because these (probably) HR HPV types cannot be detected by the AMPLICOR HPV Test. The results of HPV detection by the Roche AMPLICOR HPV Test were confirmed by INNO-LiPA HPV detection/genotyping assay in 539/553 cases, showing an absolute agreement of 97.5% with a Cohen's kappa of 0.9327, indicating almost complete similarity of the two tests. Like the INNO-LiPA HPV detection/genotyping assay, the AMPLICOR HPV Test was sensitive, specific, feasible, and easy to handle. The value of the Roche AMPLICOR HPV Test with a broad-spectrum HR HPV detection has to be determined in prospective clinical studies.

Chlamydia trachomatis and genital human papillomavirus infections in female university students in Honduras

Sexually transmitted infections are a serious health problem in Honduras. Human papillomavirus (HPV) and Chlamydia trachomatis are major causes of sexually transmitted diseases. To determine the prevalence of C. trachomatis and HPV in young women, 100 female university students in Honduras were assayed for the presence of these pathogens. Twenty-eight percent were positive for HPV and 6% were positive for C. trachomatis. These results show that genital HPV and C. trachomatis infections are very common among sexually active young women in Honduras. It is vital to promote extensive public awareness campaigns among sexually active women concerning preventive measures of these diseases.

A proline-rich region in the coxsackievirus 3A protein is required for the protein to inhibit endoplasmic reticulum-to-golgi transport

The ability of the 3A protein of coxsackievirus B (CVB) to inhibit protein secretion was investigated for this study. Here we show that the ectopic expression of CVB 3A blocked the transport of both the glycoprotein of vesicular stomatitis virus, a membrane-bound secretory marker, and the alpha-1 protease inhibitor, a luminal secretory protein, at a step between the endoplasmic reticulum (ER) and the Golgi complex. CVB 3A contains a conserved proline-rich region in its N terminus. The importance of this proline-rich region was investigated by introducing Pro-to-Ala substitutions. The mutation of Pro19 completely abolished the ability of 3A to inhibit ER-to-Golgi transport. The mutation of Pro14, Pro17, or Pro20 also impaired this ability, but to a lesser extent. The mutation of Pro18 had no effect. We also investigated the possible importance of this proline-rich region for the function of 3A in viral RNA replication. To this end, we introduced the Pro-to-Ala mutations into an infectious cDNA clone of CVB3. The transfection of cells with in vitro-transcribed RNAs of these clones gave rise to mutant viruses that replicated with wild-type characteristics. We concluded that the proline-rich region in CVB 3A is required for its ability to inhibit ER-to-Golgi transport, but not for its function in viral RNA replication. The functional relevance of the proline-rich region is discussed in light of the proposed structural model of 3A.

Enterovirus protein 2B po(u)res out the calcium: a viral strategy to survive?

Enteroviruses modify several cellular functions to ensure efficient replication. However, some of these alterations can trigger a defensive apoptotic host-cell program. To prevent premature abortion of their productive cycle, enteroviruses have developed anti-apoptotic countermeasures. Here, we discuss recent evidence that the enterovirus 2B protein exerts an anti-apoptotic activity that is related to its ability to form pores in endoplasmic reticulum (ER) and Golgi membranes, thereby reducing their Ca(2+) content and perturbing ER-mitochondrial Ca(2+) signaling.

Influenza-associated encephalopathy: no evidence for neuroinvasion by influenza virus nor for reactivation of human herpesvirus 6 or 7

During 2 consecutive influenza seasons we investigated the presence of influenza virus, human herpesvirus (HHV) type 6, and HHV-7 in cerebrospinal fluid samples from 9 white children suffering from influenza-associated encephalopathy. We conclude that it is unlikely that neuroinvasion by influenza virus or reactivation of either HHV-6 or HHV-7 is involved.

Down regulation of estrogen receptor expression is an early event in human papillomavirus infected cervical dysplasia

PURPOSE

To study the alterations in hormonal sensitivity in relation to proliferative activity during the development of cervical dysplasia in women infected with high-risk human papillomavirus (hr-HPV).

METHODS

Three to five biopsies of the cervix of eight patients were taken at colposcopy. Dysplasia was detected in 22 of the 32 biopsies, and 20 of these 22 biopsies contained hr-HPV. The labeling index (LI) as well as the intensity of staining of the MIB-1-, estrogen receptor (ER)-, and progesterone receptor (PR)-expression was assessed in each biopsy, including normal epithelium directly adjacent to the dysplastic lesions.

RESULTS

Statistical analysis showed a significant increase in the MIB-1 LI with increasing severity of the dysplasia. The ER LI and ER intensity of staining in dysplastic lesions, as well as in morphologically normal epithelium directly adjacent to the dysplasia, showed a significant inverse relation with the severity of the dysplasia. The PR LI and intensity of staining did not differ between normal epithelium and dysplasia. The ER/MIB-1 ratio (including the ER LI and ER intensity of staining), and the PR/MIB-1 ratio (intensity of staining only) in dysplastic lesions showed a significant inverse relation with the severity of the dysplasia, while no alterations in these ratios were observed in morphologically normal epithelium adjacent to the dysplasia.

CONCLUSION

Down regulation of ER expression may be the first alteration to take place in normal epithelium during the development of cervical dysplasia in women infected with hr-HPV. The significant decrease in the ER/MIB-1-, and PR/MIB-1-ratio in progressively dysplastic lesions indicates a loss of normal growth control by sex steroid hormones, which is not observed in normal epithelium.

