Effect and mechanism of recombinant human fibroblast growth factor 18 on osteoporosis in OVX mice.

OBJECTIVES: This study aimed to investigate the effect and the mechanism of recombinant human fibroblast growth factor 18 (rhFGF18) on postmenopausal osteoporosis. METHODS: The effect of rhFGF18 on the proliferation and apoptosis of osteoblasts and the mechanism underlying such an effect was evaluated using an oxidative stress model of the MC3T3-E1 cell line. Furthermore, ovariectomy was performed on ICR mice to imitate estrogen-deficiency postmenopausal osteoporosis. Bone metabolism and bone morphological parameters in the ovariectomized (OVX) mice were evaluated. RESULTS: The results obtained from the cell model showed that FGF18 promoted MC3T3-E1 cell proliferation by activating the extracellular signal-regulated kinase (ERK) and p38 instead of c-Jun N-terminal kinase (JNK). FGF18 also prevented cells from damage inflicted by oxidative stress via inhibition of apoptosis. After FGF18 administration, the expression level of anti-apoptotic protein Bcl-2 in the mice was upregulated, whereas those of the pro-apoptotic proteins Bax and caspase-3 were downregulated. Administering FGF18 also improved bone metabolism and bone morphological parameters in OVX mice. CONCLUSIONS: FGF18 could effectively prevent bone loss in OVX mice by enhancing osteoblastogenesis and protecting osteoblasts from oxidative stress-induced apoptosis.

Identification of circulating biomarkers for differentiating patients with papillary thyroid cancers from benign thyroid tumors.

BACKGROUND: This study aimed to identify the potential circulating biomarkers of protein, mRNAs, and long non-coding RNAs (lncRNAs) to differentiate the papillary thyroid cancers from benign thyroid tumors. METHODS: The study population of 100 patients was classified into identification (10 patients with papillary thyroid cancers and 10 patients with benign thyroid tumors) and validation groups (45 patients with papillary thyroid cancers and 35 patients with benign thyroid tumors). The Sengenics Immunome Protein Array-combined data mining approach using the Open Targets Platform was used to identify the putative protein biomarkers, and their expression validated using the enzyme-linked immunosorbent assay. Next-generation sequencing by Illumina HiSeq was used for the detection of dysregulated mRNAs and lncRNAs. The website Timer v2.0 helped identify the putative mRNA biomarkers, which were significantly over-expressed in papillary thyroid cancers than in adjacent normal thyroid tissue. The mRNA and lncRNA biomarker expression was validated by a real-time polymerase chain reaction. RESULTS: Although putative protein and mRNA biomarkers have been identified, their serum expression could not be confirmed in the validation cohorts. In addition, seven lncRNAs (TCONS_00516490, TCONS_00336559, TCONS_00311568, TCONS_00321917, TCONS_00336522, TCONS_00282483, and TCONS_00494326) were identified and validated as significantly downregulated in patients with papillary thyroid cancers compared to those with benign thyroid tumors. These seven lncRNAs showed moderate accuracy based on the area under the curve (AUC = 0.736) of receiver operating characteristic in predicting the occurrence of papillary thyroid cancers. CONCLUSIONS: We identified seven downregulated circulating lncRNAs with the potential for predicting the occurrence of papillary thyroid cancers.

Anti-tumor immunity elicited by cross-linking vaccine heat shock protein 72 and alpha-fetoprotein epitope peptide.

