NS2 is a nonstructural protein of Periplaneta fuliginosa densovirus(PfDNV) with a molecular mass of 30 kD,whose function is not yet clearly understood. In order to study the expression,subcellular distribution and the function of NS2 protein,the coding region of NS2 was amplified from the hindgut tissue of cockroaches infected with PfDNV by RT-PCR and then the recombinant prokaryotic expression vector pET28a-NS2 was constructed. The recombinant plasmid was transformed into E. coli BL21(DE3) to express the 6?His fusion protein in the bacteria. After purification,the fusion protein was injected into New Zealand rabbits to prepare polyclonal antibody. The specificity of the anti-NS2 antibody was successfullyproved by western blotting on the eukaryotic expressed products of NS2 protein.Meanwhile,the full sequence of ns2 gene was also cloned into the eukaryotic expression vector pAC. The recombinant plasmid pAC-NS2 was then transfected into Schneider line 2(S2) cells to express NS2 protein in the insect cells. The subcellular localization of NS2 in the insect cells was then investigated by indirect immunofluorescence technique using the anti-NS2 polyclonal antiserum. The confocal laser scanning microscope observation showed that NS2 protein was located primarily in the cytoplasm with some punctate nuclear staining.

Objective To make a comparison for the neutrophils prepared either by induction of differentiation of myeloid leuke-mia cell line,or by separation and purification of peripheral blood cells,or by induction of myeloid differentiation of peripheral blood stem cells.Methods NB4 cells were induced differentiation by 1μmol/L all-trans retinoic acid (ATRA)to mature granulo-cytes;neutrophils were separated and purified from peripheral blood by lysis of red blood cells followed by negative selection using magnetic bead-labeled antibodies;hematopoietic stem cells were separated and purified from peripheral blood by Percoll gradient centrifugation followed by negative selection using magnetic bead-labeled antibodies,and were induced to myeloid differentiation by GM-CSF and G-CSF.Morphology and purity of neutrophils prepared by these three methods were studied by means of MGG stai-ning.CD18 protein expression and subcellular distribution were studied by means of immunofluorescence staining.Results Purity of neutrophil was above 40% by induction of differentiation of NB4 cells,and was about 90% if purified from peripheral blood,and was above 70% if induced by myeloid differentiation of peripheral blood stem cells.There was no obvious difference for CD18 ex-pression in neutrophils prepared by these three methods,and staining of CD18 had a dotted pattern distributed in these cells.Con-clusion Peripheral blood neutrophils prepared by lysis of red blood cells followed by negative selection using magnetic bead-labeled antibodies are with high purity and viability which is suitable for immediate test of neutrophils from fresh blood.Neutrophils pre-pared by myeloid differentiation of hematopoietic stem cell are with high viability and last for days,which can be used in long test for neutrphils.