Karin Edlund

Adenovirus Type 37 Uses Sialic Acid as a Cellular Receptor

ABSTRACT Two cellular receptors for adenovirus, coxsackievirus-adenovirus receptor (CAR) and major histocompatibility complex class I (MHC-I) α2, have recently been identified. In the absence of CAR, MHC-I α2 has been suggested to serve as a cellular attachment protein for subgenus C adenoviruses, while members from all subgenera except subgenus B have been shown to interact with CAR. We have found that adenovirus type 37 (Ad37) attachment to CAR-expressing CHO cells was no better than that to CHO cells lacking CAR expression, suggesting that CAR is not used by Ad37 during attachment. Instead, we have identified sialic acid as a third adenovirus receptor moiety. First, Ad37 attachment to both CAR-expresing CHO cells and MHC-I α2-expressing Daudi cells was sensitive to neuraminidase treatment, which eliminates sialic acid on the cell surface. Second, Ad37 attachment to sialic acid-expressing Pro-5 cells was more than 10-fold stronger than that to the Pro-5 subline Lec2, which is deficient in sialic acid expression. Third, neuraminidase treatment of A549 cells caused a 60% decrease in Ad37 replication in a fluorescent-focus assay. Moreover, the receptor sialoconjugate is most probably a glycoprotein rather than a ganglioside, since Ad37 attachment to sialic acid-expressing Pro-5 cells was sensitive to protease treatment. Ad37 attachment to Pro-5 cells occurs via α(2→3)-linked sialic acid saccharides rather than α(2→6)-linked ones, since (i) α(2→3)-specific but not α(2→6)-specific lectins blocked Ad37 attachment to Pro-5 cells and (ii) pretreatment of Pro-5 cells with α(2→3)-specific neuraminidase resulted in decreased Ad37 binding. Taken together, these results suggest that, unlike Ad5, Ad37 makes use of α(2→3)-linked sialic acid saccharides on glycoproteins for entry instead of using CAR or MHC-I α2.

Initial interactions of subgenus D adenoviruses with A549 cellular receptors : sialic acid versus alpha(v) integrins

ABSTRACT Selected members of the adenovirus family have been shown to interact with the coxsackie adenovirus receptor, αvintegrins, and sialic acid on target cells. Initial interactions of subgenus D adenoviruses with target cells have until now been poorly characterized. Here, we demonstrate that adenovirus type 8 (Ad8), Ad19a, and Ad37 use sialic acid as a functional cellular receptor, whereas the Ad9 and Ad19 prototypes do not.

Lifetime number of partners as the only independent risk factor for human papillomavirus infection: a population-based study

Background and Objectives. Previous studies of relationships between genital human papillomavirus infection and tentative risk factors have yielded conflicting results, possibly because of inaccuracy of the viral detection methods used and differences in selection criteria. Goal of This Study. To determine human papillomavirus prevalence and identify risk factors in a group of young Swedish women. Study Design. This was a population-based study involving comu-pletion of a structured questionnaire, analysis of cervical scrapings for human papillomavirus and Chlamydia trachomatis, and sero-logic tests for C. trachomatis and herpes simplex virus antibodies. Results. The prevalence of human papillomavirus infection was 22% among the sexually active women and 4% among the virgins. A number of factors were associated with human papillomavirus prevalence in univariate analysis, but logistic regression analysis showed that lifetime number of male sexual partners was the only independent risk factor for human papillomavirus infection (adjusted odds ratio, 7.45; 95 % CI, 2.79–19.92 for six or more partners vs. one partner). Conclusion. Human papillomavirus infection is a prevalent sexually transmitted disease among young Swedish women, and the lifetime number of male sexual partners is a major risk factor.

Sexual behaviour and papillomavirus exposure in cervical intraepithelial neoplasia: a population-based case-control study.

Sexual history is an established risk determinant for cervical neoplasia. It is not clear if human papillomavirus (HPV) exposure entirely explains the sexual behaviour-related risk or if other sexually transmitted agents may act as cofactors for HPV in carcinogenesis. The aim of this study was to elucidate whether HPV exposure or HPV persistence explains the sexual history-related risk of high-grade cervical intraepithelial neoplasia (CIN) using a population-based case-control study of most of the 254 women referred to colposcopy in the Vasterbotten county in Sweden because of an abnormal cervical smear during October 1993 to December 1995 and 320 age-matched women from the general population. The women were interviewed for sexual history and tested for presence of serum antibodies to HPV-16, -18 and -33 as well as for presence of HPV DNA in cervical brush samples. HPV-16, -18 and -33 seropositivity was specific for the corresponding type of HPV DNA, dependent on the lifetime sexual history and associated with a two- to threefold increased risk of CIN 3. There was no sexual history-related risk of CIN among HPV-seropositive women and adjustment for HPV DNA presence explained the sexual history-related risk of CIN. In conclusion, HPV exposure appeared to explain the sexual history-related risk of high-grade CIN.