Hepatocellular carcinoma (HCC) is one of the most common malignancies over the world. Alpha-fetoprotein (AFP) is an oncofetal protein during HCC development, which could generate weaker and less reproducible antitumor protection, and may serve as a target for immunotherapy. Therefore, it is imperative to enhance its immunogenicity and develop therapeutic vaccines to eliminate AFP-expressing tumors. In this study, by using glutaraldehyde cross-linking, we constructed a potential therapeutic peptide vaccine, heat shock protein 72 (HSP72) and AFP epitope peptide (HSP72/AFP-P). ELISPOT was applied to evaluate the quantity of AFP-specific CD8+ T cell that secreted IFN-γ in immunized BALB/C mice. Granzyme B released from natural killer cells and AFP-specific antibody responses in immunized mice were detected by ELISA. The anti-tumor effects were investigated by in vitro cytotoxic T-lymphocyte assays and in vivo tumor therapeutic experiments. The results showed that reconstructed HSP72 and AFP epitope peptide vaccine synergistically exhibited significant increases in AFP-specific CD8+ T cells, natural killer cells responses and impressive antitumor effects against AFP-expressing tumors. Immunization of BALB/C mice with HSP72/AFP-P vaccine elicited stronger T-cells responses. The numbers of IFN-γ-producing CD8+ T cells from mice immunized with HSP72/AFP-P were 30 times more than those from mice immunized with AFP-P, HSP72 or PBS (P < 0.01). The concentration of granzyme B in natural killer cells from mice immunized with HSP72/AFP-P were 15 times higher than that from other groups (P < 0.01). In vitro effector cells from mice immunized with HSP72/AFP-P showed much stronger cytolytic effect on H22 target cells than those from mice vaccinated with AFP-P, HSP72 or PBS (P < 0.01). Priming mice with the reconstructed vaccine exhibited robust strong protective immunity. Mice immunized with HSP72 or AFP-P alone demonstrated higher average tumor volumes than mice immunized with HSP72/AFP-P (P < 0.05). Our study suggests that constructing a tumor vaccine by cross-linking AFP antigen epitope peptide and HSP72 is a promising approach for cancer therapy.

Host genetic variants of ABCB1 and IL15 influence treatment outcome in paediatric acute lymphoblastic leukaemia.

BACKGROUND: Host germline variations and their potential prognostic importance is an emerging area of interest in paediatric ALL. METHODS: We investigated the associations between 20 germline variations and various clinical end points in 463 children with ALL. RESULTS: After adjusting for known prognostic factors, variants in two genes were found to be independently associated with poorer EFS: ABCB1 T/T at either 2677 (rs2032582) or 3435 (rs1045642) position (P=0.003) and IL15 67276493G/G (rs17015014; P=0.022). These variants showed a strong additive effect affecting outcome (P<0.001), whereby patients with both risk genotypes had the worst EFS (P=0.001), even after adjusting for MRD levels at the end of remission induction. The adverse effect of ABCB1 T/T genotypes was most pronounced in patients with favourable cytogenetics (P=0.011) while the IL15 67276493G/G genotype mainly affected patients without common chromosomal abnormalities (P=0.022). In both cytogenetic subgroups, increasing number of such risk genotypes still predicted worsening outcome (P<0.001 and=0.009, respectively). CONCLUSION: These results point to the prognostic importance of host genetic variants, although the specific mechanisms remain unclarified. Inclusion of ABCB1 and IL15 variants may help improve risk assignment strategies in paediatric ALL.

Sustainable Participation in Community Health Programs to Promote a Healthy Lifestyle and Prevent and Protect against Dementia among Rural Taiwanese Middle-Aged and Older Adults.

BACKGROUND: Resource and economic constraints limit access to health care in rural populations, and consequently, rates of chronic illnesses are higher in this population. Further, little is known about how rural populations adopt active and healthy lifestyle behavior for dementia prevention. OBJECTIVES: This study aimed to explore the impact of modification in lifestyle behaviors on changes in cognitive function among middle-aged and older adults living in a rural area of Taiwan. DESIGN: In this prospective longitudinal study, changes in lifestyle and cognitive function were compared between the experimental and control groups. SETTING: Six rural community care stations were randomly cluster sampled in southern Taiwan. PARTICIPANTS: A total of 155 participants were enrolled and classified into two groups according to their community activity participation rate (CAPR). The control group (n=68) had a CAPR < 1x/month, and the experimental group (n=87) had a CAPR ≥ 1x/month. MEASUREMENTS: Cognitive function of the participants was measured using the MMSE scale. Lifestyle behaviors were measured using a self-designed questionnaire based on the Transtheoretical Model. RESULTS: From 2018-2020, the experimental group successfully maintained a healthy lifestyle. The MMSE score in the experimental group was significantly higher in the 3rd year than that in the control group (25.37 vs 22.56, p < 0.001). CONCLUSIONS: Sustainable community participation and adopting a healthy lifestyle could effectively maintain the cognitive function of the study participants. However, more needs to be done to support rural older adults to maintain a healthy diet and control their weight.

Do all the patients with gastric parietal cell antibodies have pernicious anemia?

