the wild type human and murine gm - csf cdna sequences were optimized by first identifying codons within the cdna which are not associated with the codon usage in highly expressed genes in humans and mice , respectively . each sub - optimal codon is replaced with those identified from highly expressed genes of the same species , which are known in the art and available online , for example , at http :// www . kazusa . or . jp / codon /. this usually requires only by a single base change in the third position but may also require changes in the second position . the codon optimized sequences can be prepared entirely by cdna synthesis or created from wild type cdna using molecular cloning methods well known in the art ( e . g ., maniatis , t . 1989 . “ molecular cloning : a laboratory manual ,” cold spring harbor laboratory press , ny , vol 1 , 2 , 3 ). this invention embraces the optimized gene sequences encoding mammalian gm - csf together with their use as an adjuvant in gene therapy or in connection with vaccines to obtain a stronger immunoresponse to expressed proteins . the methods , per se , do not constitute part of the invention , save for the use of the novel optimized sequences addressed herein . representative formulations , dosages and administration , such as those established for human patients , can be found with respect to gm - csf in hamm et al , j . clin . oncol . december 1994 ; 12 ( 12 ): 2667 - 76 and bergmann et al ., eur . j . cancer december 1995 ; 31a ( 13 - 14 ): 2164 . the utilization of the inventive subject matter is in manner not distinguishable per se from conventional dna delivery techniques in connection with gene therapy and vaccines . both ex vivo and in vivo utilities are embraced by the invention . in particular , the sequences of this invention can be used in conjunction with a wide variety of dna vaccines , where the effective composition includes as effective elements dna , either naked or in the form of modified vectors , together with an appropriate carrier and the codon optimized gm - csf dna of the invention . appropriate carriers include everything from saline solutions for conventional im preparations to gene guns and preparations therefor to liposome complexes . the inventive sequences of this invention are also suitable for use in ex vivo and in vivo cancer therapies , including radiation and chemotherapeutic treatment of cancer cells , particularly tumor cells , which have been transduced / transfected with gm - csf vectors , commonly in the form of adenoviral vectors carrying gm - csf as a heterologous transgene . other transfer means are set forth , e . g ., in u . s . pat . no . 5 , 910 , 488 . those of skill in the art will appreciate that there is a large , but finite number of combinations of codon bases that can be utilized to optimize expression . the invention embraces any optimization of mammalian , particularly human and murine , gm - csf sequences . among prefexred embodiments is that set forth in fig1 . this invention is further illustrated by reference to the example set forth below . in the example , the murine gm - csf sequence has been codon optimized . the same methods can be used to optimize other mammalian sequences encoding gm - csf , including , preferably , human with predictably similar results . the degree of enhanced activity will depend , in part , on the completeness of optimization . optimization of a single codon may have limited impact , in contrast with the optimization of a plurality of codons of a given sequence . all the alternatives are embraced within the invention exemplified herein . construction of murine gm - csf expression vectors . the native sequences coding for the 153 amino acids ( aa ) of murine gm - csf ( genbank accession no . x02333 ; fig1 upper sequence ) was amplified by pcr and cloned into pcdna3 . 1 (−) downstream from the human cmv immediate - early promoter ( pcmv ) sequence , using bamh i sites to generate pm - wtgmcsf . to generate pm - cgmcsf , the codon modified form of murine gmcsf , we changed the codon usage to that utilized by highly expressed human genes as described recently for hiv - 1 gp120 and gag - pol ( haas , j ., e . park , and b . seed . 1996 . codon usage limitation in the expression of hiv - 1 envelope glycoprotein . curr . biol . 6 : 315 - 32 ; kotsopoulou e , kim v n , kingsman a j , ingsman s m , and mitrophanous k a . 