The entire content of the following electronic submission of the sequence listing via the USPTO EFS-WEB server, as authorized and set forth in MPEP §1730 II.B.2(a)(C), is incorporated herein by reference in its entirety for all purposes. The sequence listing is identified on the electronically filed text file as follows:
The invention relates to the field of passive immunization against influenza. More particularly, antibodies that bind near to the HA0 maturation cleavage site consensus sequence of influenza hemagglutinin A, including antibodies secreted by human cells.
The hemagglutinin protein of influenza virus has a globular head domain which is highly heterogeneous among flu strains and a stalk region containing a fusion site which is needed for entry into the cells. The hemagglutinin protein (HA0) is activated to permit the fusion site to effect virulence by cleavage into HA1 and HA2 portions which remain coupled using disulfide bonds but undergo a conformational change. This cleavage site contains a consensus sequence which is shared both by influenza A and influenza B and by the various strains of influenza A and B.
Bianchi, E., et al., J. Virol. (2005) 79:7380-7388 describe a “universal” influenza B vaccine based on the consensus sequence of this cleavage site which was able to raise antibodies in mice when conjugated to the outer membrane protein complex of Neisseria meningitidis. Monoclonal antibodies which appear to bind to the consensus sequence were also described. In addition, successful passive transfer of antiserum was observed in mice. Prior vaccines, such as those described in WO2004/080403 comprising peptides derived from the M2 and/or HA proteins of influenza are subject to inducing antibodies that are either of weak efficacy or are not effective across strains.
The invention provides monoclonal antibodies that bind an epitope shared across multiple strains of influenza, and more particularly that bind representatives of either or both Group 1 and Group 2 influenza A. Such antibodies are able to confer passive immunity in the event of a pandemic caused, for example, by a previously unidentified influenza strain or a strain against which protection is not conferred by the seasonal vaccines currently available. Since the antibodies bind across many strains, indicative of targeting an essential site and thus likely to be included even in previously unencountered strain, such a vaccine would be effective in such circumstances. Such antibodies are also useful to ameliorate or prevent infection in subjects for whom vaccination failed to produce a fully protective response or who are at high risk due to a weak immune system (e.g., the very young, the elderly, transplant patients, cancer or HIV chemotherapy treated patients).
Thus, in one aspect, the invention is directed to monoclonal antibodies or immunoreactive fragments thereof that are broadly crossreactive with influenza A virus of Group 1 including H1, H2, H5, H6, H8, H9, H11, H13, H16 or Group 2 including H3 and H7 as type specimens, or that show cross-Group reactivity. The antibodies bind specifically to an epitope contained in the HA0 protein of the influenza virus and recognize the native trimeric form of HA. As is well understood in the art, non-immunoglobulin based proteins may have similar epitope recognition properties as an antibody and can also provide suitable embodiments, including binding agents based on fibronectin, transferrin, lipocalin, or nucleic acid based aptamers.
In other aspects, the invention is directed to methods to use the antibodies and fragments of the invention for passively inhibiting viral infection in subjects. The invention is also directed to recombinant materials and methods to produce these antibodies or fragments.
The present invention provides useful antibodies including providing effective means to identify cells that secrete such antibodies so that the relevant coding sequences can be retrieved and stored for subsequent and facile recombinant production of such antibodies. The method includes a binary logic based design of a screening procedure.
Such a procedure can readily be applied to human cells using, in particular, the CellSpot™ method described in U.S. Pat. No. 7,413,868, the contents of which are incorporated herein by reference. Briefly, the method is able to screen individual cells obtained from human (or other) subjects in high throughput assays taking advantage of labeling with particulate labels and microscopic observation. In one illustrative embodiment, even a single cell can be analyzed for antibodies it secretes by allowing the secreted antibodies to be adsorbed on, or coupled to, a surface and then treating the surface with desired antigens each coupled to a distinctive particulate label. The footprint of a cell can therefore be identified with the aid of a microscope. Using this technique, millions of cells can be screened for desirable antibody secretions and even rare antibodies, such as those herein desirable for passive influenza immunization across strains can be recovered. Since human subjects have existing antibodies to at least some influenza strains, and since the antibodies obtained by the method of the invention bind a conserved sequence, these antibodies serve the purpose of addressing new strains as well as strains with which human populations have experience.
The invention provides a method to identify a monoclonal antibody that binds to a location near the hemagglutinin (HA0) cleavage site consensus sequence. The method comprises contacting candidate monoclonal antibodies or fragments with: i) a peptide consisting essentially of an amino acid sequence upstream of or downstream of said consensus sequence, but lacking said consensus sequence; ii) a peptide consisting essentially of an amino acid sequence upstream of said consensus sequence and including said consensus sequence; and iii) a peptide consisting essentially of an amino acid sequence downstream of said consensus sequence and including said consensus sequence; wherein a monoclonal antibody that binds to the peptide of ii) and iii) but not to the peptide of i) is identified as a peptide that binds specifically to the HA0 cleavage site consensus sequence. Other combinations could also be used, as will be evident to the skilled artisan, as long as binary logic is followed. For example, i) could be a peptide consisting essentially of an amino acid upstream of the consensus sequence of a first strain and lacking the consensus sequence, with ii) being the whole HA0 sequence from the first strain and iii) being the whole HA0 sequence from a second strain. Shorter portions could also be used. For further confirmation, an isolated peptide from the conserved region can also be used, although the information derived from the larger protein domains is believed to be more informative regarding recognition of the intact antigen.
