Construction of an oral recombinant DNA vaccine from H pylori neutrophil activating protein and its immunogenicity

AIM: To construct a live attenuated Salmonella typhimurium (S. typhimurium) strain harboring the H pylori neutrophil activating protein (HP-NAP) gene as an oral recombinant DNA vaccine, and to evaluate its immunogenicity.

METHODS: By genetic engineering methods, the genomic DNA of H pylori was extracted as a template. The total length of the HP-NAP gene was amplified by polymerase chain reaction (PCR) and cloned into pBT vector for sequencing and BLAST analysis, then subcloned into a eukaryotic expression vector pIRES followed by PCR identification and restriction enzyme digestion. The identified recombinant plasmid pIRES-NAP was transfected into COS-7 cells for target fusion protein expression, and its antigenicity was detected by Western blotting. Then the recombinant plasmid was transformed into a live attenuated S. typhimurium strain SL7207 as an oral vaccine strain, and its immunogenicity was evaluated with animal experiments.

RESULTS: A 435 bp product was cloned using high homology with HP-NAP gene in GenBank (more than 98%). With identification by PCR and restriction enzyme digestion, a recombinant eukaryotic expression plasmid pIRES-NAP containing the HP-NAP gene of H pylori was successfully constructed. The expressed target protein had a specific reaction with H pylorii whole cell antibody and showed a single strip result detected by Western blotting. Oral immunization of mice with recombinant DNA vaccine strain SL7207 (pIRES-NAP) also induced a specific immune response.

CONCLUSION: The successful construction of HP-NAP oral DNA vaccine with good immunogenicity may help to further investigate its immunoprotection effects and develop vaccine against H pylori infection.

Effects of recombinant human canstatin protein in the treatment of pancreatic cancer

AIM: To examine the effect of canstatin, a newly discovered endogenous inhibitor of angiogenesis, in the treatment of pancreatic cancer in vivo.

METHODS: The canstatin cDNA fragment was synthesized and amplified from the total RNA extracted from human placenta tissues by RT-PCR. The resulting product was firstly cloned into pUCm-T vector, then into plasmid pET-22b (+) and transformed into E. coli BL21. Isopropyl-1-thio-b-Dgalactopyran-oside (IPTG) was used to induce the expression of canstatin protein and affinity chromatography was used to purify the protein. To determine the activity of purified recombinant human canstatin (rhCanstatin), orthotopic xenograft human pancreatic cancer models were established. Human pancreatic cancer cells (SW1990) were injected into the pancreas of BALB/c nude mice. Twenty-four nude mice with orthotopic xenograft tumor were randomly divided into 3 groups 10 d after the inoculation, and were treated with PBS 0.3 mL, or canstatin 5 mg/kg, or 10 mg/kg per day for 3 wk intraperitoneally. When the experiment was over, all tumors were resected and the effects of rhCanstatin on tumor growth, microvessel density (MVD) were analyzed.

RESULTS: After IPTG induction, SDS-PAGE showed a new monomeric 24 kDa protein band. This protein was purified through affinity chromatography and refolded through dialysis with a final concentration of 60 mg/L. In orthotopic pancreatic cancer models, the final tumor volume in groups treated with PBS, canstatin 5 mg/kg, 10 mg/kg were 355.21 ± 39.54 mm³, 112.73 ± 10.47 mm³, and 61.75 ± 6.99 mm³ respectively. The immunohistochemical examination showed that the MVD in tumors treated with canstatin was significantly less than that in other group.

CONCLUSION: These findings demonstrate that the rhCanstatin effectively retards the growth of pancreatic cancer in a dose-dependent manner through inhibiting angiogenesis and may be a promising therapeutic agent for pancreatic cancer treatment in the clinic.

