Search PubMed⌕ Search

Biomedical subjects

C Borel

Publications and source records attributed to C Borel.

At least 19 recordsLinked to original sources
PubMed2004

Comparative value of tumour grade, hormonal receptors, Ki-67, HER-2 and topoisomerase II alpha status as predictive markers in breast cancer patients treated with neoadjuvant anthracycline-based chemotherapy.

The aim of this study was to evaluate the predictive value of five different biological factors in breast cancer patients treated with neoadjuvant anthracycline-based chemotherapy: (1) tumour grade scored according to the Elston-Ellis classification, (2) hormonal receptor (HR) status; (3) tumour cell proliferation evaluated by Ki-67 staining, (4) HER-2 and topoisomerase II alpha (TopoIIalpha) expression evaluated by immunohistochemistry (IHC), (5) HER-2 and TopoIIalpha amplification evaluated by real-time polymerase chain reaction (PCR). 119 patients with operable breast cancer were treated with six cycles of FEC (100 5-fluorouracil (5-FU) 500 mg/m2, Epirubicin 100 mg/m2, Cyclophosphamide 500 mg/m2). Tumour response was assessed clinically and by computed tomography (CT) scan, then by pathological assessment. The clinical overall response (OR) was 80%, with 19% of complete responders (CR). The radiological OR was 71%, with 16% of CR. A pathological CR was demonstrated in 13% of the patients according to the Sataloff classification. In the multivariate analysis, the absence of HR expression and Ki-67 > or = 20% were predictive for a clinical CR. A high tumour grade was predictive for a pathological CR. Overexpression or amplification of HER2 or Topollcalpha were not predictive of response.

Adult↗
PubMed2003

Do genetic make-up and growth manipulation affect tomato fruit size by cell number, or cell size and DNA endoreduplication?

This work investigated the link between genetic and developmental controls of fruit size and composition. On two isogenic lines (CF12-C and CF14-L), differing by fruit weight and sugar content quantitative trait loci (QTLs) identified previously, basal and tip fruits were characterized at anthesis and at maturity through their growth, dry matter and sugar content, number and size of cells and nuclei DNA content. The influence of competition was assessed by removing either basal or tip ovaries at anthesis. On an intact inflorescence, CF12-C fruits grew less than CF14-L fruits, with 1.67 fewer cell layers and similar cell size, suggesting that genes controlling cell division may be responsible for this fruit size variation. Truss thinning masked the QTL effect on fruit size, mainly by reducing the difference in cell number between the two lines and by promoting cell expansion in tip fruits, so that fruit growth was similar at both positions and for both lines. Thus, in these lines, cell number exerts a control on final fruit size only when there is competition among fruits. Different responses of basal and tip fruits after flower removal suggested that this treatment induced changes in hormonal relationships within the truss. No fixed relationship between DNA endoreduplication and cell size was found, as while cell size and dry matter and sugar contents differed with tomato lines, fruit position and truss size, endoreduplication patterns were the same. CF12-C fruits had a higher dry matter (+0.3% of fresh weight) and carbohydrates (+8% of dry matter) content than CF14-L fruits. The percentage dry matter was independent of truss size but decreased slightly from basal to tip fruits.

Cell Count↗
PubMed2002

High-dose, single-agent irinotecan as first-line therapy in the treatment of metastatic colorectal cancer.