Detection of human papillomavirus in cervical intra-epithelial neoplasia, using in situ hybridization and various polymerase chain reaction techniques

One hundred and forty-eight randomly chosen neutral-buffered formaldehyde-fixed cervical biopsies in which cervical intra-epithelial neoplasia (CIN) I–III had been diagnosed were tested for HPV (human papilloma virus) DNA by in situ hybridization (ISH) and polymerase chain reaction (PCR). For ISH, we utilized a biotinylated panprobe and type-specific, genomic probe sets. For PCR, we used the general primers GP5/GP6 and their recently described, elongated version GP5+/GP6+, and included the modification of hot-start PCR. Amplified DNA was detected by gel electrophoresis and slot blot hybridization. The positivity rate of ISH was 59% for all biopsies and 69%, 62% and 46% for CIN I, II and III, respectively. The sensitivity of GP5/GP6 was 74% with cold-start PCR and 78% with hot-start PCR. When GP5+/GP6+ was used, the sensitivity increased to 89% with cold-start PCR and to 95% with hot-start PCR. Based on the most sensitive PCR technique, HPV detection was 93%, 95% and 96% in CIN I, II and III, respectively. The number of HPV types decreased with the severity of the lesion, and HPV 16 was the predominant type. Multiple HPVs were rare and almost all HPV-positive cases could be typed. ISH and slot blot hybridization correlated well regarding HPV typing specificity. Our results confirm that distinct HPV types are present in a high proportion of cases of CIN. The sensitivity of ISH is lower than that of PCR. Furthermore, the modified general primers GP5+/GP6+ give a higher yield than GP5/GP6, while hot-start PCR increases sensitivity even further.

The influence of sexual and social factors on the risk of chlamydia trachomatis infections : a population-based serologic study

Background Genital chlamydia infections often are asymptomatic, which promotes their spread in the population. In women, the possible consequences of infection are pelvic inflammatory disease and infertility. Most studies on the prevalence of Chlamydia trachomatis have been based on clinical series, and prevalences tend to vary with the clinical setting. Few seroepidemiologic studies have emerged from industrialized countries. Goal of this Study To assess the prevalence of Chlamydia trachomatis using culture and serology, and its relationship with possible risk factors. Study Design This was a population-based study involving completion of a self-administered questionnaire, analysis of cervical samples for Chlamydia trachomatis, and serologic tests for Chlamydia trachomatis antibodies. Results The prevalence of Chlamydia trachomatis infection was 2.7 %, and the seroprevalence was 24.7 % among the sexually active women. Seropositivity was correlated with sexual behavior variables, and the incidence of serologic cross-reactivity with respiratory infections (strain TWAR) was low. Multivariate logistic regression analysis showed the number of sexual partners, age at first coitus, history of therapeutic abortion, and previous pelvic inflammatory disease to be independently correlated with seropositivity. Conclusion Early sexual experience and multiple lifetime sexual partners are independent risk factors for Chlamydia trachomatis infection.

The first human isolate of puumala virus in Scandinavia as cultured from phytohemagglutinin stimulated leucocytes

A virus isolate was recovered from blood leucocytes of a patient with nephropathia epidemica (NE). Leucocytes were isolated from EDTA‐blood by dextran sedimentation and cultured on monolayers of Vero E6 cells in the presence of phytohemagglutinin (PHA) in roller tubes during the first 72 hours of incubation followed by rolling culture for three weeks in total. Thereafter the first subculture was done in a plastic flask and afterward at at least 6 week intervals. Antigen was first detected after 6 months and 2 weeks of culture. When tested by monoclonal antibodies and patient sera the isolate had the characteristics of a PUU virus. PCR amplification using PUU‐specific primers and subsequent partial sequencing of the S and M segments revealed that the Umeå/305/human/95 virus differs from the Finnish PUU Sotkamo rodent prototype virus and is similar but not identical to rodent strains of PUU virus aquired from the same region as the patient isolate. It is we concluded that the first human isolate of the etiologic agent of NE in Scandinavia was recovered from blood leucocytes stimulated with PHA by long‐term culture in Vero E6 cells. The isolate belongs to the PUU serotype of hantaviruses as shown by its serologic profile and partial sequencing data. J. Med. Virol. 53:150–156, 1997.