Chemokine gene expression in pancreatic tissue and effects of oxymatrine in early acute necrotizing pancreatitis

AIM: To investigate the expression of cytokine-induced neutrophil chemoattractant (CINC) and monocyte chemoattractant protein-1/JE (MCP-1/JE) genes in the pancreas, and to assess the influence of Chinese herb extraction oxymatrine (Oxy) on the expression of CINC and MCP-1/JE genes and the therapeutic effects in early acute necrotizing pancreatitis (ANP).

METHODS: ANP was induced by retrograde infusion of 50 g/L sodium taurocholate into the biliary pancreatic duct of rats. Fifty-six rats were randomly divided into three groups: sham operation (SO) group, ANP 3 h, 6 h, 12 h groups, and Oxy 3 h, 6 h, 12 h groups. The activity of serum amylase (Amy), the serum levels of glutamic-pyruvic transaminase (ALT) and creatinine (Cr) were determined. Pathological changes of the pancreas were observed. The expression of CINC and MCP-1/JE genes in the pancreas was assayed.

RESULTS: Compared with that in SO group, the expression of CINC and MCP-1/JE genes in the pancreas in ANP groups were all increased greatly (0.61 ± 0.08, 0.76 ± 0.10, 0.89 ± 0.12, 0.42 ± 0.06, 0.65 ± 0.08, 0.94 ± 0.12, P < 0.01). Following the induction of ANP, the expression of CINC and MCP-1/JE genes was both up-regulated, which was significantly correlated with the pathological changes of the pancreas (r = 0.89 and 0.82, respectively, P < 0.05). Oxy attenuated the increase of CINC and MCP-1/JE gene expression (0.34 ± 0.05, 0.45 ± 0.06, 0.51 ± 0.06 vs 0.31 ± 0.04, 0.34 ± 0.04, 0.36 ± 0.05, in ANP 3 h, 6 h, 12 h groups and Oxy 3 h, 6 h, 12 h groups, respectively P < 0.01). Serum Amy, ALT and Cr levels were reduced, (Amy: 25.391.93 mkat, 37.66 ± 4.27 μkat, 96.00 ± 9.19 μkat; ALT: 94.5 ± 58.3 nkat/L, 283.8 ± 115.5 nkat/L, 469.7 ± 157.3 nkat/L; Cr: 81.4 ± 17.7 μmol/L, 89.1 ± 18.7 μmol/L, 110.7 ± 12.8 μmol/L, P < 0.05 or P < 0.01), and the pathological changes of pancreas were ameliorated by Oxy.

CONCLUSION: CINC and MCP-1/JE might play important roles in early ANP. The expression of CINC and MCP-1/JE gene in the pancreas can be inhibited by Oxy. Oxy therapy was effective in experimental ANP.

p38 mitogen-activated protein kinase signal transduction pathway in pathogenesis of severe acute pancreatitis in rats

AIM: To study the dynamic changes of p38 mitogen-activated protein kinase (p38 MAPK) phosphorylation and to assess the effect of p38 MAPK phosphorylation inhibitor in severe acute pancreatitis (SAP) in rats.

METHODS: The SAP model was induced by bili-pancreatic duct retrograde infusion with 5% sterile sodium taurocholate solution. Eighty Sprague-Dawley (SD) rats were randomly divided into sham-operation (SO) group (n = 30), SAP-NS group (n = 25) and SAP-CNI1493 group (n = 25). In the SAP-CNI1493 group, SD rats were administered with 10 mg/kg inhibitor CNI-1493 (i. v.) 30 min before induction of SAP. In SAP-NS group, rats received same volume isotonic saline (i. v.) as CNI-1493. Pancreatic tissues and serum samples were collected before and 15 min, 0.5 h, 1 h, 3 h, 6 h after operation. Western blot analysis was performed to determine the phosphorylations of p38 MAPK in the pancreas homogenates. Serum levels of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) were measured by ELISA; Pathological changes of pancreas were examined and scored with light microscopy.

