OBJECTIVE:　To　investigate　immunity　of　a　recombinant　adenovirus　vaccine　(rAdV)　containing　codon-modified　neuraminidase　(Mod.　NA)　gene　of　H5N1　influenza　virus　in　BALB/c　mice　and　to　screen　for　appropriate　dose.　METHODS:　BALB/c　mice　were　immunized　with　the　rAdV-Mod.NA　vaccine　intramuscularly　twice　(double　injection　at　0　and　4th　week)　in　three　groups,　low　dosage　(10(5)　TCID50　per　dose),　medium　dosage　(10(7)　TCID50　per　dose)　and　high　dosage　(10(9)　TCID50　per　dose).　The　effect　of　humoral　and　cell-mediated　immunity　were　analysed　at　5th　week.　RESULTS:　(1)　The　rAdV-Mod.NA　vaccine　could　elicit　both　humoral　and　cell-mediated　robust　NA　specific　immunity　in　mice　by　neuraminidase　inhibitor　assay　and　IFN-gamma　ELISpot　assay;　(2)　10(7)　TCID50　per　dose　was　the　appropriate　dose;　(3)　Peptide　NA(109-124):　CRTFFLTQGALLNDKH　and　peptide　NA(182-199):　AVAVLKYNGIITDTIKSW　were　the　dominant　epitopes　for　neuraminidase-immunized　BALB/c　mice,　which　was　screened　out　from　the　whole　length　of　neuraminidase　of　an　H5N1　virus,　A/Anhui/1l/2005.　CONCLUSION:　The　recombinant　adenovirus　NA　could　induce　specific　humoral　and　cellular　immune　responses　in　BALB/c　after　immunization,　which　suggest　rAdV-Mod.NA　vaccine　was　a　potential　vaccine　candidate　against　H5N1　influenza　and　worthy　of　further　investigation.