PURPOSE: The efficacy and safety of single-agent, high-dose irinotecan (CPT-11, Campto) 500 mg/m(2) every 3 weeks were investigated as first-line treatment for advanced colorectal cancer (CRC). PATIENTS AND METHODS: Patients were enrolled into the study to receive a first cycle of therapy with irinotecan at a dose of 350 mg/m(2) every 3 weeks, which could be escalated to 500 mg/m(2) for the second and subsequent cycles depending on toxicity. Efficacy, safety and pharmacokinetics were determined in the intent to treat (ITT) population and the high-dose population (i.e. patients who had received at least three cycles of irinotecan, the second and third at 500 mg/m(2)). RESULTS: Of 49 patients enrolled into the study (ITT population), 31 (63%) received at least three cycles of treatment with cycles 2 and 3 at an irinotecan dose of 500 mg/m(2) (the high-dose population). The response rates (RR) for the ITT and high-dose populations were 24.5% and 35.5%, respectively. The main grade 3/4 toxicities per cycle in the ITT and high-dose populations were neutropenia 22% and 17%, febrile neutropenia 5% and 3%, and diarrhoea 12% and 7%, respectively. The pharmacokinetics of irinotecan and its metabolite SN-38 were investigated in 31 patients in cycle 1 and 22 patients in cycle 2. Irinotecan clearance and SN-38 exposure were not sufficiently correlated with toxicity in cycle 1 to identify patients for dose increase in subsequent cycles. The exposure to irinotecan and SN-38 increased in proportion to dose from 350 to 500 mg/m(2). CONCLUSION: These results suggest that high-dose irinotecan can be safely administered as first-line monotherapy to approximately two-thirds of patients who present with advanced CRC following a selective first cycle.

Adenocarcinoma↗
PubMed2002

Multicentre phase II study of oxaliplatin as a single-agent in cisplatin/carboplatin +/- taxane-pretreated ovarian cancer patients.

BACKGROUND: This multicentre phase II open-label study evaluated safety and antitumour activity of oxaliplatin in cisplatin or carboplatin (cis/carboplatin) +/- taxane-pretreated advanced ovarian cancer (AOC) patients. PATIENTS AND METHODS: Forty-eight patients received oxaliplatin 130 mg/M2 intravenously every 3 weeks, 94% having a performance status (PS) 0-1. All were pretreated with cis/carboplatin and 21 (44%) with paclitaxel. The median number of involved organs was two, 18 (38%) had liver metastasis, 23 (48%) were platinum-resistant and 14 (29%) were taxane-resistant. Forty-two patients were evaluable for a response, 18 (43%) were platinum-resistant and 11 (26%) were taxane-resistant. RESULTS: A total of 253 cycles was administered (median: 5.5/patient). Median cumulative oxaliplatin dose was 666 mg/m2. National Cancer Institute-Common Toxicity Criteria toxicity analysis showed that seven patients (15%) had grade 3/4 thrombocytopenia, two patients (4%) had grade 3 neutropenia, and one patient had grade 3 anaemia. Eleven patients (23%) experienced grade 3 neurosensory toxicity. Of the 29 patients with peripheral neuropathy at the end of treatment, 55% had recovered or improved 1 month later. Eleven objective responses (two complete) were obtained in the 42 evaluable patients [ORR 26%, 95% confidence interval (CI) 14% to 42%], with 10/24 (42%, 95% CI 22% to 63%) in platinum-sensitive, and 1 of 18 (5.6%, 95% CI 0% to 27%) in platinum-resistant patients. Median response duration was 9.2 months (95% CI 6.6% to 11.8%), and median progression-free and overall survival in all treated patients were 4.3 months (95% CI 3.0% to 5.7%) and 15.0 months (95% CI 11.1% to 18.8%), respectively. CONCLUSION: Oxaliplatin has a good safety profile and is active in cis/carboplatin +/- paclitaxel-pretreated AOC patients.

Adult↗
PubMed2001

Molecular characterization of CLPT1, a SEC4-like Rab/GTPase of the phytopathogenic fungus Colletotrichum lindemuthianum which is regulated by the carbon source.

The gene CLPT1 (Colletotrichum lindemuthianum Protein Transport 1) encoding a Rab/GTPase was isolated from the filamentous fungus Colletotrichum lindemuthianum, the causal agent of bean anthracnose. At the amino acid level, CLPT1 shows between 54 and 80% identity to SEC4-like proteins, a class of molecules required for intracellular vesicular transport in yeasts. In particular, typical SEC4 domains involved in nucleotide binding and membrane attachment are present in the CLPT1 sequence. Functional identity of CLPT1 with SEC4 was confirmed by complementation of the Saccharomyces cerevisiae sec4-8 mutation. This is the first report of a gene involved in the control of intracellular vesicular trafficking in a phytopathogenic fungus. RNA blot analyses of CLPT1 expression were performed during in vitro growth of the fungus on synthetic media containing glucose or pectin, as single carbon source. The accumulation of CLPT1 mRNA was strongly increased on pectin, a plant cell wall polysaccharide that induces the production of extracellular pectinases, whereas the level of CLPT1 mRNA was below the detection threshold on glucose. These results suggest that CLPT1 is mainly involved in protein secretion and that the production of extracellular enzymes potentially involved in pathogenesis in filamentous fungi is sustained by induction of the genes involved in the secretory machinery.