2000 . a rev - independent human immunodeficiency virus type 1 ( hiv - 1 )- based vector that exploits a codon - optimized hiv - 1 gag - pol gene . j virol 74 ( 10 ): 4839 - 52 ). the resulting modified murine gm - csf encoding a protein without any amino acid change ( fig1 lower sequence ). the resulting 480 - bp gene cassette included the xbai and xho i cloning sites and was constructed synthetically by the aptagen company ( herndon , va .). this modified murine gm - csf sequence was cloned into the xbai and xho i restriction sites of the eukaryotic expression vector pcdna3 . 1 (−) that employs the cytomegalovirus ( cmv ) immediate - early enhancer / promoter and bgh terminator ( invitrogen , san diego , calif . ), resulting in the plasmid pm - cgmcsf . the cmv promoter provides a high level of constitutive expression in a range of mammalian cells . the bghpa signal provides efficient transcription termination and polyadenylation of mrna . comparison of murine gm - csf expression by the various constructs in primate cells . we initially tested the protein expression by various murine gm - csf expression vectors in transfected cos - 7 cells , an african green monkey kidney - derived cell line . when cell lysates from transfected cos - 7 cells were analyzed by immunoblotting with a rabbit anti - murine gm - csf antibody , gm - csf precursor protein was not detected in pcdna3 . 1 - transfected cos - 7 cells , as expected ( fig2 lane 1 , top panel ). also , gm - csf protein was not detected in pm - wtgmcsf - transfected cos - 7 cells ( fig2 lane 2 , top panel ). gm - csf protein was detected in transfected cos - 7 cells with the pm - cgmcsf constructs ( fig2 top panel ). the secreted gm - csf protein was also detected in culture supernatants of pm - cgmcsf - transfected cos - 7 cells by the rabbit anti - murine gm - csf antibody ( fig2 bottom panel ). as expected , no gm - csf protein was detected in culture supernatants of pcdna3 . 1 ( lane 1 )- transfected cos - 7 cells ( fig2 bottom panel ). again , the pm - cgmcsf - transfected cos - 7 cells produced much more gm - csf proteins than the pm - wtgmcsf - transfected cos - 7 cells ( fig2 bottom panel ). these results suggest that the mutations modifying the codon usages in the murine gm - csf coding sequence increase gm - csf expression in cos - 7 cells . comparison of hiv - 1 gag expression by the various constructs in human cells . gm - csf expression was also evaluated with the various constructs in transfected 293 cells , a human embryonal kidney epithelial cell line and hela cells . immunoblot analysis of cell lysates prepared from transfected 293 cells is shown in fig3 ( top panel ). transfection of the 293 cells with pcdna3 . 1 or pm - wtgmcsf did not produce detectable levels of gm - csf protein by immunoblot analysis ( fig3 top panel , lanes 1 and 2 ). on the other hand , pm - cgmcsf - transfected 293 cells produced detectable gm - csf ( fig3 ). gm - csf protein was also detected in the supematants of pm - cgmcsf and pm - wtgmcsf - transfected 293 cells ( fig3 bottom panel ) but no gm - csf was detected in the supematants of pcdna3 . 1 - transfected 293 cells ( fig3 bottom panel ). again , the pm - cgmcsf - transfected 293 cells produced much more gm - csf proteins than the pm - wtgmcsf - transfected 293 cells . to compare levels of gm - csf protein expression in human cancer cells by the various murine gm - csf constructs , we performed transient transfection experiments using hela cells . three days after transfection , cell lysates from transfected hela cells were analyzed by immunoblotting for the presence of cell - associated gm - csf molecules ( fig3 top panel ). gm - csf was only detected in the cell lysates of hela cells transfected by pm - cgmcsf ( lane 6 , fig3 top panel ). no gm - csf was detected in the cell lysates of pcdna3 . 1 - and pm - wtgmcsf - transfected hela cells by rabbit anti - murine gm - csf antibody ( fig3 top panel , lanes 4 and 5 ). gm - csf was also detected in the supernatants of pm - cgmcsf - transfected hela cells ( fig3 bottom panel ). no gm - csf was detected in the supernatants of pcdna3 . 1 - transfected hela cells ( fig3 bottom panel ). anti - gag antibody responses in mice immunized with naked dna vaccine . balb / c mice were intramuscularly injected with total 100 μg of plasmid dna two times at 0 and 2 weeks . anti - gag antibodies were measured after virus challenge . sera were collected from the mice injected with the different dna constructs and analyzed by immunoblot using purified gag p55 recombinant protein from escherichia coli . as shown in fig4 anti - gag antibodies were detected in mice vaccinated with either pgag / wt - gm ( lane 3 ) or pgag / cgm dna mixture ( lane 4 ) and in mice infected with recombinant vaccinia virus / gag ( lane 5 ). in contrast , no anti - gag antibodies were detected in mice immunized with pcdna3 . 