Synthesis, Biological Evaluation, and Structure–Activity Relationships of 2-[2-(Benzoylamino)benzoylamino]benzoic Acid Analogues as Inhibitors of Adenovirus Replication

2-[2-Benzoylamino)benzoylamino]benzoic acid (1) was previously identified as a potent and nontoxic antiadenoviral compound (Antimicrob. Agents Chemother. 2010, 54, 3871). Here, the potency of 1 was improved over three generations of compounds. We found that the ortho, ortho substituent pattern and the presence of the carboxylic acid of 1 are favorable for this class of compounds and that the direction of the amide bonds (as in 1) is obligatory. Some variability in the N-terminal moiety was tolerated, but benzamides appear to be preferred. The substituents on the middle and C-terminal rings were varied, resulting in two potent inhibitors, 35g and 35j, with EC(50) = 0.6 μM and low cell toxicity.

Small-Molecule Screening Using a Whole-Cell Viral Replication Reporter Gene Assay Identifies 2-{[2-(Benzoylamino)Benzoyl]Amino}-Benzoic Acid as a Novel Antiadenoviral Compound

ABSTRACT Adenovirus infections are widespread in society and are occasionally associated with severe, but rarely with life-threatening, disease in otherwise healthy individuals. In contrast, adenovirus infections present a real threat to immunocompromised individuals and can result in disseminated and fatal disease. The number of patients undergoing immunosuppressive therapy for solid organ or hematopoietic stem cell transplantation is steadily increasing, as is the number of AIDS patients, and this makes the problem of adenovirus infections even more urgent to solve. There is no formally approved treatment of adenovirus infections today, and existing antiviral agents evaluated for their antiadenoviral effect give inconsistent results. We have developed a whole cell-based assay for high-throughput screening of potential antiadenoviral compounds. The assay is unique in that it is based on a replication-competent adenovirus type 11p green fluorescent protein (GFP)-expressing vector (RCAd11pGFP). This allows measurement of fluorescence changes as a direct result of RCAd11pGFP genome expression. Using this assay, we have screened 9,800 commercially available small organic compounds. Initially, we observed approximately 400 compounds that inhibited adenovirus expression in vitro by ≥80%, but only 24 were later confirmed as dose-dependent inhibitors of adenovirus. One compound in particular, 2-{[2-(benzoylamino)benzoyl]amino}-benzoic acid, turned out to be a potent inhibitor of adenovirus replication.

Viperin restricts Zika virus and tick-borne encephalitis virus replication by targeting NS3 for proteasomal degradation

ABSTRACT Flaviviruses are arthropod-borne viruses that constitute a major global health problem, with millions of human infections annually. Their pathogenesis ranges from mild illness to severe manifestations such as hemorrhagic fever and fatal encephalitis. Type I interferons (IFNs) are induced in response to viral infection and stimulate the expression of interferon-stimulated genes (ISGs), including that encoding viperin (virus-inhibitory protein, endoplasmic reticulum associated, IFN inducible), which shows antiviral activity against a broad spectrum of viruses, including several flaviviruses. Here we describe a novel antiviral mechanism employed by viperin against two prominent flaviviruses, tick-borne encephalitis virus (TBEV) and Zika virus (ZIKV). Viperin was found to interact and colocalize with the structural proteins premembrane (prM) and envelope (E) of TBEV, as well as with nonstructural (NS) proteins NS2A, NS2B, and NS3. Interestingly, viperin expression reduced the NS3 protein level, and the stability of the other interacting viral proteins, but only in the presence of NS3. We also found that although viperin interacted with NS3 of mosquito-borne flaviviruses (ZIKV, Japanese encephalitis virus, and yellow fever virus), only ZIKV was sensitive to the antiviral effect of viperin. This sensitivity correlated with viperins ability to induce proteasome-dependent degradation of NS3. ZIKV and TBEV replication was rescued completely when NS3 was overexpressed, suggesting that the viral NS3 is the specific target of viperin. In summary, we present here a novel antiviral mechanism of viperin that is selective for specific viruses in the genus Flavivirus, affording the possible availability of new drug targets that can be used for therapeutic intervention. IMPORTANCE Flaviviruses are a group of enveloped RNA viruses that cause severe diseases in humans and animals worldwide, but no antiviral treatment is yet available. Viperin, a host protein produced in response to infection, effectively restricts the replication of several flaviviruses, but the exact molecular mechanisms have not been elucidated. Here we have identified a novel mechanism employed by viperin to inhibit the replication of two flaviviruses: tick-borne encephalitis virus (TBEV) and Zika virus (ZIKV). Viperin induced selective degradation via the proteasome of TBEV and ZIKV nonstructural 3 (NS3) protein, which is involved in several steps of the viral life cycle. Furthermore, viperin also reduced the stability of several other viral proteins in a NS3-dependent manner, suggesting a central role of NS3 in viperins antiflavivirus activity. Taking the results together, our work shows important similarities and differences among the members of the genus Flavivirus and could lead to the possibility of therapeutic intervention.