Chlamydia trachomatis serotype G is most strongly associated with subsequent development of cervical SCC. Increasing numbers of exposures to different C trachomatis serotypes also increases risk. Our results strengthen the evidence that there is a link between past C trachomatis infection and cervical SCC.

Puumala virus (PUU) is a member of the Hantavi rus genus in the family Bunyaviridae and the etiologic agent of nephropathia epidemica (NE), a form of haemorrhagic fever with renal syndrome (HFRS). In this study we compared the immunofluorescence patterns of NE sera and antibodies raised against recombinant PUU proteins and confirm that the nucleocapsid protein is the major target in the early IgG response of NE patients and provides the molecular basis for simple and rapid differentiation between acute illness and old immunity by granular vs. diffuse fluorescence staining in the indirect immunofluorescence test. The differential kinetics of B-cell responses to PUU nucleocapsid vs. envelope proteins was emphasized further by the endpoint titres of IgG antibodies to N, G1 and G2 proteins in NE patients. The granular fluorescence correlated with low IgG avidity in 99.8%, and diffuse fluorescence with high avidity in 100% of 617 NE sera studied. Epitope scanning with overlapping 14-mer peptides covering the whole nucleocapsid protein by a shift of 3 amino acids revealed six major antigenic epitopes recognized by sera from acute-phase NE patients. The epitopes clustered mainly in the hydrophilic regions, and two of them in a highly variable region which could probably serve as an antigen to distinguish serologically between infections of closely related hantaviruses, some apparently apathogenic, some causing lethal infections. The anti-peptide epitope pattern varied between different individuals and a collection of several pin-bound peptides was needed to be recognised by most NE sera studied.

We have identified a synthetic peptide derived from the BZ-chain of mouse laminin, Arg-Asn-Ile-Ala-Glu-Ile-Ile-Lys-AspBe (p20), which simulates the neurite outgrowth-promoting activity of the native molecule. In organotypic cultures, neurons from newborn mouse brain or embryonic peripheral nervous system responded by extensive neurite outgrowth for native laminin or the peptide p20 in the culture medium. If rat cerebellar neurons were grown on laminin, l-5 FM (l-5 pg/ml) of peptide p20 in the culture medium competed with laminin and inhibited neuronal attachment and neurite outgrowth, whereas higher concentrations (> 50 FM; > 50 pg/ml) had a specific neurotoxic effect. When peptide p20 was used as the culture substratum, neurite outgrowth in cerebellar cultures was up to 60% of that seen on native laminin. Our results indicate that a neurite outgrowth-promoting domain of laminin is located in the a-helical region of the BZ-chain, and is active for both central and peripheral neurons.

Rhizobium etli CFN42 is a symbiotic nitrogen-fixing bacterium of the common bean Phaseolus vulgaris. The symbiotic plasmid p42d of R. etli comprises a gene encoding a putative (strept)avidin-like protein, named rhizavidin. The amino acid sequence identity of rhizavidin in relation to other known avidin-like proteins is 20-30%. The amino acid residues involved in the (strept)avidin-biotin interaction are well conserved in rhizavidin. The structural and functional properties of rhizavidin were carefully studied, and we found that rhizavidin shares characteristics with bradavidin, streptavidin and avidin. However, we found that it is the first naturally occurring dimeric protein in the avidin protein family, in contrast with tetrameric (strept)avidin and bradavidin. Moreover, it possesses a proline residue after a flexible loop (GGSG) in a position close to Trp-110 in avidin, which is an important biotin-binding residue. [3H]Biotin dissociation and ITC (isothermal titration calorimetry) experiments showed dimeric rhizavidin to be a high-affinity biotin-binding protein. Its thermal stability was lower than that of avidin; although similar to streptavidin, it was insensitive to proteinase K. The immunological cross-reactivity of rhizavidin was tested with human serum samples obtained from cancer patients exposed to (strept)avidin. No significant cross-reactivity was observed. The biodistribution of the protein was studied by SPECT (single-photon emission computed tomography) imaging in rats. Similarly to avidin, rhizavidin was observed to accumulate rapidly, mainly in the liver. Evidently, rhizavidin could be used as a complement to (strept)avidin in (strept)avidin-biotin technology.

Spermidine/spermine N 1 -acetyltransferase (SSAT), the rate-controlling enzyme in the interconversion of spermidine and spermine, is regulated by polyamines and their analogs at many levels of gene expression. Recently, SSAT pre-mRNA has been shown to undergo alternative splicing by inclusion of an exon that contains premature termination codons. In the present study, we show that alterations in the intracellular polyamine level resulted in a change in the relative abundance of SSAT transcripts. Addition of polyamines or their N-diethylated analogs reduced the amount of the variant transcript, whereas polyamine depletion by 2-difluoromethylornithine or MG-132 enhanced the exon inclusion. Experiments performed with protein synthesis inhibitors and siRNA-mediated down-regulation of Upf1 protein verified that the variant transcript was degraded by nonsensemediated mRNA decay (NMD). Interestingly, several proteins have been shown to regulate their expression by alternative splicing-coupled NMD, termed regulated unproductive splicing and translation (RUST). Our present results suggest that in the case of SSAT, RUST is mediated by polyamines, and this system functions to fine-tune the polyamine metabolism.