the present invention will be further described in detail in conjunction with the following preparation examples and biological examples . it should be understood that these examples are only for the purpose of illustrating the invention rather than limiting the scope of the invention in any way . as used in the following examples , processes and methods not described in detail are conventional methods well known in the art . for example , solid phase phosphoramidite triester method is employed in synthetic process . as used in the following examples , the sources , trade names and / or compositions ( if necessary ) of the agents used herein are described only one time and not repeated for the same agents thereafter for the purpose of conciseness . the artificial cpg - containing single - stranded oligodeoxynucleotides ware synthesized by solid phase phosphoramidite triester method , which included the following steps : the protective group , dimethoxytrityl ( dmt ), in the nucleotide attached to a cpg ( controlled pore glass ) was removed by trichloroacetic acid ( tca ) to obtain a free 5 ′- hydroxyl group , which was available for the next condensation reaction . nucleotide monomers protected by phosphoramidite were mixed with tetrazole ( activator ) and placed into synthesis column to form a tetrazolyl phosphoramidite reactive intermediate ( 3 ′- teminus activated while 5 ′- teminus still protected by dmt ). this intermediate would be condensed with the nucleotides on cpg which had been deprotected . the tetrazolyl phosphoramidite reactive intermediate contacted with the nucleotides on cpg which had been deprotected and reacted with its 5 ′- hydroxyl group , wherein a condensation reaction occurred and the tetrazolyl was removed . in this way , the resulting artificial oligodeoxynucleotide extended forward a base . after above condensation reaction , acetylation was generally employed to block unreacted 5 ′- hydroxyl groups attached to cpg in order to avoid its extension during the next cycle . typically , the acetylation was accomplished by a mixture of acetic anhydride and n - methylimidazole . during above condensation reaction , the nucleotide monomers were connected with oligodeoxynucleotides attached to cpg by phosphite ester linkage . the phosphite ester linkage was unstable and susceptible to hydrolysis by acid or base . in order to obtain stable oligodeoxynucleotides , the phosphite ester therein was conventionally transformed into phosphate triester with a solution of iodine in tetrahydrofuran . after above five steps , a deoxynucleotide was attached to the nucleotide on cpg . similarly , trichloroacetic acid was used to remove the newly formed protective group dmt on 5 ′- hydroxyl group of deoxynucleotide , and above activation , coupling , blocking and oxidation steps were repeated to obtain a crude product of dna fragment . after post - synthesis processes such as cleavage of protective group ( typically benzoyl for a and c ; isobutyryl for g ; t unprotected ; nitrile ethyl for phosphite ), deprotection ( by conventional methods such as hap , page , hplc , c18 , opc ), purification and quantitation , the following oligonucleotide fragments ( shown as seq id no : 1 - 5 ) according to present invention which met experimental requirements were obtained : dvax - 1 ( seq id no : 1 ): 5 ′- tcgtcgggtgcgacgtcgcagggggg - 3 ′ dvax - 3 ( seq id no : 2 ): 5 ′- tcgtcgtttcgtcgttgggg - 3 ′ dvax - 4 ( seq id no : 3 ): 5 ′- tcgacgttcgtcgttcgtcgttc - 3 ′ dvax - 5 ( seq id no : 4 ): 5 ′- tcggggacgatcgtcgggggg - 3 ′ dvax - 6 ( seq id no : 5 ): 5 ′- ggatcgatcgatcgatgggggg - 3 ′. non - sulfurized cpg single - stranded oligodeoxynucleotides were synthesized by abi 3900 dna synthesizer , while completely sulfurized or partially sulfurized cpg single - stranded oligodeoxynucleotides were synthesized by abi 394 dna synthesizer through a substitution method . human peripheral blood ( from two normal blood - donors at blood center of changchun city ), which had been treated with heparin for anticoagulation , was added slowly along tube wall to the liquid surface of lymphocytes having a specific gravity of 1 . 