1 and pgag / vector dna mixture ( fig4 lanes 1 and 2 ). administration of pgag plasmid alone did not induced detectable igg antibody responses . the co administration of the wild type gm - csf plasmid induced only a modest increase in total igg anti - gag serum titers . by comparison , co administration of the codon modified gm - csf plasmid significantly increased total igg serum titers . elispot assay in dna - vaccinated mice . antigen - specific cd8 + t cell responses were measured by two methods : ifn - γ elispot assay and intracellular cytokine staining and flow cytometry analysis . mice were immunized with the various dna constructs as described above . at day 5 after recombinant vaccinia virus challenge , splenocytes from the mice in each group were harvested and pooled , and the ifn - γ elispot assay specific to hiv - 1 gag peptide were measured following antigen stimulation . as expected , those plasmids that did not express gag p55 in vitro , such as pcdna3 . 1 did not elicit an antigen - specific cd8 + t cell response against hiv - 1 gag ( fig5 ). a 3 - fold increase in numbers of cells secreting ag - specific ifn - γ to either peptide was detected in mice immunized with the addition of wild type gm - csf plasmid ( 500 sfu vs . 170 sfu , fig5 lane 3 vs . 2 ). the group of vaccinated mice that received pm - cgmcsf developed a slightly higher level of hiv - 1 gag - specific cd8 + activity than those that received pm - wtgmcsf . these results showed that intramuscular injection of the mixture of pgag and codon modified gm - csf plasmids had larger numbers of ifn - γ secreting cells that remained elevated longer after the second immunization and can induce both humoral and cellular immune responses against hiv - 1 gag in a murine model . intracellular cytokine staining and flow cytometry analysis . cd8 + t lymphocytes are one of the most crucial components of antiviral effector cells . we therefore assessed the number of hiv - 1 gag - specific cd8 + t cells expressing ifn - γ in the spleens of mice immunized with dna vector and challenged with vp1287 . these cells were measured by brief stimulation in vitro for 24 h with mhc class i - restricted hiv p24 peptide ( amino acid sequence : amqmlketi ), followed by staining for cd8 and intracellular ifn - γ . intracellular cytokine staining and elispot are sensitive functional assays used to measure the ifn - γ production at the single - cell level . we observed a high level of gag - specific cd8 + effector cells in the spleens of mice co immunized with the mixture pgag plasmid and pm - cgmcsf plasmid ( 1 . 14 % of the total splenocytes and 10 . 2 % of the total cd8 + t cells ) within 5 days of vp1287 challenge ( fig6 ). in contrast , less than 0 . 02 % of the total splenocytes were cd8 + t cells expressing ifn - γ in control vector - immunized mice . the level of gag - specific cd8 + effector cells in the spleens of mice immunized with pm - wtgmcsf plasmid ( 0 . 79 % of the total splenocytes and 8 % of the total cd8 + t cells ) was lower than that obtained with pm - c - gmcsf . the background level in mice immunized with pcdna3 . 1 and challenged with recombinant vaccinia virus expressing hiv - 1 gag was low , suggesting that gag - specific cd8 + ifn - γ - producing cells were generated from memory t cells . for application of the above example to other codons and other optimization solutions , reference to the following sequences may be of value . bolded trinucleotides , shown below in the native and codon optimzied sequences , are representative of those codons which may be modified according to the present invention . gaa acc tcc tgtgcc acccag atc atcacc ttc gaa agc ttc aag gag the invention claimed herein has been described generically , and by reference to specific embodiments . examples and specific features are not intended to be limiting unless so indicated above . modifications will occur to those of skill in the art , particularly in the selection of the source of mammalian gm - csf , the specific codons optimized , the specific bases within the codons replaced to effect optimization , and the number and placement of the codons optimized , without departing from the invention , except as excluded by the claims set forth below .
the present invention relates to improved methods for the treatment or prevention of disease with gene therapy or vaccines comprising host optimized gm - csf nucleic acid sequences . more particularly , the invention provides methods for codon optimized gm - csf with enhanced expression and adjuvant activity ex vivo and in vivo . the present invention also provides for methods of optimizing homologous gene expression ex vivo and in vitro or in transgenic animals .