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The functionalization of calixarenes at the “lower rim” reduces their conformational mobility creating new shapes which have been exploited to organize binding groups in space, thus producing efficient and selective Molecular Receptors. Calix[4]arene- ester and amide ligands in the fixed cone conformation show high efficiency and selectivity in the complexation of Na+ and Ca2+; the amide is able to encapsulate lanthanide ions (Eu3+and Tb3+) in its polar cavity, giving water soluble luminescent complexes. Calix[4]arene-based siderophores, which strongly complex iron (ΙII) in ethanol/water, have been obtained by the introduction of three hydroxamate chelating chains on the bottom rim of the calix fixed in the cone conformation. The selective 1,3,5-methylation of p-tert-butylcalix[6]- arene has been achieved and the subsequent introduction of ester and amide binding groups fixes the calix in a “flattened cone” conformation. The resulting ligands have a C3 symmetry and are able to transport guanidinium cation through a Supported Liquid Membrane. Water soluble calix[4] arenes in the fixed cone conformation, which selectively bind organic cations and neutral molecules in aqueous solution, have been synthesized, together with lipophilic cage molecules derived from calix[4]arenes which are potentially host for the encapsulation of organic molecules in apolar media.

An outer surface lipoprotein of 22 kDa was identified in the avian pathogen Borrelia anserina Ni-NL by using antibody preparations reactive with bacterial surface-exposed proteins. Amino acid sequence analysis of the 22-kDa protein demonstrated 90% identity with VmpA of B. turicatae , suggesting that the protein belongs to the family of 20-kDa outer surface proteins of the genus Borrelia . All of the 60 chicks intramuscularly treated with antibodies specifically reacting with the 22-kDa protein and infected with strain Ni-NL were completely protected from infection, since no spirochetemia was detected, and from death. Control chicks were treated with immune sera raised against apathogenic strain B. anserina Es, which expresses a prominent 20-kDa polypeptide that is also a member of the Vmp family but does not cross-react immunologically with the 22-kDa protein of the Ni-NL strain. These animals, infected with B. anserina Ni-NL, showed a high degree of spirochetemia 10 days after infection, and all died between 14 and 21 days after infection. The results showed that the 22-kDa surface protein of B. anserina Ni-NL is a determinant of the pathogenic potential of the strain and also confirmed that only strain-specific antibodies are protective against B. anserina infection.