Detection of cagA gene, CagA protein in Helicobacter pylori isolates and its antibody in serum of patients with gastric diseases by a recombinant protein CagA 1 / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To construct a prokaryotic expression system of a fragment from Helicobacter pylori cagA gene and to detect the CagA positive Helicobacter pylori (CagA(+) H. pylori) and its antibody with the recombinant protein cagA 1.</p><p><b>METHODS</b>H.pylori isolates were obtained from biopsy specimens of 156 patients with gastric diseases. PCR method was used to detect frequency of cagA gene in 109 H. pylori isolates and to amplify a 2 148 bp fragment (cagA1) of cagA gene from a clinical strain Y06. A prokaryotic expression system of cagA1 was constructed. Expression of the target recombinant protein (rCagA1) was examined by SDS-PAGE. Western blot and immunodiffusion assay were applied to determine immunoreactivity and antigenicity of rCagA1. Two ELISA protocols were established to detect CagA expression in 109 H. pylori isolates and CagA antibody in serum of patients with gastric diseases. Correlations between infection of CagA(+) H. pylori and gastric diseases were analyzed.</p><p><b>RESULTS</b>H. pylori strains were isolated from 80.8% of the biopsy specimens (126/156) and 97.2% of the isolates (106/109) were cagA gene positive. In comparison with the reported data, homologies of nucleotide and putative amino acid sequences of the cloned cagA1 fragment were 94.83% and 93.30%, respectively. The output of rCagA1 was approximate 30.0% of the total bacterial proteins. rCagA1 was able to combine with the commercial antibody against whole cell of H. pylori and to induce the immunized rabbits to produce antibody with an immunodiffusion titer of 1:4. 92.6% of the H. pylori isolates (101/109) expressed CagA and 88.1% of serum samples (96/109) were CagA antibody positive. The percentage of CagA(+) H. pylori strains (97.9%) of peptic ulcer trended to be higher than that of gastritis (88.5%), but there was no statistically significant difference between two groups (chi(2)=3.48, P>0.05).</p><p><b>CONCLUSION</b>The recombinant rCagA1 can be used to detect CagA of H. pylori and its antibody. No association is found between CagA expression of H. pylori strains and types of gastric diseases in this study.</p>

Apoptosis and ultrastructural lesions in Vero and J774A.1 cells induced by Leptospira interrogans / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To determine the ability of adhering and invading to host cells and the related pathologic changes of Leptospira spp. with different virulence.</p><p><b>METHODS</b>A special Fontana silver staining method was developed to observe the ability of L.interrogans serogroup Icterohaemorrhagiae serovar lai strain 56601 and serogroup Pomona serovar pomona strain 56608, and L.biflexa serogroup Samaranga serovar patoc strain Patoc I to adhere Vero and J774A.1 cells. Ultrastructural lesions of the infected cells were examined by electron microscopy. By using flow cytometry with fluorescein labeling of FITC-Annexin V/PI,apoptosis and necrosis of the Vero and J774A.1 cells induced by the leptospiral strains before and after inactivation with ultraviolet treatment were detected, respectively.</p><p><b>RESULTS</b>The adhering rates of L.interrogans strains 56601 and 56608 to the Vero cells were 24.2% and 22.9% (P>0.05), while to the J774A.1 cells were 49.0% and 46.9% (P>0.05), respectively. L.biflexa strain Patoc I did not adhere to these two host cells. After the two strains of L.interrogans invaded two different cell lines, the special phagosomes containing the Leptospira were formed and similar cell ultrastructural lesions, such as chromatilysis and chromatin condensation, vacuolar degeneration, mitochondrion swelling and mitochondrial crista disappearance, and endoplasmic reticulum swelling and paramembranous ribosome disappearance, were observed. The apoptosis rates in the Vero cells caused by the L.interrogans strains 56601 and 56608 before and after ultraviolet inactivation were 84.4%, 82.8% and 77.9%, 86.1%, respectively. The L.interrogans strain 56601 mainly induced the terminal apoptosis in Vero cells with the rates of 68.0% and 52.9% before or after inactivation, while the L.interrogans strain 56608 mainly induced the early apoptosis in Vero cells with apoptosis rates of 64.1% and 50.1% before or after inactivation. In the J774A.1 cells, the L.interrogans strain 56608 caused cell necrosis (before and after inactivation) and apoptosis that was dominated by terminal apoptosis.</p><p><b>CONCLUSION</b>The established Fontana silver staining method can be used to observe adhesion of L.interrogans.L.interrogans can invade host cells through endocytosis which causes untrastructural lesions. The necrosis or apoptosis induced by L.interrogans are affected by different host cell lines but not the virulence of L.interrogans strains.</p>