077 ± 0 . 001 which was stratified with ficoll - hypaque ( purchased from beijing dingguo biotechnology cooperation limited ). the ratio of the separated liquid and the heparin - anticoagulated peripheral blood was about 2 : 1 . after horizontal centrifugation at 1 , 000 × g for 15 - 20 minutes , the liquid in tube was separated into three layers , wherein cells in the cell - rich layer was pipetted and transferred to another tube . equal volume of hank &# 39 ; s solution was added to the tube , mixed thoroughly , centrifuged at 800 - 1 , 000 × g for 15 min and supernatant was discarded . the cells were washed by centrifugation of hank &# 39 ; s solution . the hank &# 39 ; s solution ( serum - free , without ca 2 + and mg 2 + ) was prepared as follows : 8 . 0 g nacl , 0 . 4 g kcl , 0 . 06 g na 2 hpo 4 · h 2 o , 0 . 06 g kh 2 po 4 , 0 . 35 g nahco 3 , 1 . 0 g glucose and 0 . 02 g phenol red were added to and dissolved in 1000 ml ddh 2 o . the solution was sterilized under 8 pound for 15 min , stored in refrigerator at 4 ° c ., and adjusted to ph = 7 . 3 - 7 . 6 with 7 . 4 % nahco 3 just before use . after the last centrifugation , supernatant was discarded and 2 ml of 10 % fcs rpmi 1640 complete medium was added to resuspend cells . the rpmi 1640 medium was prepared as follows : 10 . 4 g rpmi 1640 containing l - glutamine ( gibcobrl ), 2 . 0 g nahco 3 , 100 , 000 iu gentamycin were added to 1000 ml h 2 o which had been distilled thrice . the solution was sterilized by filtering through 0 . 22 μm filter membrane under vacuum , and distributed . a drop of cell suspension was taken , diluted and counted . total cell counts in four large grids were recorded . concentration of mononuclear cells ( cell count / 1 ml cell suspension )= total cell counts in four large grids / 4 × 104 × 2 ( dilution ratio ). 2 . determination of antiviral activity of artificial cpg - containing single - stranded oligodeoxynucleotides to influenza virus human peripheral blood mononuclear cells was adjusted to a final concentration of 3 × 10 6 / ml with imdm medium supplemented with 10 % fetal bovine serum ( 1000 ml , containing 100 , 000 iu gentamycin , sterilized by filtering through 0 . 22 μm filter membrane and distributed ). the resultant cell suspension was added to a 12 - well culture plate , 2 ml per well . the artificial cpg - containing single - stranded oligodeoxynucleotides were then added ( 6 . 25 μg / ml ). culture control : no artificial cpg - containing single - stranded oligodeoxynucleotide was added and cultivation was conducted at 37 ° c . in a 5 % co 2 incubator for 48 hours . supernatant was collected and tested for its antiviral activity to influenza virus . well - grown vero cells ( atcc ) were adjusted to a final concentration of 3 × 10 5 / ml with imdm supplemented with 5 % fetal bovine serum . the cells were seeded into 96 - well flat - bottomed plates , 100 μl / well . the supernatants stimulated by cpg - containing single - stranded oligodeoxynucleotides were diluted by tenfold with imdm supplemented with 5 % fetal bovine serum . 100 μl of diluted supernatant was added to each well . thus , the volume of each well was 200 μl , i . e . 100 μl of cell suspension plus 100 μl of diluted supernatants stimulated by cpg - containing single - stranded oligodeoxynucleotides . an interferon control , an influenza virus control and a normal vero cell control were arranged . 37 ° c ., 5 % co 2 ( changchun institute of biological products ) 200 μl , and cultured for further 48 - 72 hours . the cultivation was stopped when pathological changes occurred in 80 - 100 % cells of virus control wells while the cells in cell control wells grew well . crystal violet staining was used to assess the extent of cytopathic effect . culture was discarded . 