OBJECTIVE: This study evaluated whether all the patients with serum gastric parietal cell antibody (GPCA) positivity had pernicious anemia (PA). MATERIALS AND METHODS: The blood hemoglobin (Hb), iron, and vitamin B12 concentrations, and mean corpuscular volume (MCV) in 124 GPCA-positive patients were measured and compared with the corresponding data in 124 age- and sex-matched healthy controls. PA was defined by World Health Organization (WHO) as having an Hb concentration < 13 g dl(-1) for men and < 12 g dl(-1) for women, an MCV ≥ 100 fl, and a serum vitamin B12 level < 200 pg ml(-1) . RESULTS: We found that 20, 25, and 20 GPCA-positive patients had deficiencies of Hb (men < 13 g dl(-1) , women < 12 g dl(-1) ), iron (<60 µg dl(-1) ), and vitamin B12 (<200 pg ml(-1) ), respectively. Moreover, 16 GPCA-positive patients had abnormally high MCV (≥ 100 fl). GPCA-positive patients had a significantly higher frequency of Hb, iron, or vitamin B12 deficiency and of abnormally high MCV (all P-values < 0.001) than healthy controls. However, only 12.9% of 124 GPCA-positive patients were diagnosed as having PA by the WHO definition. CONCLUSION: Only 12.9% of GPCA-positive patients are discovered to have PA by the WHO definition.

Significant reduction of homocysteine level with multiple B vitamins in atrophic glossitis patients.

OBJECTIVE: This study evaluated whether supplementations of different vitamins and iron could reduce the serum homocysteine levels in 91 atrophic glossitis (AG) patients. MATERIALS AND METHODS: Atrophic glossitis (AG) patients with concomitant deficiencies of vitamin B12 only (n = 39, group I), folic acid only (n = 10, group II), iron only (n = 9, group III), or vitamin B12 plus iron (n = 19, group IV) were treated with vitamin BC capsules plus deficient hematinics. AG patients without definite hematinic deficiencies (n = 14, group V) were treated with vitamin BC capsules only. The blood homocysteine and hematinic levels at baseline and after treatment till all oral symptoms had disappeared were measured and compared by paired t-test. RESULTS: Supplementations with vitamin BC capsules plus corresponding deficient hematinics for groups I, II, III, IV patients and with vitamin BC capsules only for group V patients could reduce the high serum homocysteine levels to significantly lower levels after a mean treatment period of 8.3-11.6 months (all P-values < 0.05). CONCLUSION: Supplementations with vitamin BC capsules plus corresponding deficient hematinics or with vitamin BC capsules only can reduce the high serum homocysteine levels to significantly lower levels in AG patients.

Effects of an intervention on nutrition consultation for cancer patients.

We assessed whether cancer patients given a nutritional consultation by dietitians when discharged from the hospital experienced more health benefits than those not given a nutritional consultation. The McNemar test and the general linear model were used to examine the effect of nutrition intervention. A bubble chart was plotted to show the comparison between cancer groups. A total of 537 cancer patients discharged from a 1200-bed medical centre in Taiwan in 2011 were randomly divided into experimental and control groups. In the experimental group, nutritional status [evaluated using the Subjective Global Assessment (SGA) Classification technique], weight loss, and food intake recovery were significantly affected and returned to their usual levels, but in the control group, only food intake recovery was significantly affected. The effect of nutrition consultation intervention for cancer patients is thus evident. Significant positive effects were cancer-stage-dependent but not cancer-type-dependent. Future studies are recommended using the present study's methods to see whether the nutrition intervention effect occurs in cancer patients discharged from other hospitals throughout the world.

Analysis of Antarctic proteobacteria by PCR fingerprinting and screening for antimicrobial secondary metabolites.

Fifty-seven proteobacterium species were successfully isolated from soils of Barrientos Island of the Antarctic using 11 different isolation media. Analysis of 16S rDNA sequencing of these isolates showed that they belonged to eight different genera, namely Bradyrhizobium, Sphingomonas, Methylobacterium, Caulobacter, Paracoccus, Ralstonia, Rhizobium, and Staphylococcus. All isolates were studied for capability of producing antimicrobial and antifungal secondary metabolites using high-throughput screening models. Approximately 23 (13/57) and 2% (1/57) of isolates inhibited growth of Candida albicans ATCC 10231(T) and Staphylococcus aureus ATCC 51650(T), respectively. These results indicated that proteobacterium species isolates from Antarctic could serve as potential source of useful bioactive metabolites. Enterobacterial repetitive intergenic consensus (ERIC)-PCR fingerprinting produced nine clusters and 13 single isolates, with a high D value of 0.9248. RAPD fingerprinting produced six clusters and 13 single isolates, with a relatively low D value of 0.7776. ERIC-PCR analysis proved to have better discrimination capability than RAPD analysis and generated better clustering for all proteobacterium species isolates. We conclude that ERIC-PCR is a robust, reliable and rapid molecular typing method for discriminating different genera of proteobacteria.

