ABSTRACT
A cold-adapted (ca), temperature sensitive (ts), live attenuated influenza B virus strain B/Ann Arbor/1/66 was chosen for influenza virus rescue research, in which six internal gene segments, PB1, PB2, PA, NP, M, NS, were fully synthesized and nine amino acid substitutions were artificially alter by human intervention. The resultant B/Ann Arbor/1/66 plasmids were named as pAB121-PB1, pAB122-PB2, pAB123-PA, pAB124-HA, pAB125-NP, pAB126-NA, pAB127-M and pAB128-NS, respectively. A recombinant influenza A virus was previously generated entirely from cloned cDNA. An infectious recombinant influenza B virus was generated here, and designated as rMDV-B, by plasmid-based reverse genetics. The rMDV-B virus contained HA and NA genes from an epidemic influenza B vires strain B/Malaysia/2506/2004 in the background of internal genes derived from influenza B virus strain B/Ann Arbor/1/66. HA titer of rMDV-B in MDCK cells and embryonated chicken eggs ranged from 1 : 64 to 1 : 512. The results may allow an effective live influenza B vaccine to be produced from a single master strain, providing a model for the design of future live human influenza vaccines.
ABSTRACT
Objective To set up a technical platform of reverse genetics based on the 8 plasmid.virus rescue system of cold-adapted influenza virus strain. Methods The cold-adapted, temperature sensitive, live attenuated influenza virus strain A/AnnArbor/6/60(H2N2)was chosen as the master donor virus(MDV)for rescue research,and its six internal gene fragments PB2,PB1,PA,NP,M and NS were artificially synthesized. Meanwhile, five amino acid mutations have been introduced as tags. Six fragments were ligated with modified pAD3000 for the construction of rescue plasmid. Six transcription/expression plasmids(pMDV-A-PB2,pMDV-A-PB1,pMDV-A-PA,pMDV-A-NP,pMDV-A-M,and pMDV-A-NS)were obtained, and their sequences were accurate. Results The reassorted virus named as rMDV-A contains HA and NA gene segments derived from PR8 strain along with six gene segments,PB2,PB1,PA,NP,M and NS,from MDV. The COS-1 cells were co-transfected with eight recombinant plasmids. The results showed that a cold-adapted, attenuated reassortant influenza A virus with hemagglutination activity was rescued successfullv bv"6+2" combination of MDV and PR8, and the allanotoic fluid of the injected eggs gave a posigenes of A/AA/6/60 used as backbone has provided experimental materials for further research on the gene function and novel vaccine candidate of cold-adapted, attenuated human influenza virus.
ABSTRACT
Six gene segments,PB1,PB2,PA,NP,M and NS,were fully synthesized which derived from the master donor virus (MDV),cold-adapted(ca),temperature sensitive(ts),live attenuated influenza virus strain A/Ann Arbor/6/60(MDV-A).Meanwhile,five amino acid substitutions (PB1-391E,58lG,661T,PB2-265S,NP-34G) were artificially altered by human intervention.HA and NA fragments derived from the 2006-2007 circulating strain A/New Caledonia/20/99 (H1N1).Eight fragments were ligated with modified pAD3000 for rescue plasmid construction.Eiight transcription/expression plasmids were named as pMDV-A-PB2,pMDV-A-PB1,pMDV-A-PA,pMDV-A-NP,pMDV-A-M,pMDV-A-NS,pMDV-A-HA,pMDV-A-NA,respectively.The COS-l cells were co-transfected with eight plasmids representing 6 internal viral backbone of the strain A/AA/6/60 and two plasmids containing the CDNA of the HA and NA segments of the strain A/New Caledonia/20/99 (H1N1),the results showed that cold-adapted,attenuated reassortant influenza A virus Was rescued successfully.Titers of a reassorted influenza A virus in embryonated chicken eggs mnged from 1:29to l:210.The rescue system of six intemal genes used as backbone opens the way for further research on gene function and neotype vaccine candidate of cold-adapted,live attenuated human influenza virus.
ABSTRACT
Six gene segments, PB1, PB2,PA, NP, M and NS, were fully synthesized which derived from the master donor virus(MDV), cold-adapted(ca),temperature sensitive(ts), live attenuated influenza virus strain A/Ann Arbor/6/60(MDV-A). Meanwhile, five amino acid substitutions (PB1-391E, 581G, 661T, PB2-265S, NP-34G) were artificially altered by human intervention. HA and NA fragments derived from the 2006～2007 circulating strain A/New Caledonia/20/99 (H1N1). Eight fragments were ligated with modified pAD3000 for rescue plasmid construction. Eight transcription/expression plasmids were named as pMDV-A-PB2, pMDV-A-PB1, pMDV-A-PA, pMDV-A-NP, pMDV-A-M, pMDV-A-NS, pMDV-A-HA, pMDV-A-NA, respectively. The COS-1 cells were co-transfected with eight plasmids representing 6 internal viral backbone of the strain A/AA/6/60 and two plasmids containing the cDNA of the HA and NA segments of the strain A/New Caledonia/20/99 (H1N1), the results showed that cold-adapted, attenuated reassortant influenza A virus was rescued successfully. Titers of a reassorted influenza A virus in embryonated chicken eggs ranged from 1∶29 to 1∶210. The rescue system of six internal genes used as backbone opens the way for further research on gene function and neotype vaccine candidate of cold-adapted, live attenuated human influenza virus.
ABSTRACT
Objective:To detect the influence of Ipas, and construct better Shigella vaccines.Methods: Guniea pigs were immunized with Ipa + and Ipa - bivalent Shigella vaccines strains by eyes mucosal immunization, and challenged with willed strains. The specific antibodies in tears were measured by BA ELISA assays after immunization and challenge. Results: The levels of specific local specific antibodies of immunized groups increased significantly compared to the control group and Ipa + group compared to Ipa - group after immunization.Conclusion: The expression of invasive plasmid antigens(Ipa) can enhance the levels of specific local antibodies. The two Shigella vaccines have good immunogenicity.