Isolates of Helicobacter pylori from 88 patients were characterised by cagA status, cagA pathogenicity island (PAI) right-end motifs, iceA, vacA and lspA-glmM genotypes, primarily by PCR-based analysis, to investigate whether Argentinean isolates differed from those recovered in southern Europe or other Latin American countries. PCR-based analysis of vacA alleles was confirmed by reverse hybridisation in 56 cases, while sequence analysis was performed either when iceA and vacA genotypes could not be determined by PCR, or to investigate PCR and reverse hybridisation vacA genotyping discordance. Typing by lspA-glmM restriction fragment length polymorphism was performed with HhaI and AluI. The pattern of cag PAI right-end motifs and the prevalence of type Ia were similar to those in isolates from southern European countries, with cagA(+)/iceA1/vacA-s1 m1 being the commonest genotype. Reverse hybridisation identified a vacA-s1a/s1b recombinant allele, confirmed by sequencing analysis. Analysis of lspA-glmM genotypes identified at least 73 unrelated strains. Few mixed infections were identified, but in one case, isolates from a single biopsy exhibiting two vacA alleles were shown by lspA-glmM fingerprints to be two unrelated strains. No associated effect on ulcer disease risk was demonstrated by analysis of cagA, vacA and iceA status. Overall, the isolates of H. pylori from Argentina were similar to isolates from southern Europe or Latin American countries, and infections were associated mainly with single H. pylori strains.

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SUMMARYA new inactivation process for foot-and-mouth disease virus (FMDV) has been developed. This process is based on the activation of the FMDV endonuclease by incubation of unfractionated viral suspension or purified virions at 37 °C in the presence of high concentrations of monovalent cations such as K +, Cs + or NH2 at pH 8.5. This procedure completely inactivated several FMDV vaccine strains yielding preparations having similar amounts of 140S particles to untreated controls. The inactivation followed first-order kinetics and the rate of inactivation was faster than that achieved with other agents, e.g. binary ethyleneimine. Testing in suckling mice or tissue culture revealed no residual infectivity after inactivation. Virus particles purified from inactivated preparations showed (i) the same sedimentation coefficient as noninactivated preparations, (ii) electrophoretic patterns of their viral capsid proteins identical to those derived from non-inactivated preparations, and (iii) extensive degradation of the 35S viral RNA. This method is safer than inactivation with aziridines because only innocuous chemicals are used in the process.

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