Modulation of serum gastric parietal cell antibody level by levamisole and vitamin B12 in oral lichen planus.

OBJECTIVES: The objective of this study was to test the efficacy of three different treatment modalities on the reduction of serum anti-gastric parietal cell autoantibody (GPCA) level in GPCA-positive oral lichen planus (OLP) patients. MATERIALS AND METHODS: Of 147 GPCA-positive OLP patients, 100 were treated with levamisole plus vitamin B12, 10 with vitamin B12 only and 37 with levamisole only. The serum GPCA levels in 147 OLP patients were measured at baseline and after treatment. RESULTS: Treatment with levamisole plus vitamin B12 for a period of 2-50 months and treatment with vitamin B12 only for a period of 4-44 months could effectively reduce the high serum GPCA level to undetectable level in 100 and 10 OLP patients, respectively. However, treatment with levamisole only for a period of 2-50 months could not modulate the high mean serum GPCA titer to a significantly lower level in 37 OLP patients. A 92% GPCA recurrence rate was found in 25 OLP patients receiving no further vitamin B12 treatment during the GPCA-negative remission period. CONCLUSION: For GPCA-positive OLP patients, treatment modality containing vitamin B12 can effectively reduce the high serum GPCA level to undetectable level. OLP patients with underlying autoimmune atrophic gastritis trait should receive a maintenance vitamin B12 treatment for life.

Predicting New-Onset Diabetes Mellitus by Component Combinations of Premorbid Metabolic Syndrome among Older Adults in Taiwan.

Metabolic syndrome (MS) was conceptualized to identify people at risk for cardiovascular disease and type 2 diabetes; however, the epidemiology of MS and its combinations of components in older adults remains unclear. Data from the Senior Health Examination Program of the New Taipei City Government in Taiwan in 2014 were obtained for this study. All participants aged 65 years or older and those with a prior history of cardiovascular disease, cerebrovascular disease, or diabetes mellitus were excluded. 29,164 senior citizens were retrieved for this study, and 12,331 (41.28%) of the participants were male. Female participants were more likely to have MS (42.7% vs.31.3%, p <0.001). Female participants with MS were older than those without MS (73.15±6.5 vs. 72.10±6.14 years, p <0.001). Conversely, male participants with MS were younger than those without MS (72.93±6.70 vs. 73.52±6.98 years, p <0.001). The most common combination of MS components was the triad of high blood glucose, high blood pressure and central obesity (25.2% of all participants with MS). Age-related changes in MS component combinations were noted only when central obesity was present. The strongest MS component combination for new-onset diabetes mellitus was high blood glucose, hypertriglyceridemia, reduced HDL-C and central obesity (HR: 5.42, P<0.001). In conclusion, not all component combinations of MS were of the same prognostic impact or the risk for new-onset diabetes mellitus. Further study is needed to develop individualized intervention programs for MS based on risk profiles of older adults is needed.

Meiosis in Drosophila melanogaster. II. The prometaphase-I kinetochore microtubule bundle and kinetochore orientation in males.

Fourteen prometaphase kinetochore microtubule bundles have been examined in electron micrographs of serial sections. The majority (54%) of the microtubules extended from the polar region towards the kinetochore but do not end in the kinetochore proper. Rather, they stop short of the kinetochore (21%), graze the kinetochore (19%), or pass through the kinetochore (9%), displaying a free end distal to the pole. Other microtubules that make up the kinetochore bundle include: kinetochore-to-pole microtubules (24%), chromosome-to-pole microtubules (5%), pieces with two free ends (14%), and those microtubules with one end in the kinetochore and a free end distal to the kinetochore (9%). We conclude that the majority of the microtubules in the kinetochore bundle are most likely of polar origin rather than having been nucleated at the kinetochore. Prometaphase-I kinetochores can display any one of four patterns of microtubule connections with the poles, but the pattern of microtubule connections is not always correlated with kinetochore position. For instance, a kinetochore directly facing one pole may have microtubule connections with both poles while a kinetochore positioned 90 degrees to the spindle axis may have microtubules running towards one pole only.

Micromanipulated bivalents can trigger mini-spindle formation in Drosophila melanogaster spermatocyte cytoplasm.