Amino Acid Sequence↗
PubMed2001

Breast cancer occurred after treatment for Hodgkin's disease: analysis of 133 cases.

PURPOSE: To assess the clinical and histological characteristics of breast cancer (BC) occurring after Hodgkin's disease (HD) and give possible therapies and prevention methods. MATERIALS AND METHODS: In a retrospective multicentric analysis, 117 women and two men treated for HD subsequently developed 133 BCs. The median age at diagnosis of HD was 24 years. The HD stages were stage I in 25 cases (21%), stage II in 70 cases (59%), stage III in 13 cases (11%), stage IV in six cases (5%) and not specified in five cases (4%). Radiotherapy (RT) was used alone in 74 patients (63%) and combined modalities with chemotherapy (CT) was used in 43 patients (37%). RESULTS: BC occurred after a median interval of 16 years. TNM classification (UICC, 1978) showed 15 T0 (11.3%), 44 T1 (33.1%), 36 T2 (27.1%), nine T3 (6.7%), 15 T4 (11.3%) and 14 Tx (10.5%). Ductal infiltrating carcinoma and ductal carcinoma in situ (DCIS) represented 81.2 and 11.3% of the cases, respectively. Among the infiltrating carcinoma, the axillary involvement rate was 50%. Seventy-four tumours were treated by mastectomy without (67) or with (ten) RT. Forty-four tumours had lumpectomy without (12) or with (32) RT. Another four received RT alone, and one CT alone. Sixteen patients (12%) developed isolated local recurrence. Thirty-nine patients (31.7%) developed metastases and 34 died; 38 are in complete remission whereas five died of intercurrent disease. The 5-year disease-specific survival rate was 65.1%. The 5-year disease-specific survival rates for the pN0, pN1-3 and pN>3 groups were 91, 66 and 15%, respectively (P<0.0001), and 100, 88, and 64% for the TIS, T1 and T2. For the T3 and T4, the survival rates decreased sharply to 32 and 23%, respectively. These secondary BC are of two types: a large number of aggressive tumours with a very unfavourable prognosis (especially in the case of pN>3 and/or T3T4), and many tumours with a 'slow spreading' such as DCIS and microinvasive lesions. These lesions developed especially in patients treated exclusively by RT. CONCLUSIONS: The young women and girls treated for HD should be carefully monitored in the long-term by clinical examination, mammography and ultrasonography. We suggest that a baseline mammography is performed 5-8 years after supradiaphragmatic irradiation (complete mantle or involved field) in patients who were treated before 30 years of age. Subsequent mammographies should be performed every 2 years or each year, depending on the characteristics of the breast tissue (e.g. density) and especially in the case of an association with other BC risk factors. This screening seems of importance due to excellent prognosis in our T(1S)T(1) groups, and the possibility of offering these young women a conservative treatment.

Adolescent↗
PubMed2001

Carcinoma of an unknown primary site: a chemotherapy strategy based on histological differentiation--results of a prospective study.

BACKGROUND: To evaluate the efficacy and toxicity of a chemotherapy strategy based on histological differentiation, for patients with carcinoma of unknown primary site. PATIENTS AND METHODS: Forty-eight patients were prospectively included in the trial. Thirty patients with poorly-differentiated carcinoma or poorly-differentiated adenocarcinoma (group A) received a combination of cisplatin and etoposide. Patients with a responsive or stable disease after two cycles received the same regimen plus bleomycin, ifosfamide and G-CSF. Eighteen patients with well- or moderately-differentiated carcinoma (group B) received cisplatin, continuous infusion 5-fluorouracil (5-FU) and alpha-interferon. Treatment was maintained in case of response or stable disease for up to six cycles. RESULTS: The overall response rate (RR) for the entire group is 43% (95% confidence interval (CI): 35.9%-50.1%): seven CR and five PR in group A (RR = 40%) and six CR and two PR in group B (RR = 44%). Grade 4 leucopenia was observed in 22 (46%) patients and sepsis in 3 (6%). Median survival is 9.4 months (range 5-13.7 months) and 16.1 months (range 11.8 20.3 months), respectively. CONCLUSIONS: This chemotherapy strategy is one way to achieve high response rates, particularly for patients with well- or moderately-differentiated adenocarcinoma usually considered poorly chemosensitive.