RESULTS: In the SO group, basal p38 MAPK phosphorylation was detected. In the SAP-NS group, the p38 MAPK phosphorylation in the pancreas homogenates reached the maximum at 15 min, remained at a similar level at 30, 60 and 180 min, and declined to the same level as that in SO group at 6 h. In the SAP-NS group and SAP-CNI1493 group, the densities of the band detected by Western blot were 5 200±360, 3 500±250 at 15 min, and 4 910±320, 2 500340 at 30 min (P <0.01). In SAP-CNI1493 group, the serum levels of IL-1β and TNF-α were decreased significantly as compared with those in SAP-NS group (P <0.01). The severity of tissue damage in the SAP-CNI1493 group at 3 h were significantly attenuated in comparison with that of the SAP-NS group (P<0.01).

CONCLUSION: The p38 MAPK plays an important role in the pathogenesis of SAP. Inhibition of p38 MAPK phosphorylation may be a potential approach for prevention and treatment of SAP.

Construction of a recombinant attenuated Salmonella typhimurium DNA vaccine carrying Helicobacter pylori hpaA

AIM: To construct a recombinant attenuated Salmonella typhimurium DNA vaccine carrying Helicobacter pylori hpaA gene and to detect its immunogenicity.

METHODS: Genomic DNA of the standard H pylori strain 17 874 was isolated as the template, hpaA gene fragment was amplified by polymerase chain reaction (PCR) and cloned into pUCmT vector. DNA sequence of the amplified hpaA gene was assayed, then cloned into the eukaryotic expression vector pIRES through enzyme digestion and ligation reactions. The recombinant plasmid was used to transform competent Escherichia coli DH5α, and the positive clones were screened by PCR and restriction enzyme digestion. Then, the recombinant pIRES-hpaA was used to transform LB5000 and the recombinant plasmid isolated from LB5000 was finally used to transform SL7207. After that, the recombinant strain was grown in vitro repeatedly. In order to identify the immunogenicity of the vaccine in vitro, the recombinant pIRES-hpaA was transfected to COS-7 cells using LipofectamineTM2000, the immunogenicity of expressed HpaA protein was detected with SDS-PAGE and Western blot.

RESULTS: The 750-base pair hpaA gene fragment was amplified from the genomic DNA and was consistent with the sequence of H pylori hpaA by sequence analysis. It was confirmed by PCR and restriction enzyme digestion that H pylori hpaA gene was inserted into the eukaryotic expression vector pIRES and a stable recombinant live attenuated Salmonella typhimurium DNA vaccine carrying H pylori hpaA gene was successfully constructed and the specific strip of HpaA expressed by pIRES-hpaA was detected through Western blot.

CONCLUSION: The recombinant attenuated Salmonella typhimurium DNA vaccine strain expressing HpaA protein with immunogenicity can be constructed and it may be helpful for further investigating the immune action of DNA vaccine in vivo.

Role of nucleus tractus solitarii in pancreatic secretion induced by 5-hydroxytryptamine in rats

AIM: To investigate the role of nucleus tractus solitarii (NTS) in pancreatic secretion induced by 5-hydroxytryptamine (5-HT) in rats and to further elucidate the related neural substance.

METHODS: Twenty-four rats were randomly divided into NaCl group, 5-HT group and sham operation group. Rats in NaCl and 5-HT groups were given NaCl (0.86 mol/L) and 5-HT (10^-4 mol/L) via duodenum respectively and the mixture of bile and pancreatic juice was collected every 15 min. Protein content of the mixture was measured with BCA protein assay. EnVision Immunohistochemical method and double-label immunohistochemistry (immunoenzyme-fluorenscence) were used to detect the quantity of c-Fos and NK1-R positive cells in intermediate-medial NTS (mNTS), rostral (rNTS) and caudal regions (cNTS).