200 μl of 0 . 5 % crystal violet solution was added to each well and incubated at 37 ° c . for 15 min . the crystal violet staining solution was washed away with flowing water . 0 . 5 % crystal violet staining solution : 0 . 5 g crystal violet , 0 . 85 g nacl , dissolved in 50 ml anhydrous ether . 3 ml formaldehyde and 47 ml distilled water were added . pictures were taken to record the results . samples were applied according to table 1 and results after crystal violet staining were shown in fig1 . the results in fig1 demonstrated that the artificial cpg - containing single - stranded oligodeoxynucleotides dvax - 1 , dvax - 3 , dvax - 4 , dvax - 5 and dvax - 6 ( seq id nos : 1 - 5 ) could stimulate human pbmc to produce antiviral substances , which provide significant protection for vero cells against the attack of virus . the artificial cpg - containing single - stranded oligodeoxynucleotides dvax - 1 , dvax - 3 , dvax - 4 , dvax - 5 and dvax - 6 ( seq id no : 1 - 5 ) were effective for the treatment and prevention of human respiratory infectious diseases such as influenza caused by influenza virus . antiviral activity of artificial cpg - containing single - stranded oligodeoxynucleotide to single - stranded positive strand rna virus - sars virus 2 . obtaining the culture supernatant of human pbmcs stimulated by cpg odn ( dvax - 1 ) human pbmcs in rpmi 1640 complete medium supplemented with 10 % fcs was seeded into 12 - well plate ( 2 ml / well ) and the concentration of cell was 4 × 10 6 cells / ml . cpg odn ( dvax - 1 ) sterilized by filtration was added to final concentrations of 25 μg / ml , 12 . 5 μg / ml , 6 . 25 μg / ml and 3 . 13 μg / ml , respectively . culture without cpg odn was used as control . after incubation at 37 ° c . under 5 % co 2 for 48 hours , supernatants were collected and stored at − 20 ° c . until use . 3 . determination of antiviral activity of artificial cpg - containing single - stranded oligodeoxynucleotide to sars virus this experiment was carried out at institute of virus control and prevention in the chinese center for disease control and prevention . african green monkey kidney passage cells ( vero e6 , provided by institute of virus control and prevention in the chinese center for disease control and prevention ) were seeded into 96 - cell plate with a cell concentration of 4 × 10 5 / ml . after incubation at 37 ° c . in 5 % co 2 for 24 hours , culture media were discarded . 100tccid50 sars - cov sino - 5 strain [(# 4 serum sample from acute sars patient ): provided by youanmen hospital of beijing , identified by and stored at institute of virus control and prevention in the chinese center for disease control and prevention ] was added and incubated at 37 ° c . in 5 % co 2 for 2 hours . viral solution was discarded and the culture supernatant of human pbmcs stimulated by cpg odn ( dvax - 1 ) was added in duplicate , 100 μl / well . recombinant human interferon α2b ( yuancein , positive control drug , 1 , 000 , 000 iu / vial , china drug authorization no : s19990013 , lot no : 000503a , manufactured by beijing yuance pharmaceutical corporation limited ) and medium controls , cell control and virus control were cultured at 37 ° c . in 5 % co 2 for 6 days . cytopathic effect ( cpe ) was observed under microscope , wherein “+” denoted pathological change in 25 % of cells , “++” denoted pathological change in 26 - 50 % of cells , “+++” denoted pathological change in 51 - 75 % of cells and “++++” denoted pathological change in 76 - 100 % of cells . after study of cpe , each well was added with 100 μl of 0 . 5 % crystal violet staining solution ( 0 . 5 g crystal violet , 0 . 