Adenocarcinoma↗
PubMed2001

Systematic esophageal endoscopy screening in patients previously treated for head and neck squamous-cell carcinoma.

BACKGROUND: An attempt was made to improve metachronous oesophageal cancer prognosis through bi-annual systematic esophageal endoscopy screening in patients treated for head and neck cancer. PATIENTS AND METHODS: Bi-annual esophageal endoscopy, without a staining procedure, was performed in 1560 patients from 1987 to 1997. The distribution of previous head and neck cancer was oral cavity (20%), oropharynx (30%), hypopharynx (34%), and larynx (16%). All patients had initial panendoscopic inspection before HNSCC treatment. Esophageal tumors were considered to be second synchronous primaries when discovered within the first six months of initial tumor diagnosis. RESULTS: Fifty metachronous esophageal asymptomatic cancers (42 T1 and 7 in situ carcinomas) were diagnosed by endoscopy. The median time between the HNC and the esophageal carcinoma was 43 months (7-137 months). Metachronous esophageal carcinoma was discovered in 2.6% of patients with oral cavity tumor, 5.7% of patients with oropharynx tumor, 2.3% of patients with hypopharynx tumor, and 1.7% of patients with larynx tumor. Causes of death were: 41.1% related to esophageal tumor with tumor progression, metastatic evolution, or treatment toxicity; 28.9% related to non malignant causes; 26.6% related to a cancer that was not of esophageal origin. CONCLUSIONS: Over a 10-year period, systematic bi-annual esophageal endoscopy uncovered metachronous esophageal tumors in 3.2% of 1560 patients originally treated for head and neck carcinoma, developing in a median time of 47 months. Patients with initial oropharyngeal tumors had a significantly higher risk of metachronous esophageal SCC, compared to the other tumor sites (P < 0.02 with Fisher exact test). Given the elevated death rate not related to the esophageal cancer and the median survival of 16 months, any potential benefit from this time-consuming procedure is debatable.

Adult↗
PubMed2001

Initial amplification of duck hepatitis B virus covalently closed circular DNA after in vitro infection of embryonic duck hepatocytes is increased by cell cycle progression.

The relationship between the cell cycle and early amplification of duck hepatitis B virus covalently closed circular (CCC) DNA was studied after in vitro infection of fetal hepatocytes. We first showed that embryonic hepatocytes proliferated for at least 6 days after plating and that complete viral replication including CCC DNA amplification occurred in these proliferating cells. Addition of sodium butyrate or aphidicolin reversibly blocked cells in the G1 phase and diminished CCC DNA synthesis, which was restored after drug withdrawal, concomitantly with the entry of cells into S phase. Cell cycle progression of fetal hepatocytes can be triggered by stimulation with epidermal growth factor (EGF), hepatocyte growth factor (HGF), and tumor growth factor alpha (TGF-alpha). CCC DNA synthesis increased with progression to the S phase induced by EGF, HGF, and TGF-alpha alone or in combination. By contrast, tumor growth factor beta (TGF-beta) alone or in combination with EGF inhibited cell proliferation and viral DNA synthesis. By double labeling, viral nucleocapsids were found predominantly in bromodeoxyuridine-positive hepatocytes, indicating that high viral replication occurs preferentially in proliferating hepatocytes. CCC DNA was also detected mainly in cells in the S and G2/M phases separated from cells in the G1 phase by cell sorting. Taken together, these results show that hepatocyte proliferation may positively regulate the initial amplification of CCC DNA of avian hepadnaviruses, and may explain why mitosis is not necessarily associated with loss of CCC DNA.

Animals↗
PubMed2001

N. plumbaginifolia zeaxanthin epoxidase transgenic lines have unaltered baseline ABA accumulations in roots and xylem sap, but contrasting sensitivities of ABA accumulation to water deficit.