Single (individual) bivalents in cultured Drosophila melanogaster primary spermatocytes were detached from the spindle with a micromanipulation needle and placed in the cytoplasm. Such bivalents are prevented from rejoining the spindle by a natural membrane barrier that surrounds the spindle, but they quickly orient as if on a spindle of their own and the half-bivalents separate in anaphase. Serial section electron microscopy shows that a mini-spindle forms around the cytoplasmic bivalent, i.e., the microtubule density in the vicinity of the bivalent is much greater than in other cytoplasmic regions. This microtubule population cannot be accounted for solely by kinetochore nucleation and/or capture of microtubules. Furthermore, the mini-spindles frequently form at odd angles to the main spindle, so that at least one pole has no relationship to the poles of the main spindle. We conclude that a bivalent, or factors that become associated with the bivalent as a result of the manipulation, can either stabilize microtubules or promote their assembly. The bivalent activates latent microtubule organizing centers, or alternatively, polar organizing material has been passively transported from the main spindle to the cytoplasm by the micromanipulation procedure.

Unrelated cord blood transplantation in children--a 10-year experience from UMMC.

Children who would benefit from a haematopoietic stem cell transplantation often lacked a compatible sibling donor. Unrelated cord blood transplantation was offered as an alternative donor source for patients with a variety of malignant and non-malignant diseases who had no further treatment options. Cord blood units were sourced from various international cord blood registries. The median nucleated and CD34+ cell doses were 8.7 x 10(7)/kg and 2.6 x 10(5)/kg respectively. In spite of adequate cell doses, a high rate of non-engraftment of 32% was observed. Acute graft-versus-host disease (GVHD) occurred in 14 out of the 15 patients who engrafted with 53% being grade III to IV GVHD. The five year disease free survival was 40.7% with infection and GVHD being the commonest causes of death. The five year disease free survival was 20.5% and 60.7% for malignant and non-malignant diseases respectively.

[The impacts of endoscopic sinus surgery with middle turbinate and superior turbinate resection on quality of life and olfactory function in patients with chronic rhinosinusitis with nasal polyps].

Objective:The aim of this study is to investigate the impacts of endoscopic sinus surgery(ESS) with middle turbinate and superior turbinate resection on quality of life and olfactory function in patients with chronic rhinosinusitis with nasal polyps(CRSwNP) and with dysosmia. Method:All of the 81 patients with CRSwNP and with dysosmia recieved ESS with middle turbinate and superior turbinate resection.The patients were given standardized drug treatments during the preoperative period,such as nasal irrigation,using local hormone spray,mucus decorporation agent by oral,using macrolide antibiotics according to the circumstances and so on.We used SNOT-20 to evaluate the quality of life preoperatively and postoperatively in patients;and used the T&T olfactory testing and VAS to evaluate the olfactory function of the patients.Result:The SNOT-20 test showed that "need to blow nose", "lack of a good sleep", "thick nasal discharge", "difficult to go to sleep",and "awkward" influence on the quality of life severely.The scores of all items showed decreasing tread in 2 weeks,1 month and 3 months after operation(P <0.05).Olfactory:Among the 81 patients(162 side),54 patients(108 sides) lost sense of smell completely in preoperative period and 27 patients' olfaction lost in varying degrees(10 patients are bilateral symmetry hyposmia and 17 patients are bilateral asymmetry hyposmia).Compared with the preoperative period,70 patients'(86.4%) olfactory function were improved at 3 months after the operation,in which 43 patients'(53.1%) olfactory function recovered to normal,and 27 patients'(33.3%) olfactory function improved in varying degrees;however,11 patients'(13.6%) olfactory function had not improvement at all.Sixty-one patients were followed up for more than one year.One year after operation,53 patients'(86.9%) olfactory function were improved,in which the 31 patients' (50.8%) olfactory function recovered to normal and 22 patients'(36.1%)olfactory function improved in varying degrees;8 patients'(13.1%) olfactory function had no improvement;the remaining 20 patients are being followed up.There was a significant difference between preoperative T&T olfactory testing and postoperative's(P <0.05);and so was VAS assessment(P <0.05). Conclusion: For the patients with CRSwNP and with dysosmia,the operation of ESS with middle turbinate and superior turbinate resection combined with standardized drug treatment in preoperative period can effectively improve the patients' quality of life and olfactory function.Hyperventilation and nasal dryness caused by excessive resection were not found.

Meiosis in Drosophila melanogaster, III. The effect of orientation disruptor (ord) on gonial mitotic and the meiotic divisions in males.

