Gontier C

β-propiolactone treatment impairs the biological activity of residual DNA from BHK-21 cells infected with rabies virus

The effects of beta-propiolactone (BPL), an alkylating and virus inactivating agent, on the structural and in vitro biological properties of different DNA preparations from BHK-21 cells were investigated. Both uninfected and rabies virus-infected cells were used. Purified cellular DNA (celDNA) was used as the reference, and supernatants from infected cells were treated with BPL. For structural and biological studies three types of DNA preparation were tested: celDNA; purified DNA from cell (infected or uninfected) supernatant (pcsDNA) with or without BPL treatment; and residual cell DNA present in purified rabies virus (inactivated or not) preparations. Rabies infection and BPL (diluted 1:4000) treatment induced modifications in the structure of the three DNA types, including strand breaks and nicks. The damage to the DNA structure by BPL modifies the biological properties of the pcsDNA appraised by its ability to serve as the template in vitro for different polymerases. When rabies virus was inactivated with BPL diluted 1:1000 the DNA damage increased dramatically: small double-stranded DNA fragments (50-200 base pairs) were generated which could not function as templates for polymerases.

A new immunostimulatory complex (PICKCa) in experimental rabies: antiviral and adjuvant effects

SummaryThe activity of an immunostimulatory complex (PICKCa) which is widely used against several human diseases in China was tested in experimental rabies prophylaxis. PICKCa protected mice against peripheral infection with both fixed and wild rabies strains. It also enhanced the protective activity of an experimental rabies vaccine injected either before or after rabies infection. PICKCa enhanced both non-specific immune responses and specific immunity including antibody production and cell mediated immunity as assessed by interleukin-2 production.

A modified rapid enzyme immunoassay for the detection of rabies and rabies-related viruses: RREID-lyssa

This paper presents a modification of the previously described Rapid Rabies Enzyme Immuno-Diagnosis test (RREID) by using biotinylated antibodies, streptavidin conjugate and a mixture of monospecific polyclonal antibodies against several lyssaviruses. In the modified technique (RREID-lyssa), microplates were sensitized with a mixture of purified antibodies against ribonucleoprotein (RNP) from Pasteur virus (Lyssavirus serotype 1), European Bat Lyssavirus (EBL, unclassified) and Mokola virus (Lyssavirus serotype 3). Bound RNP was detected by the same antibodies labelled with biotin and peroxidase-strepavidin conjugate. These techniques were used for the detection of RNP of different Lyssavirus serotypes (rabies and rabies-related viruses). For lyssavirus specimens of serotype 1, the threshold of detection of RREID and RREID-lyssa were similar. However, a smaller amount of labelled antibodies was needed when biotinylated antibodies were used. For specimens infected by rabies-related strains (serotypes 2, 3, 4 and EBL), the threshold of detection of the RREID-lyssa was between two and 512 times lower than with the RREID. The sensitivity and the specificity of the RREID-lyssa for rabies virus (serotype 1) when tested on a small field trial (53 specimens) were found to be identical to the RREID. Consequently, RREID-lyssa can be a useful tool for diagnostic laboratories that receive specimens infected by rabies-related viruses.

Rabies-specific production of interleukin-2 by peripheral blood lymphocytes from human rabies vaccinees

Cell-mediated immunity induced by rabies vaccination was studied in humans by the determination of specific interleukin-2 (IL-2) production in a large number of donors (postexposure immunized patients and pre-exposure immunized laboratory workers). Peripheral blood lymphocytes (PBL) from 35 donors were tested for IL-2 production after in vitro stimulation by different rabies and rabies-related viruses. IL-2 responses were compared to antibody recognition of these different virus serotypes by sera from the same individuals. IL-2 was produced by PBL from more than 85% of donors after stimulation with inactivated and purified rabies viruses (IPRV) prepared from either Pittman Moore (PM) or Pasteur Virus (PV) strains. IL-2 was also produced by 65 and 45% of donor PBL stimulated with IPRV from the European Bat Lyssavirus (EBL) and Mokola (Mok) rabies-related virus strains respectively. No correlation was found between the production of IL-2 by PBL and the levels of virus neutralizing antibody (VNAb). Moreover, 50, 25 and 35% of donors produced IL-2 after stimulation of their PBL with ribonucleoprotein (RNP) from PV-, EBL- and Mok-viruses, respectively. These results obtained with a large number of human rabies vaccinees and using an assay specific to T-cell activation confirm the significant cross-reactivity of T-cell responses directed against rabies and rabies-related viruses. This study shows that IL-2 production could be used for the study of cell-mediated immunity and T-cell memory induced in humans by rabies vaccination.