This method is not limited to employing the CellSpot™ technique, nor is it limited to human antibodies. The binary logic of this method can be employed in any alternative screening method. Likewise, it can be applied to other diversity libraries besides natural immunoglobulins.
The method of the invention relies on binary logic wherein peptides that contain the desired consensus sequence and additional upstream and/or downstream portions are used as test peptides and their ability to complex antibodies as compared to regions lacking the consensus sequence is assessed. Thus, patterns are obtained whereby cells secreting the appropriate antibodies can be instantly identified.
In one illustrative embodiment, three antigens are used to assess the secreted antibody population. The first peptide is all or substantially all of the amino acid sequence upstream of the consensus sequence contained in HA0 and is coupled to a particulate label of, say, red. A second test antigen contains these upstream sequences, but contains also the consensus sequence and is labeled with particle of a different color, for example, blue. A third test peptide contains the consensus sequence and all or substantially all of the downstream regions of the HA0 protein and is labeled with a third color particulate, for example, green. (By upstream portion is meant toward the N-terminus from the consensus sequence and by downstream portion the continuation of the amino acid sequence from the consensus sequence toward the C-terminus. By “substantially all” is meant lacking only one or a few non-essential amino acids.) Antibodies that bind to the consensus sequence will bind both the green and blue particulate labeled peptides but will not bind the red labeled upstream sequence lacking the consensus sequence. If desired, the specificity can be confirmed by adding a fourth peptide representing only the downstream portion without the consensus sequence bound, for example, to a yellow particulate label, wherein the yellow particulate label will not be bound to the antibody. Of course, it does not matter whether the upstream or downstream portion is chosen as the negative control.
The cleavage site for various strains of influenza A and influenza B is known. For example, the above cited article by Bianchi, et al., shows in Table 1 the sequence around the cleavage site of several such strains:
aThe position of cleavage between HA1 and HA2 is indicated by the arrow.
bThe consensus is the same for both the Victoria and Yamagata lineages.
As indicated, strict consensus occurs starting with the arginine residue upstream of the cleavage site and thus preferred consensus sequences included in the test peptides of the invention have the sequence RGI/L/F FGAIAGFLE (SEQ ID NO:7). It may be possible to use only a portion of this sequence in the test peptides.
Once cells that secrete the desired antibodies have been identified, it is straightforward to retrieve the nucleotide sequences encoding them and to produce the desired antibodies on a large scale recombinantly. This also enables manipulation of the antibodies so that they can be produced, for example, as single-chain antibodies or in terms of their variable regions only.
The retrieved nucleic acids may be physically stored and recovered for later recombinant production and/or the sequence information as to the coding sequence for the antibody may be retrieved and stored to permit subsequent synthesis of the appropriate nucleic acids. The availability of the information contained in the coding sequences and rapid synthesis and cloning techniques along with known methods of recombinant production permits rapid production of needed antibodies in the event of a pandemic or other emergency.
Applicants have recovered multiple monoclonal antibodies that are immunoreactive with HA0 protein of influenza from multiple clades (SEQ ID NOS:9-23, 26-40, 42-56, and 59-73). Other sequences include the amino acid sequence for the human IgG1 heavy chain constant region (SEQ ID NO:8), the amino acid sequence for the human light chain constant kappa region (SEQ ID NO:24), the amino acid sequence for the human light chain constant lambda region (SEQ ID NO:25), the nucleotide sequence for the human heavy chain constant region (SEQ ID NO:41), the nucleotide sequence for the human light chain constant kappa region (SEQ ID NO:57), and the nucleotide sequence for the human light chain constant lambda region (SEQ ID NO:58).
Two of these mAbs, MAB53 and MAB8, have substantial crossreactivity among important, distantly related influenza clades. As shown in
These results were confirmed using an alternative assay system, the biolevel interferometry based binding assay designated FortéBio® biosensor, as shown in
MAB53/H1=60 pM, H5=6 nM, H7=70 pM, H9=30 pM;
MAB8/H1=9 nM, H3=16 nM, H5=0.2 nM.