Orientation disruptor (ord), a meiotic mutant that is recombination defective in females and disjunction defective in males and females, has been analyzed using serial section electron and light microscopy. From analysis of primary spermatocytes we have confirmed that ord males are defective in some aspect of the mechanism(s) that holds sister chromatids together during meiosis. In addition, we have determined that ord causes high frequencies of nondisjunction during spermatogonial mitotic divisions, as well as during the meiotic divisions. Mitotic nondisjunction involves the large autosomes more frequently than the sex chromosomes or chromosome 4 and results in high frequencies of primary spermatocytes that are either monosomic or trisomic for chromosome 2 or 3. Abnormalities in spermatocyte cyst formation are also observed in males homozygous for ord. These abnormalities include loss of regulation of meiotic synchrony and the number of gonial cell divisions.

Secondary B-cell acute lymphoblastic leukemia following Wilms' tumor: clinical and in vitro chemosensitivity studies.

We report the clinical features and in vitro chemosensitivity assay findings of a 13-year-old girl who developed secondary B-cell acute lymphoblastic leukemia (ALL) 7 years after a diagnosis of Wilms' tumor. The patient was treated using the Berlin - Frankfurt - Muenster (BFM) ALL chemotherapy protocol with poor response to initial therapy before succumbing to sepsis. An in vitro chemosensitivity assay on her peripheral blood lymphoblasts was performed while she was undergoing induction therapy and showed a high level of resistance to drugs commonly used for ALL therapy, e.g. steroids, anthracyclines, vincristine and L-asparaginase. The mechanism of chemoresistance was not elicited, but was probably not related to P-glycoprotein (P-gp) over-expression. We believe that the in vitro chemosensitivity assay is a good indicator of cellular response to chemotherapy and may provide reliable information for the basis of the selection of drugs to be used for the treatment of similarly rare patients rather than relying on "standard" protocols.

Successful allogeneic bone marrow transplantation in severe chronic mucocutaneous candidiasis syndrome.

We report the successful HLA-identical sibling bone marrow transplantation (BMT) of a 12-year-old boy with chronic mucocutaneous candidiasis (CMC) syndrome who also had Coomb's positive haemolytic anaemia and recurrent bronchopneumonia with resulting bronchiectasis. Conditioning was with busulfan and cyclophosphamide. Engraftment was slow but complete. Selective red cell haemopoietic failure was encountered soon after transplantation but resolved spontaneously. The patient remains alive 3 years after transplantation and now has normal immune, haemopoeitic and pulmonary functions. No manifestation of CMC has been evident since transplantation.

Bone marrow transplantation in Malaysia.

The sole BMT centre in Malaysia caters only for children. Since 1987, 89 transplants have been performed using reverse barrier nursing techniques. The overall survival rate is 73% with the majority of survivors leading normal lives. The early and late infection rates of 46% and 13%, respectively, are comparable to those of other centres. Although the early septicaemia rate is 36% the immediate mortality rate is < 10%. GVHD is less frequent and severe and the interstitial pneumonitis rate lower than that in the West. The average cost of US $8000 per transplant is much lower than the cost of a transplant performed overseas. Thus we believe that our paediatric BMT programme is simple and cost-effective.

Characterization of a strain-specific monoclonal antibody to hepatitis delta virus antigen.

Sequences of the hepatitis delta virus (HDV) vary to different degrees among isolates. A monoclonal antibody, designated as HP6A1, against the antigen of HDV (HDAg) has been characterized for its specificity. HP6A1 bound to HDAg of isolate 25 (genotype I) that was used for immunization, but not to others of both genotypes I and II. The epitope recognized by HP6A1 was then determined by a phage library displaying various heptapeptides. A consensus peptide deduced has the best match with that of residues 4-10 of HDAg (isolate 25). To confirm the phage mapping result, Escherichia coli recombinant proteins containing different lengths and various segments of HDAg (isolate 25) were constructed. The shortest HDAg segment contained in the fusion protein that reacted with HP6A1 was residues 1-10. When this peptide was added to the N-terminus of a heterologous protein engineered for eucaryotic expression, the fusion protein was detected by HP6A1. It is concluded that HP6A1 recognizes an epitope located at the N-terminus of HDAg (isolate 25). Since viruses of quasi-species exist in natural infections, a question of how different viral strains interact in vivo remains to be explored. The highly specific MAb opens a possibility to examine the fate of one strain in the presence of other related species in a cell transfection system.