85 g nacl , dissolved in a mixture of 50 ml absolute ethyl ether , 3 ml formaldehyde and 47 ml distilled water ) and incubated at 37 ° c . in 5 % co 2 for 15 min . after wash with flowing water , each well was added 100 μl destaining solution ( 50 ml ethylene glycol monomethyl ether , 50 ml distilled water ). after shaking at room temperature for 2 hours , elisa detector was used to read od values at 492 nm . the culture supernatant of human pbmc which was stimulated by 25 μg / ml cpg odn ( dvax - 1 ) for 48 hours and diluted at 1 : 160 , could effectively inhibit the sars - cov sino - 5 strain ; the culture supernatant of human pbmc which was stimulated by 12 . 5 μg / ml cpg odn ( dvax - 1 ) for 48 hours and diluted at 1 : 80 , could effectively inhibit the sars - cov sino - 5 strain ; the culture supernatant of human pbmc which was stimulated by 6 . 25 μg / ml cpg odn ( dvax - 1 ) for 48 hours and diluted at 1 : 40 , could effectively inhibit the sars - cov sino - 5 strain ; recombinant human interferon α2b which was diluted to above 50 , 000 iu , could effectively inhibit the sars - cov sino - 5 strain ; and the culture supernatant without cpg odn had no inhibitory effect on the sars - cov sino - 5 strain . the culture supernatant of human pbmc which was stimulated by 25 μg / ml cpg odn ( dvax - 1 ) for 48 hours and diluted at 1 : 80 , could effectively inhibit the sars - cov sino - 5 strain ; the culture supernatant of human pbmc which was stimulated by 12 . 5 μg / ml cpg odn ( dvax - 1 ) for 48 hours and diluted at 1 : 80 , could effectively inhibit the sars - cov sino - 5 strain ; the culture supernatant of human pbmc which was stimulated by 6 . 25 μg / ml cpg odn ( dvax - 1 ) for 48 hours and diluted at 1 : 20 , could effectively inhibit the sars - cov sino - 5 strain ; recombinant human interferon α2b which was diluted to above 50 , 000 iu , could effectively inhibit the sars - cov sino - 5 strain ; and the culture supernatant without cpg odn had no inhibitory effect on the sars - cov sino - 5 strain . in view of above , human pbmc stimulated by cpg odn ( dvax - 1 ) could be induced to produce antiviral substances against single - stranded positive strand rna virus — sars virus in supernatant , and cpg odn ( dvax - 1 ) could stimulate cell to produce antiviral substance to protect from the infection of single - stranded positive strand rna virus — sars virus . antiviral activity of artificial cpg - containing single - stranded oligodeoxynucleotide to single - stranded positive strand rna virus - dengue virus 2 . obtaining the culture supernatant of human pbmcs stimulated by cpg odn ( dvax - 1 ) 3 . determination of antiviral activity of artificial cpg - containing single - stranded oligodeoxynucleotide to dengue virus 200 μl vero e6 cell suspension was seeded into 96 - well plate , and cell concentration was 4 × 10 5 / ml . after inoculation at 37 ° c . in 5 % co 2 for 24 hours , culture media was discarded . 100tccid50 dengue virus ( d2v strain ngc , produced by c6 / 36 insect cell ( atcc )) was added and incubated at 37 ° c . in 5 % co 2 for 2 hours . viral solution was discarded and the culture supernatant of human pbmcs stimulated by cpg odn ( dvax - 1 ) was added in triplicate , 100 μl / well . cell control and virus control were cultured at 37 ° c . in 5 % co 2 for 8 days . cytopathic effect ( cpe ) was observed under microscope , wherein “+” denoted pathological change in 25 % of cells , “++” denoted pathological change in 26 - 50 % of cells , “+++” denoted pathological change in 51 - 75 % of cells and “++++” denoted pathological change in 76 - 100 % of cells . the culture supernatant of human pbmc which was stimulated by 25 μg / ml cpg odn ( dvax - 1 ) for 48 hours and diluted at 1 : 80 , could effectively inhibit dengue virus ; the culture supernatant of human pbmc which was stimulated by 12 . 