RESULTS: The number of c-Fos positive cells was significantly increased in NaCl and 5-HT group as compared to that in sham operation group in rNTS, mNTS and cNTS (P < 0.01), and in cNTS, the number was significantly larger in 5-HT group than that in NaCl group 22.00±1.80 vs 18.50 ± 1.71, P < 0.01). Moreover, NK1-R was expressed in the regions where c-Fos expression was enhanced by duodenal stimulation of NaCl and 5-HT, but this did not happen in sham operation group. After infusion of NaCl and 5-HT, pancreatic protein secretion was increased (P < 0.01). And the content of pancreatic protein was significantly higher than that in 5-HT and NaCl groups (29.6 ± 1.4 mg/15 min vs 18.1 ± 2.4 mg/15 min, P < 0.01).

CONCLUSION: NTS plays a role of sensing and processing information on pancreatic protein secretion induced by 5-hydroxytryptamine, in which the receptor of P substance may take a part.

Molecular cloning of human canstatin gene

AIM: To clone human canstatin gene and to detect and analyze its coding sequence.

METHODS: The total RNA was extracted from human placenta. The canstatin gene fragment was synthesized and amplified from the total RNA by RT-PCR. pUCm-T vector was cloned into the RT-PCR product to obtain recombinant pUCm-T/ canstatin. The pUCm-T/canstatin was then transformed into E.coli DH 5a, and sequence of the gene was detected.

RESULTS: The extracted total RNA was separated into three clear bands indicating 28 S, 18 S, and 5 S after electrop-horesis. The values of A₂₆₀ and A₂₈₀ were 0.879 and 0.410 respectively (A₂₆₀:A₂₈₀ = 2.095). The concentration of total RNA was 1.8 g/L. The PCR product was the same as target gene canstatin. BamH I and Hind III digestion proved the final product positive. The sequence of the cloned gene (684 bp) completely matched with that of canstatin gene in Genbank.

CONCLUSION: Human canstatin gene is successfully cloned, which establishes the foundation for further study of its anti-tumor activity.

Construction of an oral recombinant DNA vaccine strain of live attenuated Salmonella typhimurium carrying H. pylori neutrophil activating protein

AIM: To construct a live attenuated Salmonella typhimurium (S. typhimurium) strain carrying H. pylori-neutrophil activating protein (HP-NAP) gene as an oral recombinant DNA vaccine.

METHODS: By genetic engineering method, a 435 bp napA gene (encoding HP-NAP) was subcloned into an eukaryotic expression vector pIRES. After sequencing and BLAST analysis, the identified recombinant plasmid was then transformed into a live attenuated S. typhimurium strain SL7207.

RESULTS: By using polymerase chain reaction (PCR) and restriction enzyme digestion, a recombinant eukaryotic expression plasmid pIRES-napA containing napA gene of H. pylori was constructed, and the recombinant plasmid was transformed successfully into the live attenuated S. typhimurium strain SL7207. Most of the H. pylori-napA sequences in recombinant plasmid pIRES-napA were homologized with that of SS1 strain reported by GenBank, and the homology of nucleotide and protein was 98%, respectively.

CONCLUSION: A recombinant live attenuated S. typhimurium strain carrying HP-NAP gene as DNA vaccine is successfully constructed. The results lay the foundation for developing multivalent oral DNA vaccine against H. pylori infection.

Distribution of cagG gene in Helicobacter pylori isolates from Chinese patients with different gastroduodenal diseases and its clinical and pathological significance

AIM: To determine the distribution of cagG gene of Helicobacter pylori (H pylori) isolates cultured from patients with various digestive diseases and its relationship with gastroduodenal diseases.

METHODS: cagG was amplified by polymerase chain reaction in 145 H pylori isolates cultured from patients with chronic gastritis (n = 72), duodenal ulcer (n = 48), gastric ulcer (n = 17), or gastric and duodenal ulcer (n = 8), and the relationship between cagG status and the grade of gastric mucosal inflammation was determined.

RESULTS: cagG was present in 91.7% of the 145 H pylori isolates, with the rates were 90.3%, 93.8%, 88.2% and 100.0%, respectively, in those from patients with chronic gastritis, duodenal ulcer, gastric ulcer, and gastric and duodenal ulcer. There was no significant difference among the four groups (P > 0.05). The average grade of gastric mucosal inflammation in the antrum and corpus was 1.819 ± 0.325 and 1.768 ± 0.312, respectively in cagG positive patients, whereas the average inflammation grade was 1.649 ± 0.297, 1.598 ± 0.278 respectively in cagG negative cases (P > 0.05).

