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C-Terminal Fragment of Human Laminin-Binding Protein Contains a Receptor Domain for Venezuelan Equine Encephalitis and Tick-Borne Encephalitis Viruses

A. A. Malygin1, E. I. Bondarenko2, V. A. Ivanisenko3, E. V. Protopopova2, G. G. Karpova1, and V. B. Loktev2*

1Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Lavrent’eva 8, 630090 Novosibirsk, Russia; fax: (383) 333-3677; E-mail: karpova@niboch.nsc.ru

2State Research Center of Virology and Biotechnology “Vector”, 630559 Koltsovo, Novosibirsk Region, Russia; fax: (383) 336-7409; E-mail: loktev@vector.nsc.ru

3Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Lavrent’eva 10, 630090 Novosibirsk, Russia; fax: (383) 333-1278; E-mail: salix@bionet.nsc.ru

* To whom correspondence should be addressed.

Received March 17, 2009; Revision received May 25, 2009
Polyclonal and monoclonal antibodies (MABs) to human laminin-binding protein (LBP) can efficiently block the penetration of some alpha- and flaviviruses into the cell. A panel of 13 types of MABs to human recombinant LBP was used for more detailed study of the mechanism of this process. Competitive analysis has shown that MABs to LBP can be divided into six different competition groups. MABs 4F6 and 8E4 classified under competition groups 3 and 4 can inhibit the replication of Venezuelan equine encephalitis virus (VEEV), which is indicative of their interaction with the receptor domain of LBP providing for binding with virions. According to enzyme immunoassay and immunoblotting data, polyclonal anti-idiotypic antibodies to MABs 4F6 and 8E4 modeling paratopes of the LBP receptor domain can specifically interact with VEEV E2 protein and tick-borne encephalitis virus (TBEV) E protein. Mapping of binding sites of MABs 4F6 and 8E4 with LBP by constructing short deletion fragments of the human LBP molecule has shown that MAB 8E4 interacts with the fragment of amino acid residues 187-210, and MAB 4F6 interacts with the fragment of residues 263-278 of LBP protein, which is represented by two TEDWS peptides separated by four amino acid residues. This suggested that the LBP receptor domain interacting with VEEV E2 and TBEV E viral proteins is located at the C-terminal fragment of the LBP molecule. A model of the spatial structure of the LBP receptor domain distally limited by four linear loops (two of which are represented by experimentally mapped regions of amino acid residues 187-210 and 263-278) as well as the central β-folded region turning into the α-helical site including residues 200-216 of the LBP molecule and providing for the interaction with the laminin-1 molecule has been proposed.
KEY WORDS: laminin-binding protein, receptor domain, anti-idiotypic antibodies, peptide, TEDWS, Venezuelan equine encephalitis virus, tick-borne encephalitis virus

DOI: 10.1134/S0006297909120050