Both MAB53 and MAB8 are fully human antibodies, but similar antibodies characteristic of other species are also included in the invention. In the context of the invention, “antibodies” and their fragments include those portions of the molecule that are relevant for binding; thus, fragments would include variable regions only and “antibodies” as a general term would also be considered to include such fragments. Thus, Fab fragments, F(ab′)
To identify the epitope to which MAB53 binds, ELISA assays were conducted with respect to uncleaved HA0 protein, the HA1 fragment, and the HA2 fragment. As shown in
It has also been found that MAB8 and MAB53 bind to the same or nearby epitopes as demonstrated by their ability to compete with each other for binding to the HA0 protein of the H1 clade. This was shown using a FortéBio® assay using 2 μg/ml of antibody and 50 nM HA0 from H1. As shown in
Importantly, MAB53 and MAB8 differ in that MAB8 is released from the HA0 protein when the pH is lowered to 6, whereas MAB53 is not. This difference is significant as this appears predictive of neutralizing capability. In tests for the ability of MAB8 to neutralize H1N1 viral infection in a plaque reduction assay in MDCK target cells, low doses of MAB53 of 1-5 μg/ml neutralized infection by H1N1, by H7N3, H5N1 and H9N2. However, MAB8 does not neutralize infection by these strains. Thus, neutralizing strains may be preferentially selected by washing bound MAB or fragment at pH 6 during the primary screen, thus removing from HA0 MAB's that are unlikely to remain bound as the antibody-virus complex enters the cell via the endosomal compartment and thus will be expected to have reduced ability to neutralize the virus.
For example, in the CellSpot method HA0 may be bound to solid support (fluorescent beads) and captured by the MAB or a mixture of MAB's, then washed at pH 6.
MAB53 is produced recombinantly and has been sequenced. The full-length sequences of the heavy chain and light chain are as follows:
QVQLVQSGAEVRKPGSSVKVSCKVSGGIIRKYAINWVRQAPGQGLEWMGG
IIAIFNTANYAQKFQGRVTITADESTSTVYMELSSLRSEDTALYYCARGM
NYYSDYFDYWGQGSLVTVSPASTKGPSVFPLVPSSKSTSGGTAALGCLVK
EIVLTQSPGTLSLSPGERATLSCRASQSVRSNNLAWYQHKPGQAPRLLIF
GASSRATGIPDRFSGSGSGTDFTLTISRLEPEDFAVYYCQQYGSSPALTF
GGGTKVEIKRTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQW
The bold sequences are variable domains, and the un-bolded sequences represent the IgG1 constant chain for the heavy chain and the kappa constant chain for the light chain.
In addition, these variable regions have been analyzed according to the Kabat CDR assessment based on matching framework regions. As shown in
As shown in
It has also been shown that mice pretreated with graded doses of MAB53 survive challenge with otherwise lethal titers of H1N1 and H5N1 viruses with 100% protection against H1N1 challenge, as shown in
As shown in
Where challenge by H5N1 was substituted for challenge by H1N1, for MAB53 shown in
As shown in
Pepscan analysis was performed, establishing that MAB53 and CR6261 bind to similar regions of HA, but different epitopes (data not shown). This is consistent with the different activity of the two antibodies.
Thus, MAB53 and antibodies that bind to the same epitope under the same conditions are effective as passive vaccines suitable for protection of populations against epidemics and pandemics, and for prophylactic or therapeutic use against seasonal influenza for patients with a weakened immune system.
CAGCGCTCCTGCCTGGACGCATCCCGGCTATGCAGTCCCAGTCCAGGGCAGCAAGGC
AGGCCCCGTCTGCCTCTTCACCCGGAGGCCTCTGCCCGCCCCACTCATGCTCAGGGA
GAGGGTCTTCTGGCTTTTTCCCCAGGCTCTGGGCAGGCACAGGCTAGGTGCCCCTAA
CCCAGGCCCTGCACACAAAGGGGCAGGTGCTGGGCTCAGACCTGCCAAGAGCCATAT
CCGGGAGGACCCTGCCCCTGACCTAAGCCCACCCCAAAGGCCAAACTCTCCACTCCC
TCAGCTCGGACACCTTCTCTCCTCCCAGATTCCAGTAACTCCCAATCTTCTCTCTGC
AGAGCCCAAATCTTGTGACAAAACTCACACATGCCCACCGTGCCCAGGTAAGCCAGC
CCAGGCCTCGCCCTCCAGCTCAAGGCGGGACAGGTGCCCTAGAGTAGCCTGCATCCA
GGGACAGGCCCCAGCCGGGTGCTGACACGTCCACCTCCATCTCTTCCTCAGCACCTG
GTACCAACCTCTGTCCCTACAGGGCAGCCCCGAGAACCACAGGTGTACACCCTGCCC
This application claims priority to U.S. Provisional Patent Application Ser. No. 61/445,455 filed on 22 Feb. 2011, U.S. Provisional Patent Application Ser. No. 61/443,103 filed on 15 Feb. 2011, and U.S. Provisional Patent Application Ser. No. 61/355,978 filed on 17 Jun. 2010, the contents of which are incorporated in their entirety by reference herein.
Number | Date | Country | |
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61355978 | Jun 2010 | US | |
61443103 | Feb 2011 | US | |
61445455 | Feb 2011 | US |