CONCLUSION: cagG gene of H pylori was quite conservative, and most H pylori strains in Chinese patients were cagG positive. cagG status was not related to clinical outcome or the degree of gastric mucosal inflammation. Therefore, cagG can not be used as a single marker for discrimination of H pylori strains with respect to a specific digestive disease.

Detection of K-ras gene mutation at codon 12 by pancreatic duct brushing for pancreatic cancer

OBJECTIVE

To assess the diagnostic value of endoscopic pancreatic duct brushing in detecting mutation of the K-ras gene at codon 12 in cytologic specimens from patients with pancreatic cancer.

METHODS

Thirty-five patients treated at Changhai Hospital, Shanghai between 1999 and 2001 were enrolled. Their cells obtained by pancreatic duct brushing during endoscopic retrograde cholangiopancreatography (ERCP) were suspended with phosphate buffer solution (PBS). DNA of the cells was extracted and mutation of the K-ras gene at codon 12 detected by means of PCR-SSCP.

RESULTS

The K-ras gene mutation rate of pancreatic cancer was 70%, which was higher than that of chronic pancreatitis (14%, P<0.05). K-ras gene mutation was not found in patients with pancreatic cystocarcinoma and duodenum carcinoma. As to the location of pancreatic cancer, no significant difference was observed between the head, the body and tail. The sensitivity, specificity, accuracy of pancreatic duct brushing in detecting pancreatic cancer was 70%, 94%, and 83%, respectively.

CONCLUSION

K-ras analysis of pancreatic brushing samples is helpful in the diagnosis of patients with early pancreatic cancer.

Adenovirus-mediated gene transfer in the treatment of pancreatic cancer

INTRODUCTION

Suicide gene therapy is a new experimental form of cancer chemotherapy that is currently being evaluated in human trials.

AIM

To evaluate the killing effects of the cytosine deaminase (CD) gene mediated by an adenovirus vector on human pancreatic carcinoma in vitro and in vivo.

METHODOLOGY

The CD gene was cloned into pAdTrack-CMV-CD, pAdTrack-CMV-CD, and pAdEasy-1, which underwent recombination in bacteria BJ5183. The newly recombinant Ad-CD containing green fluorescent protein was propagated in 293 cells and purified by cesium chloride gradient centrifugation. The human pancreatic carcinoma cell line PaTu8988/SW1990 was infected with this virus, and then 5-fluorocytosine (5-FC) was added; XTT assay was used to estimate relative numbers of viable cells. An in vivo model of pancreatic cancer was established by injecting 1.0 x 10(7) PaTu8988/SW1990 cells subcutaneously in Balb/c nude mice. When tumors were palpable, Ad-CD was injected into each tumor, and 5-FC was administered. The positive clones were selected by endonuclease digestion of the combinations, and the concentration of viral liquids containing the CD gene was 2 x 10(11) pfu/mL.

RESULTS

It was found that significant cytotoxic activities were possessed by 5-FC for CD gene-transduced PaTu8988/SW1990 cells, but there was little effect on the nontransduced pancreatic carcinoma cells. The antitumor effect was observed in PaTu8988/SW1990 xenografts from nude mice with in situ CD gene transduction.

CONCLUSION

These results indicate that the CD gene mediated by adenovirus has a high level of infectivity and is efficient for gene therapy for pancreatic carcinoma.

Killing effects of cytosine deaminase gene mediated by adenovirus vector on human pancreatic cancer cell lines in vitro

OBJECTIVE

To evaluate the killing effects of the cytosine deaminase (CD) gene mediated by adenovirus vector on human pancreatic cancer cell lines in vitro.