Phospholipase C activity and alteration of intracellular free Ca2+ levels during internalization of Leptospira interrogans / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To determine the effects of leptospiral strains with different virulence on intracellular free Ca(2+)level and its relation with phospholipase C (PLC) activity of L.interrogans.</p><p><b>METHODS</b>L.interrogans-j infection cell modals were established with Vero and J774A.1 cell lines. Vero and J774A.1 cells were co-incubated with L.interrogans serogroup Icterohaemorrhagiae serovar lai strain 56601 (strong virulence) and serogroup Pomona serovar pomona strain 56608 (weak virulence) and L.biflexa serogroup Samaranga serovar patoc strain Patoc I (non-virulence). Intracellular free Ca(2+)levels were detected by laser scanning confocal microscopy with specific fluorescence labeling of fluoj3/AM. Using [(3)H] PIP2 as the substrate, the PLC activities in the culture supernatant, and cytoplasma and cytomembrane of the three strains of Leptospira were measured by isotope assay.</p><p><b>RESULTS</b>The baseline intracellular free Ca(2+)levels in the normal Vero and J774A.1 cells were (102.3+/-8.2)% and (105.9+/-7.3)%,respectively. The fluorescence intensity in the two cell lines incubated with L.biflexa strain Patoc I were fluctuated in range of (102.3+/-8.2)%approximate, equals(102.2+/-8.3)% during the observation period. The intracellular free Ca(2+)levels in the two cell lines infected with L.interrogans strain 56601 showed elevation with double peak patterns, with first peaks of (430.5+/-35.7)%, (747.5+/-18.5)% and the second peak of (380.6+/-17.4)%, (804.6+/-22.4)%, respectively. When the cells were infected with L.interrogans strain 56608, the intracellular free Ca(2+)levels were rising slowly with a single slope-like pattern, with the maximal of (235.0+/-19.3)% in Vero cells and (402.4+/-17.4)% in J774A.1 cells, which were significantly lower than those in the cells infected with L.interrogans strain 56601 (P<0.01). The culture supernatants, and cytoplasma and cytomembrane proteins of all three strains displayed PLC activities (P<0.05).</p><p><b>CONCLUSION</b>The cells infected with L.interrogans of different virulence show distinct intracellular free Ca(2+)levels and peak patterns. The different host cell lines can affect the intracellular free Ca(2+)levels, which is not related to the PLC activity in the leptospiral strains.</p>

Construction and identification of the prokaryotic expression system of rLTB/rCTB-rOmpL1/1 fusion genes / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To construct prokaryotic expression systems of ltB/ctB-ompL1/1 fusion genes and to determine the L.interrogans carrying status in leptospirosis patients with the expression products.</p><p><b>METHODS</b>The fusion genes ltB-ompL1/1 and ctB-ompL1/1 were constructed using linking primer PCR method. SDS-PAGE was used to examine expression of the target recombinant proteins rLTB-rOmpL1/1 and rCTB-rOmpL1/1. Western blot and GM1-ELISA were used to measure the immunogenic and GM(1)-binding activities of rLTB-rOmpL1/1 and rCTB-rOmpL1/1, respectively. PCR and MAT were performed to detect the expression of ompL1 gene in 97 wild L.interrogans strains. Antibodies against ompL1 gene products in serum samples of 228 leptospirosis patients were detected with ELISA method.</p><p><b>RESULTS</b>The homogeneity of nucleotide and putative amino acid sequence of ltB-jompL1/1 and ctB-ompL1/1 fusion genes were 99.7 % - 99.9 % and 99.5 % - 100 %, in comparison with the reported corresponding sequences. Expression outputs of both rLTB-rOmpL1/1 and rCTB-rOmpL1/1, mainly present in inclusion body, accounted for 10% of the total bacterial protein. Both rLTB-rOmpL1/1 and rCTB-rOmpL1/1 could combine to rabbit anti-rOmpL1/1 serum and bovine GM(1). 89.7 % of L.interrogans wild strains had ompL1 gene. 87.6% of the wild L.interrogans strains presented positive results for MAT (titers :1:4-1:256) with the rabbit anti-rOmpL1/1 or anti-rOmpL1/2 sera. 86.8% and 88.6% of the patients' serum samples were positive for rOmpL1/1 and rOmpL1/2 antibodies, respectively.</p><p><b>CONCLUSION</b>The fusion proteins, rLTB-rOmpL1/1 and rCTB-rOmpL1/1, showed high immunogenic and GM(1)-binding activities. ompL1 gene is extensively distributed and frequently expressed in different serogroups of L.interrogans and its products expressed by different genotypes exhibit extensive cross-antigenicity.</p>