5 μg / ml cpg odn ( dvax - 1 ) for 48 hours and diluted at 1 : 80 , could effectively inhibit dengue virus ; the culture supernatant of human pbmc which was stimulated by 6 . 25 μg / ml cpg odn ( dvax - 1 ) for 48 hours and diluted at 1 : 40 , could effectively inhibit dengue virus ; and the culture supernatant without cpg odn had no inhibitory effect on dengue virus . cpe occurred in 100 % cells of virus control . in view of above , human pbmc stimulated by cpg odn ( dvax - 1 ) could be induced to produce antiviral substances against single - stranded positive strand rna virus — dengue virus in supernatant , and cpg odn ( dvax - 1 ) could stimulate cell to produce antiviral substance to protect from the infection of single - stranded positive strand rna virus — dengue virus . antiviral activity of artificial cpg - containing single - stranded oligodeoxynucleotide to single - stranded positive strand rna virus — japanese encephalitis virus 2 . obtaining the culture supernatant of human pbmcs stimulated by cpg odn ( dvax - 1 ) 3 . determination of antiviral activity of artificial cpg - containing single - stranded oligodeoxynucleotide to japanese encephalitis virus 200 μl bhk - 21 cell suspension ( purchased from mongolia biopharmaceutical factory ) was seeded into 96 - well plate , and cell concentration was 4 × 10 5 / ml . after inoculation at 37 ° c . in 5 % co 2 for 24 hours , culture media was discarded . 100tccid50 japanese encephalitis virus ( provided by changchun institute of biological products ) and incubated at 37 ° c . in 5 % co 2 for 2 hours . viral solution was discarded and the culture supernatant of human pbmcs stimulated by cpg odn ( dvax - 1 ) was added in triplicate , 100 μl / well . cell control and virus control were cultured at 37 ° c . in 5 % co 2 for 4 days . cytopathic effect ( cpe ) was observed under microscope , wherein “+” denoted pathological change in 25 % of cells , “++” denoted pathological change in 26 - 50 % of cells , “+++” denoted pathological change in 51 - 75 % of cells and “++++” denoted pathological change in 76 - 100 % of cells . the culture supernatant of human pbmc which was stimulated by 25 μg / ml cpg odn ( dvax - 1 ) for 48 hours and diluted at 1 : 160 , could effectively inhibit japanese encephalitis virus ; the culture supernatant of human pbmc which was stimulated by 12 . 5 μg / ml cpg odn ( dvax - 1 ) for 48 hours and diluted at 1 : 80 , could effectively inhibit japanese encephalitis virus ; the culture supernatant of human pbmc which was stimulated by 6 . 25 μg / ml cpg odn ( dvax - 1 ) for 48 hours and diluted at 1 : 40 , could effectively inhibit japanese encephalitis virus ; and the culture supernatant without cpg odn had no inhibitory effect on japanese encephalitis virus . cpe occurred in 100 % cells of virus control . in view of above , human pbmc stimulated by cpg odn ( dvax - 1 ) could be induced to produce antiviral substances against single - stranded positive strand rna virus — japanese encephalitis virus in supernatant , and cpg odn ( dvax - 1 ) could stimulate cell to produce antiviral substance to protect from the infection of single - stranded positive strand rna virus — japanese encephalitis virus .
the present invention provides a series of artificial cpg - containing single - stranded oligodeoxynucleotides , each of which is consisted of single - stranded oligodeoxynucleotide dna molecule containing one or more cpg , wherein said odns can stimulate human peripheral blood mononuclear cell to produce antiviral substances . these odns can protect the cells against the attack from virus , wherein said virus is preferably selected from the group consisted of influenza virus and single - stranded positive strand rna virus such as sars virus , hepatitis c virus , dengue virus and japanese encephalitis virus . moreover , the antiviral use of artificial cpg odns and its use for treating and preventing viral infection are also provided .