METHODS

The CD gene was cloned into pAdTrack-CMV-CD, and pAdTrack-CMV-CD and pAdEasy-1 were recombinated in bacteria. The newly recombinated Ad-CD containing green fluorescent protein (GFP) was propagated in 293 cells and purified by cesium chloride gradient centrifugation. Human pancreatic cancer cell lines Patu8988 and SW1990 were infected with this virus, then 5-FC was added. XTT assay was used to estimate relative numbers of viable cells.

RESULTS

The positive clones were selected by using endonuclease to digest the combinatants and the concentration of viral liquids containing the CD gene was 2X10(11) pfu/ml. It was found that significant cytotoxic activities were possessed by 5-FC for the CD gene transduced pancreatic cell lines, but little effects exerted on the nontransduced pancreatic carcinoma cells.

CONCLUSIONS

The CD gene mediated by adenovirus with a high infectivity is efficient for gene therapy of pancreatic carcinoma cell lines. These data demonstrate the therapeutic efficacy of an enzyme prodrug strategy in experimental pancreatic cancer.

A t(3;8) chromosomal translocation associated with hepatitis B virus intergration involves the carboxypeptidase N locus

Integrated hepatitis B virus (HBV) DNA is found in the great majority of human hepatocellular carcinomas, suggesting that these viral integrations may be implicated in liver oncogenesis. Besides the insertional mutagenesis characterized in a few selected cases and the contribution of viral transactivators to cell transformation to malignancy, HBV has been shown to generate gross chromosomal rearrangements potentially involved in carcinogenesis. Here, we report a t(3;8) chromosomal translocation present in a hepatocellular carcinoma developed in noncirrhotic liver tissue. One side of the translocation, in 8p23, is shown to be in the vicinity of the carboxypeptidase N gene, a locus that is heavily transcribed in liver tissue and frequently deleted in hepatocellular carcinomas and other epithelial tumors. The other side of the translocation, in 3q27-29, is widely implicated in several types of translocations occurring in different malignancies, such as large-cell lymphomas. The present data strongly support a model in which HBV-induced chromosomal rearrangements play a key role during multistep liver oncogenesis.

Alpha-fetoprotein reaction to Pisum sativum agglutinin in differentiation of benign liver diseases from hepatocellular carcinoma

Alpha-fetoprotein reactive to Pisum sativum agglutinin levels (AFP-R-PSA) was measured in sera from 124 patients with hepatocellular carcinoma (HCC) and 54 patients with benign liver diseases (BLD). The level of AFP-R-PSA in the HCC group (42% +/- 22%) was significantly higher than that in the BLD group (10% +/- 8%). When an AFP-R-PSA level above 25% was used as a value highly suggestive of HCC, the sensitivity of the test was 82%, the specificity was 96%, the accuracy was 86%, and the positive prediction value was 98%. The positive rates of AFP-R-PSA in HCC patients with a serum AFP level below 100 micrograms/L and with a serum AFP level below 400 micrograms/L were 78% and 84%, respectively. Corresponding value was 74% for 31 patients with a tumor size less than 5cm. If AFP was combined with AFP-R-PSA, the detection rate of small HCC in this study would be increased from 32% to 87%. These data indicate that measurement of AFP-R-PSA is useful for the differentiation of BLD and for the early diagnosis of HCC.

Mapping of B-cell epitopes of the human hepatitis B virus X protein

The immune response to the X protein of human hepatitis B virus (HBV) was studied by epitope mapping by using a set of MS2-HBx fusion proteins and synthetic peptides. Antibodies in sera of patients with acute and chronic HBV infection showed a multispecific immune response. Each serum contained antibodies to a different set of epitopes, which taken together cover most of the HBx sequence. Some of the epitopes were detectable only by immunoblotting with fusion proteins; others were detectable only by an enzyme-linked immunosorbent assay (ELISA) with synthetic peptides. The carboxy-terminal half of the HBx protein was preferentially recognized by antibodies from patients with chronic hepatitis and contained a short immunodominant antigenic region with at least two major nonoverlapping epitopes. Anti-HBx antibody titers as revealed by peptide ELISAs were highest and most frequent in patients with chronic hepatitis and usually low in acutely infected patients and asymptomatic carriers. The data demonstrate a remarkable qualitative and quantitative heterogeneity of the humoral HBx immune response which can be monitored by HBx-specific peptide ELISAs. Such tests may become useful diagnostic tools.