Construction and application of prokaryotic expression system of Leptospira interrogans lipL32/1-lipL41/1 fusion gene / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To construct lipL32/1-lipL41/1 fusion gene and its prokaryotic expression system and to determine frequencies of carrying and expression of lipL32 and lipL41 genes in L.interrogans wild strains and specific antibody levels in sera from leptospirosis patients.</p><p><b>METHODS</b>lipL32/1-lipL41/1 fusion gene was constructed using linking primer PCR method and the prokaryotic expression system of the fusion gene done with routine techniques. SDS-PAGE was used to examine expression of the target recombinant protein rLipL32/1-rLipL41/1. Immunogenicity of rLipL32/1-rLipL41/1 was identified by Western blot. PCR and MAT were performed to detect carrying and expression of lipL32 and lipL41 genes in 97 wild L.interrogans strains. Antibodies against products of lipL32 and lipL41 genes in serum samples from 228 leptospirosis patients were detected by ELISA method.</p><p><b>RESULTS</b>The homogeneity of nucleotide and putative amino acid sequence of lipL32/1-lipL41/1 fusion gene were 99.9 % and 99.8 % in comparison with the reported sequences. Expression output of the target recombinant protein rLipL32/1-rLipL41/1, mainly present in inclusion body, accounted for 10 % of the total bacterial proteins. Both the rabbit antisera against rLipL32/1 and rLipL41/1 could combine to rLipL32/1-rLipL41/1. 97.9 % and 87.6 % of the L.interrogans wild strains had lipL32 and lipL41 genes, respectively. 95.9 % and 84.5 % of the wild strains were positive for MAT with titers of 1:4 - 1:128 using rabbit anti-rLipL32s or anti-rLipL41s sera, respectively. 94.7 % - 97.4 % of the patients'serum samples were positive for rLipL32s antibodies, while 78.5 % - 84.6 % of them were rLipL41s antibodies detectable.</p><p><b>CONCLUSION</b>lipL32/1-jlipL41/1 fusion gene and its prokaryotic expression system were successfully constructed. The expressed fusion protein had qualified immunogenicity. Both the lipL32 and lipL41 genes are extensively carried and frequently expressed by different serogroups of L.interrogans, and their expression products exhibit cross-antigenicity.</p>

Eukaryotic expression of Leptospira interrogans lipL32/1-ompL1/1 fusion gene encoding genus-specific protein antigens and the immunoreactivity of expression products / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To construct the eukaryotic expression system of L.interrogans lipL32/1-ompL1/1 fusion gene and to identify the immunoreactivity of expression products.</p><p><b>METHODS</b>PCR with linking primer was used to construct the fusion gene lipL32/1-ompL1/1. The P.pastoris eukaryotic expression system of the fusion gene, pPIC9K-lipL32/1-ompL1/1-P. pastorisGS115, was constructed after the fusion gene was cloned and sequenced. Colony with phenotype His(+)Mut(+) was isolated by using MD and MM plates and His(+) Mut(+) transformant with high resistance to G418 was screened out by using YPD plate. Using lysate of His(+) Mut(+) colony with high copies of the target gene digested with yeast lyase as the template and 5'AOX1 and 3'AOX1 as the primers, the target fusion gene in chromosome DNA of the constructed P. pastoris engineering strain was detected by PCR. Methanol in BMMY medium was used to induce the target recombinant protein rLipL32/1-rOmpL1/1 expression. rLipL32/1-rOmpL1/1 in the medium supernatant was extracted by using ammonium sulfate precipitation and Ni-NTA affinity chromatography. Output and immunoreactivity of rLipL32/1-rOmpL1/1 were measured by SDS-PAGE and Western blot methods, respectively.</p><p><b>RESULTS</b>Amplification fragments of the obtained fusion gene lipL32/1-ompL1/1 was 1794 bp in size. The homogeneity of nucleotide and putative amino acid sequences of the fusion gene were as high as 99.94 % and 100 %, respectively, compared with the sequences of original lipL32/1 and ompL1/1 genotypes. The constructed eukaryotic expression system was able to secrete rLipL32/1-rOmpL1/1 with an output of 10 % of the total proteins in the supernatant, which located the expected position after SDS-PAGE. The rabbit anti-rLipL32/1 and anti-rOmpL1/1 sera could combine the expressed rLipL32/1-rOmpL1/1.</p><p><b>CONCLUSION</b>An eukaryotic expression system with high efficiency in P.pastoris of L.interrogans lipL32/1-ompL1/1 fusion gene was successfully constructed in this study. The expressed fusion protein shows specific immunoreactivity, which can be used as a potential antigen for developing a novel vaccine of L.interrogans.</p>

Detection of transfusion transmitted virus infection of healthy blood donors in Hangzhou region and nucleotide sequence analysis of partial positive samples / 浙江大学学报·医学版

OBJECTIVE: To investigate the frequency of transfusion transmitted virus (TTV) infection in healthy blood donors in Hangzhou area and the mutation of TTV genomic fragment. METHODS DNA in serum samples of 203 healthy donors was extracted by phenol-chloroform method to detect TTV by semi-nested polymerase chain reaction and nucleotide sequences of partial amplification products were determined after T-A cloning. RESULTS TTV infection rate in 203 cases of blood donors in Hangzhou area was 15.3%. The homology of the amplified products of partial TTV positive samples compared with thereported nucleotide and putative amino acid sequences of TTV TA278 were 63.51% approximate, equals 67.12% and 59.46% approximate, equals 66.22% respectively. CONCLUSIONS TTV infection rate in the blood donors in Hangzhou is relatively high. The TTV infecting blood donors in the area may be a kind of novel genotype.