A series of transgenic lines of Nicotiana plumbaginifolia with modified expression of zeaxanthin epoxidase gene (ZEP) provided contrasting ABA accumulation in roots and xylem sap. For mild water stress, concentration of ABA in the xylem sap ([ABA](xylem)) was clearly lower in plants underexpressing ZEP mRNA (complemented mutants and antisense transgenic lines) than in wild-type. In well-watered conditions, all lines presented similar [ABA](xylem) and similar ABA accumulation rates in detached roots. Plants could, therefore, be grown under normal light intensities and evaporative demand. Both ZEP mRNA abundance and ABA accumulation rate in roots increased with water deficit in all transgenic lines, except in complemented aba2-s1 mutants in which the ZEP gene was controlled by a constitutive promoter which does not respond to water deficit. These lines presented no change in root ABA content either with time or dehydration. The increase in ZEP mRNA abundance in roots with decreasing RWC was more pronounced in detached roots than in whole plants, suggesting a difference in mechanism. In all transgenic lines, a linear relationship was observed between predawn leaf water potential and [ABA](xylem), which could be reproduced in several experiments in the greenhouse and in the growth chamber. It is therefore possible to represent the effect of the transformation by a single parameter, thereby allowing the use of a quantitative approach to assist understanding of the behaviour of transgenic lines.

Abscisic Acid↗
PubMed2001

Chemotherapy response of breast cancer depends on HER-2 status and anthracycline dose intensity in the neoadjuvant setting.

We evaluated the predictive value of a tumor's HER-2 status for chemotherapy response in the neoadjuvant setting and the effect of anthracycline dose intensity on this predictive value. HER-2 status was evaluated by immunochemistry on microbiopsy before neoadjuvant chemotherapy (monoclonal antibody CB-11; Novocastra) in 39 patients (group A) treated with FEC50 (500 mg/m(2) 5-fluorouracil, 50 mg/m(2) epirubicin, and 500 mg/m(2) cyclophosphamide) and 40 patients (group B) treated with FEC100 (500 mg/m(2) 5-fluorouracil, 100 mg/m(2) epirubicin, and 500 mg/m(2) cyclophosphamide). All tumors were stage II or noninflammatory stage III adenocarcinoma. Overall response rate (OR) was evaluated through ultrasound and mammographic measurements. Pathological complete response was evaluated by tumor excision and axillary node resection after six cycles of chemotherapy. Patient and tumor characteristics (age, tumor size, clinical nodal status, SBR grade, hormonal receptor status, and HER-2 expression) were similar in the two groups. In univariate analyses, anthracycline dose was the only factor predictive of response (OR = 61.5% with FEC50; OR = 82.5% with FEC100; P = 0.038). When anthracycline dose was correlated with HER-2 status, an OR of 73.9% was demonstrated in HER-2- tumors (tumors without HER-2 overexpression), and an OR of 12.5% was demonstrated in HER-2+ tumors (tumors with HER-2 with overexpression) in group A. In group B, an OR of 69.5% was demonstrated in HER-2- tumors, and an OR of 100% was demonstrated in HER-2+ tumors. There was no difference in OR for HER-2- tumors treated with FEC50 or FEC100 (P = 0.74). On the other hand, erbB-2+ tumors treated with FEC100 had a significantly better OR than HER-2+ tumors treated with FEC50 (P = 0.0003). In a multivariate analysis, the most powerful predictive factor of OR was a conditional variable associating anthracycline dose with HER-2 status. Low-dose anthracycline and HER-2+ predicted a poor OR, low- or high-dose anthracycline and HER-2- predicted an intermediate OR, and high-dose anthracycline and HER-2+ predicted a high OR. Our results merit additional studies, given the possibility for choosing anthracycline dose according to a tumor's HER-2 status.

Adenocarcinoma↗
PubMed2000

HIV-1 Nef protein binds to the cellular protein PACS-1 to downregulate class I major histocompatibility complexes.