Immunogenicity of human hepatitis B virus P-gene derived proteins

The frequency and specificity of antibodies to P-gene encoded proteins of human hepatitis B virus was tested in sera of acute and chronically infected patients with and without hepatocellular carcinoma (HCC). For antibody detection an immunoprecipitation gel assay was performed with radioactively labeled polypeptides produced by in vitro translation of RNA of different P-gene regions. Thus, five antigenic regions were identified. All anti-P antibody positive sera reacted with carboxy-terminal P-poly-peptides, a subset with polypeptides of the amino-terminal and middle region, and none reacted with P-protein derived from the most sequence variable region. Anti-P antibodies were detected at very high frequency in sera of acute (73%) and chronically infected patients without HCC (87%), but less often in HCC patients (27%). These data indirectly demonstrate the expression of most hepatitis B virus P-gene sequences and the immunogenicity of P-proteins in vivo. Moreover, they establish hepatitis B virus anti-P-antibodies as a frequent serologic marker of infection and identify the carboxy-terminal region of the P-protein(s) as immunodominant.

Immunogenicity of human hepatitis B virus P-gene derived proteins

The frequency and specificity of antibodies to P-gene encoded proteins of human hepatitis B virus was tested in sera of acute and chronically infected patients with and without hepatocellular carcinoma (HCC). For antibody detection an immunoprecipitation gel assay was performed with radioactively labeled polypeptides produced by in vitro translation of RNA of different P-gene regions. Thus, five antigenic regions were identified. All anti-P antibody positive sera reacted with carboxy-terminal P-poly-peptides, a subset with polypeptides of the amino-terminal and middle region, and none reacted with P-protein derived from the most sequence variable region. Anti-P antibodies were detected at very high frequency in sera of acute (73%) and chronically infected patients without HCC (87%), but less often in HCC patients (27%). These data indirectly demonstrate the expression of most hepatitis B virus P-gene sequences and the immunogenicity of P-proteins in vivo. Moreover, they establish hepatitis B virus anti-P-antibodies as a frequent serologic marker of infection and identify the carboxy-terminal region of the P-protein(s) as immunodominant.

[Alpha-fetoprotein (AFP) variant in the diagnosis of small liver cancer]

From May 1983 to June 1986, 40 patients with primary liver cancer, less than 5 cm in diameter, were treated by operation. The smallest lesion was 1.4 x 0.9 x 0.4 cm in size. Fifteen patients came to the hospital for treatment due to the finding of AFP greater than or equal to 31 ng/ml by public survey and 8 with space occupying lesion (SOL) in the liver by ultrasonography (US). The serum AFP levels ranged from 0 to 6800 ng/ml in this group with AFP negative in 6 cases, 31-400 ng/ml in 19 and over 400 ng/ml in 15. The positive rate of AFP was 37.5%. US displayed SOL in 25 cases, suspicious SOL in 5 and negative in 10. The positive rate was 62.5% by US. The overall positive rate was 77.5% by AFP and US combined. In addition, AFP variant was determined by LCA affino-crossed-immunoelectrophoresis autoradiography. LCA-nonreactive-AFP varied from 0 to 100% with a mean value of 57.0 +/- 26.7%. Taking less than 75% as diagnostic criterion for liver cancer, the positive rate of LCA-nonreactive-AFP was 65.0%. 12 patients who were AFP variant positive but SOL suspicious or negative were regularly followed by US for 1-20 months. They all showed distinct SOL. Composite results of AFP, AFP variant and US gave a diagnostic rate of 97.5% for small liver cancer. The determination of AFP variant is helpful in early detection of small liver cancer.