A prognostic score for postherpetic neuralgia in ambulatory patients.

The main objective was to develop a scoring system for easy use by the physician in daily clinical practice in deciding the appropriate treatment for his herpes zoster patient. Data from 635 patients who did not receive antiviral therapy were included in this analysis. Of these, 131 developed postherpetic neuralgia (PHN). Of the 29 variables tested univariately in this study, 15 showed a significant correlation with the incidence of PHN, but only six proved to contribute to the overall predictive power in the multivariate approach. Using two independent approaches, the model showed a very satisfactory performance in the validation sample. Patients without acute pain rarely developed PHN. In those with acute pain, being female, being over 50 years of age, having more than 50 lesions, having lesions of a hemorrhagic nature, having cranial or sacral localisation of the rash or having pain in the prodromal phase proved to be significant, multivariate factors. An easy-to-use scoring system used in a risk graph is proposed. These data should be useful in the individual treatment decision as well as in the design and analysis of therapeutic trials in herpes zoster.

Characterization of the N-terminal part of the neutralizing antigenic site I of coxsackievirus B4 by mutation analysis of antigen chimeras.

Coxsackievirus B3 (CVB3) as a potential RNA virus vector for the presentation of foreign antigenic epitopes was further characterized. Insertion mutagenesis of infectious CVB3 cDNA yielded viable antigen chimeras containing variant BC loops of VP1 of coxsackievirus B4 (CVB4). Analysis of three antigen chimeras allowed the mapping of the N-terminal part of the neutralizing antigenic site 1 (N-Ag1) of CVB4 which is located in the BC loop of the structural protein VP1. A significant neutralization of a viable chimera with the deletion of CVB4-specific amino acid Ser-83 at the amino terminus of the VP1 BC loop was obtained with CVB4 serotype-specific polyclonal antisera. This neutralization was reduced after further deletion of the adjacent Ala-84, suggesting that this amino acid either constitutes the beginning of N-Ag1 of CVB4 or is essential for the conformation of the adjacent epitope. In contrast, exchange of amino acid Ser-86 to alanine, in the middle of the BC loop, led to complete loss of reactivity with CVB4-specific antibodies, demonstrating the importance of this residue for binding of CVB4 neutralizing antisera. Furthermore, we observed that manipulations of the VP1 BC loop resulted in increased thermolability of the viable chimeras in comparison to CVB3, although replication efficiencies were similar.

Mapping of a neutralizing antigenic site of Coxsackievirus B4 by construction of an antigen chimera.

A neutralizing antigenic site of coxsackievirus B4 (CVB4) was identified by construction of an antigen chimera between coxsackievirus B3 (CVB3) and CVB4. This chimera, designated CVB3/4, was constructed by inserting five amino acids of the putative BC loop of the structural protein VP1 of CVB4 into the corresponding loop of CVB3 by site-directed mutagenesis of infectious recombinant CVB3 cDNA. The chimeric cDNA was capable of inducing an infectious cycle upon transfection of permissive host cells. The resulting chimeric virus CVB3/4 was neutralized and precipitated by CVB4 and CVB3 serotype-specific polyclonal antisera, demonstrating that it unifies antigenic properties of both coxsackievirus serotypes. In addition, the chimera elicited antibodies in rabbits which were capable of neutralizing the two coxsackievirus serotypes CVB3 and CVB4. The insertion of the CVB4-specific antigenic site into the BC loop of CVB3 reduces the efficiency of viral replication, resulting in a small-plaque morphology of the virus chimera. In summary, these data give evidence for the presence of a serotype-specific neutralizing antigenic site in the BC loop of VP1 of CVB4 (amino acids 81 to 89). Our findings suggest that the construction of intertypic chimeras can be used as a tool for the identification of antigenic sites of coxsackieviruses. The retained immunogenicity of the mapped CVB4-specific antigenic epitope, when expressed in CVB3, indicates that CVB3 can be used as a RNA virus vector for heterologous antigenic sites.

Reassortment of pilin genes in Neisseria gonorrhoeae occurs by two distinct mechanisms.

Phase and antigenic variation of pilin expression in Neisseria gonorrhoeae result from recombination events in which variant sequences from one of the silent loci (pilS) are transferred to the expression locus (pilE). Such rearrangements were originally thought to be gene conversions, but findings showing that phase variation is partially inhibited by DNase I, that piliated (P+) cells are highly competent for DNA uptake and that gonococci readily undergo autolysis in culture, led to the suggestion that pilin variation occurs through transformation by exogenous DNA. We have developed a simple method for the selection of non-piliated (P-) cells and have evaluated naturally occurring P+ to P- transitions. Two primary pathways of pilin variation can be distinguished--transformation-mediated recombination, which is influenced by culture conditions and inhibited by DNase I, and intragenomic reciprocal recombination, which is unaffected by DNase I. Furthermore, we demonstrate that both piliated and revertible P- cells are competent for DNA uptake, an essential prerequisite of the first pathway.