Major-histocompatibility-complex (MHC) proteins are used to display, on the surface of a cell, peptides derived from foreign material - such as a virus - that is infecting that cell. Cytotoxic T lymphocytes then recognize and kill the infected cell. The HIV-1 Nef protein downregulates the cell-surface expression of class I MHC proteins, and probably thereby promotes immune evasion by HIV-1. In the presence of Nef, class I MHC molecules are relocalized from the cell surface to the trans-Golgi network (TGN) through as-yet-unknown mechanisms. Here we show that Nef-induced downregulation of MHC-I expression and MHC-I targeting to the TGN require the binding of Nef to PACS-1, a molecule that controls the TGN localization of the cellular protein furin. This interaction is dependent on Nef's cluster of acidic amino acids. A chimaeric integral membrane protein containing Nef as its cytoplasmic domain localizes to the TGN after internalization, in an acidic-cluster- and PACS-1-dependent manner. These results support a model in which Nef relocalizes MHC-I by acting as a connector between MHC-I's cytoplasmic tail and the PACS-1-dependent protein-sorting pathway.

Animals↗
PubMed2000

Neuroendocrine small cell carcinoma of the uterine cervix: what disease? What treatment? Report of ten cases and a review of the literature.

Neuroendocrine small cell carcinoma of the uterine cervix (NESCCC) is an entity with very aggressive behaviour. The optimal initial therapeutic approach to this rare disease has not yet been clearly defined. We reviewed our experience of this disease over the past 10 years with regard to chemosensitivity. Since 1988, ten patients (mean age 33 years; range 24-47) have been diagnosed with NESCCC and treated in our institutions. Disease stage at presentation was IA (one), IB (five, two with lymph node involvement), IIB (one), IIIB (one), and IV (two). One patient had metastatic disease at presentation; three developed metastases during initial treatment. Eight patients underwent surgery and eight received radiation therapy. Six patients received pre- or postoperative cisplatinumvepeside (PE) combination chemotherapy, either alone or concurrently with radiation therapy. PE alone as primary chemotherapy led to disease stabilization in the two patients so treated; concurrent PE and radiation therapy resulted in a pathological complete response in one patient. Eight patients relapsed within 16 months and died of their disease within 29 months from the initial diagnosis. Two patients are alive with no evidence of disease at 13 and 53 months. Our series confirms the previously described very poor prognosis of NESCCC, despite initial aggressive multidisciplinary treatment. It may be that the introduction of chemotherapy, especially combined primary chemoradiotherapy, might allow patients to do a little better, although at the moment there is no good evidence one way or the other.

Adult↗
PubMed1999

Enhanced duck hepatitis B virus gene expression following aflatoxin B1 exposure.

Epidemiological studies have suggested synergistic interactions between chronic hepatitis B virus (HBV) infection and aflatoxin B1 (AFB1) exposure in the etiology of hepatocellular carcinoma (HCC), although the molecular mechanisms of their interactions are still not understood. The aim of this study was to use the Pekin duck model to investigate the impact of AFB1 exposure on duck hepatitis B virus (DHBV) replication during the early stages of virus-carcinogen interactions. Six-week-old chronic DHBV-carrier or uninfected ducks were exposed to AFB1 for 5 weeks or treated with dimethylsulfoxide (DMSO) as a control. Animals were observed for 6 to 13 weeks after AFB1 treatment to study the influence of AFB1 exposure on DHBV replication and liver pathologies. Histological analysis showed more marked changes in the livers of AFB1-treated ducks, and these were enhanced by DHBV infection. A significant increase in serum and liver DHBV DNA level was observed in AFB1-treated ducks as compared with DMSO-treated controls. In addition, viral RNAs, in particular the pregenomic RNA that is the template of viral replication, and intrahepatic DHBV DNA replicative intermediates, were significantly increased by AFB1 treatment. Moreover, an overexpression and accumulation of DHBV large envelope (L) protein was observed in the hepatocytes of AFB1-exposed animals. The in vitro study has further confirmed an increase in intracellular viral DNA and in virus release in AFB1-treated primary duck hepatocytes. Taken together, our results indicate that AFB1 exposure leads to an increase in virus gene expression associated with intrahepatic accumulation of DHBV L protein and enhanced liver pathology.