Epidemiological and clinical aspects of human papillomavirus detection in the prevention of cervical cancer

Cervical cancer is a major cause of death, and the second most frequent cancer in women worldwide. Many studies have indicated a causal relation between genital human papillomavirus (HPV) infections and cervical cancer. High-risk HPV genotypes have been detected in almost 100% of all cervical cancers, and the process of HPV mediated carcinogenesis has been partly clarified. The concept that HPV is a obligatory cause in cervical cancer development has lead to extensive research regarding the incorporation of HPV detection in (1) cervical cancer prevention programs, (2) triage of women with abnormal cervical scrapes in the screening program, and (3) follow-up of patients treated for cervical intraepithelial neoplasia (CIN). Epidemiological studies indicate that 50% of women becoming sexually active contract a genital HPV infection within 2 years. The lifetime risk of a genital HPV infection is estimated to be 80%, but very few of these women will develop cervical cancer. Several studies have shown that the persistence of genital HPV infections is especially related to the development of cervical cancer. As a result, HPV detection at a single moment was shown to be of limited clinical value in the triage of patients with abnormal cervical scrapes, or during follow-up after treatment for CIN. Furthermore, major variations in the sensitivity of different HPV detection methods, as well as differences in HPV detection related to the menstrual cycle, have shown that many facts regarding HPV transmission, replication, and detection need to be clarified, before HPV detection can be of clinical value.

The coxsackievirus 2B protein suppresses apoptotic host cell responses by manipulating intracellular Ca2+ homeostasis

Enteroviruses, small cytolytic RNA viruses, confer an antiapoptotic state to infected cells in order to suppress infection-limiting apoptotic host cell responses. This antiapoptotic state also lends protection against cell death induced by metabolic inhibitors like actinomycin D and cycloheximide. The identity of the viral antiapoptotic protein and the underlying mechanism are unknown. Here, we provide evidence that the coxsackievirus 2B protein modulates apoptosis by manipulating intracellular Ca(2+) homeostasis. Using fluorescent Ca(2+) indicators and organelle-targeted aequorins, we demonstrate that ectopic expression of 2B in HeLa cells decreases the Ca(2+) content of both the endoplasmic reticulum and the Golgi, resulting in down-regulation of Ca(2+) signaling between these stores and the mitochondria, and increases the influx of extracellular Ca(2+). In our studies of the physiological importance of the 2B-induced alterations in Ca(2+) signaling, we found that the expression of 2B suppressed caspase activation and apoptotic cell death induced by various stimuli, including actinomycin D and cycloheximide. Mutants of 2B that were defective in reducing the Ca(2+) content of the stores failed to suppress apoptosis. These data implicate a functional role of the perturbation of intracellular Ca(2+) compartmentalization in the enteroviral strategy to suppress intrinsic apoptotic host cell responses. The putative down-regulation of an endoplasmic reticulum-dependent apoptotic pathway is discussed.

Mutational analysis of different regions in the coxsackievirus 2B protein: requirements for homo-multimerization, membrane permeabilization, subcellular localization, and virus replication

The coxsackievirus 2B protein is a small hydrophobic protein (99 amino acids) that increases host cell membrane permeability, possibly by forming homo-multimers that build membrane-integral pores. Previously, we defined the functional role of the two hydrophobic regions HR1 and HR2. Here, we investigated the importance of regions outside HR1 and HR2 for multimerization, increasing membrane permeability, subcellular localization, and virus replication through analysis of linker insertion and substitution mutants. From these studies, the following conclusions could be drawn. (i) The hydrophilic region ((58)RNHDD(62)) between HR1 and HR2 is critical for multimerization and increasing membrane permeability. Substitution analysis of Asn(61) and Asn(62) demonstrated the preference for short polar side chains (Asp, Asn), residues that are often present in turns, over long polar side chains (Glu, Gln). This finding supports the idea that the hydrophilic region is involved in pore formation by facilitating a turn between HR1 and HR2 to reverse chain direction. (ii) Studies undertaken to define the downstream boundary of HR2 demonstrated that the aromatic residues Trp(80) and Trp(82), but not the positively charged residues Arg(81), Lys(84), and Lys(86) are important for increasing membrane permeability. (iii) The N terminus is not required for multimerization but does contribute to the membrane-active character of 2B. (iv) The subcellular localization of 2B does not rely on regions outside HR1 and HR2 and does not require multimerization. (v) Virus replication requires both the membrane-active character and an additional function of 2B that is not connected to this activity.

Management of patients with two consecutive ASC-US smears

INTRODUCTION

To determine whether aggressive or expectative management of patients after two consecutive smears with atypical squamous cells of undetermined significance is preferable. To determine whether triage with high-risk human papillomavirus will identify all patients with cervical intraepithelial neoplasia grade 2 and 3.

METHODS

140 of 282 patients referred for colposcopy with two consecutive smears with atypical squamous cells of undetermined significance were only treated when abnormalities suggestive of high-grade cervical intraepithelial neoplasia were present at colposcopy. The other 142 patients underwent excision of all detected colposcopic abnormalities. Both groups were compared regarding the final cytological follow-up, the number of diathermy loop excisions, and the detection of cervical intraepithelial neoplasia. Retrospectively, the outcome of triage with high-risk human papillomavirus in the first group was investigated.

RESULTS

There was no significant difference in final cytological follow-up between patients managed by expectative or by aggressive colposcopic management. Significantly less diathermy loop excisions (p < 0.001) are performed in case of expectative management. The sensitivity, specificity, negative- and positive predictive values of triage with high-risk human papillomavirus detection were comparable with those of colposcopy alone.

CONCLUSIONS

Patients referred with two consecutive ASC-US smears may be followed with an expectative colposcopic management and cytological follow-up. Triage with high-risk human papillomavirus will reduce the number of referrals and colposcopies, but (cytological) follow-up remains necessary in all high-risk human papillomavirus negative patients as well.