Aflatoxin B1↗
PubMed1999

The SATE pronucleotide approach applied to acyclovir: part II. Effects of bis(SATE)phosphotriester derivatives of acyclovir on duck hepatitis B virus replication in vitro and in vivo.

The in vitro and in vivo antiviral activities of two mononucleoside phosphotriester derivatives of acyclovir (ACV) incorporating S-acyl-2-thioethyl (SATE) groups are reported using the duck model of hepatitis B (DHBV). In primary duck hepatocyte cultures, the described phosphotriesters significantly inhibited the replication of DHBV at submicromolar concentrations. They were found to be more potent than the parent nucleoside. This result was in agreement with our data concerning the anti-HBV activity of these pronucleotides in HepG2.2.15 cells (previous paper). In vivo, the studied SATE pronucleotide was also found to be more efficient than ACV in infected ducklings upon short-term oral therapy, while intraperitoneal treatment showed high anti-DHBV activity with both ACV and its SATE pronucleotide in this animal model. These findings demonstrate the potential of SATE pronucleotides of ACV as anti-HBV agents.

Acyclovir↗
PubMed1999

Residues critical for duck hepatitis B virus neutralization are involved in host cell interaction.

To date, no detailed analysis of the neutralization properties of duck hepatitis B virus (DHBV) has been reported, and it is not clear whether any of the known neutralization epitopes correspond to the viral receptor binding site or to sequences involved in the cell entry pathway. We demonstrate here that antibodies directed against two overlapping peptides (amino acids 83 to 97 and 93 to 107), covering the sequences of most DHBV pre-S neutralizing epitopes, both inhibit virus binding to primary duck hepatocytes and neutralize virus infectivity. An extensive mutagenesis of the motif 88WTP90, which is the shortest sequence of the epitope recognized by the virus-neutralizing monoclonal antibody (MAb) 900 was performed in order to define the amino acids involved in these interactions. Single point mutations within this epitope affected neither virus replication nor infectivity but abolished virus neutralization by MAb 900 completely. Interestingly, mutants with two and three consecutive residue replacements (SIP and SIH) within this epitope retained replication competence but were no longer infectious. The loss of infectivity of SIH and SIP mutant particles was associated with significantly reduced binding to primary duck hepatocytes and could be rescued by trans complementation with wild-type pre-S protein. Taken together, these results indicate that each amino acid of the DHBV pre-S sequence 88WTP90 is critical for recognition by the neutralizing MAb 900 and that replacement of the first two or all three residues strongly reduces virus interaction with hepatocytes and abrogates infectivity. These data imply that the motif 88WTP90 contains key residues which are critical for interaction with both the neutralizing MAb and the host cell.

Animals↗
PubMed1998

Phosphorylation of DHBV pre-S: identification of the major site of phosphorylation and effects of mutations on the virus life cycle.

Four potential serine/threonine phosphorylation sites [(S/T)-P motif], designated P1-P4, on the pre-S protein of duck hepatitis B virus (DHBV) have been mutated. Mutants include single (P2, P3, P4) and double amino acid substitutions (P1 + P2, P3 + P4) and one with all four sites mutated (4P). Serine at position 118 (P3) was identified as the major site of phosphorylation by Western blotting and radioimmunoprecipitation after in vitro cell labeling with [35S]methionine or [33P]orthophosphate. Mutant virions generated by transfection of LMH cells were infectious both in vitro in duck hepatocyte primary cultures and in vivo in Pekin ducks. Intracellular relaxed circular (RC) and covalently closed circular (ccc) DNA syntheses were not affected by the P3 mutation or even the quadruple mutant. Extracellular virus production was slightly increased when the P3 site was mutated. CsCl gradient centrifugation showed no clear difference between mutant and wild-type virus with respect to the ratios of enveloped virus and nucleocapsid particles in hepatocyte culture supernatants. Trypsin or V8 protease digestion with or without NP-40 indicated that phosphorylation of the pre-S domain is not involved in determining the transmembrane topology of DHBV large protein. This phenotypic analysis indicates that DHBV pre-S phosphorylation has no apparent effect on DHBV replication and formation of mature viral particles in duck hepatocyte primary culture and does not affect infectivity in ducklings.

Amino Acid Sequence↗