Biomedical subjects
Publications and source records attributed to P E Ceccaldi.
In an attempt to improve the sensitivity of the rabies genome hybridization test, PCR amplification was used following reverse transcription of rabies RNA extracted from infected brain. Presence of amplified DNA is demonstrated with either cDNA synthesized from the antigenomic primer or from antimessenger primer.
The effect of colchicine, an inhibitor of axonal transport, on the spread of rabies virus in the central nervous system was investigated using Wistar rats. Colchicine was inoculated into the striatum at various times before and after inoculation of rabies virus into the same site. Rats were killed at various times after viral inoculation and the spread of rabies virus was monitored by rabies immunofluorescence of selected areas of brain. The most effective inhibitory effect was obtained by colchicine treatment applied two days before virus inoculation. Under these conditions, no fluorescent foci could be detected until day 3 post-infection whereas control rats exhibited infected cells as soon as two days post-infection. This inhibitory effect is reversible and the general consequence seems to be a delay in the rate of viral spread. However, five days after the virus challenge, some major brain areas were still partially preserved from infection (striatum, frontal cortex, pyriform cortex). Ten days after colchicine treatment, the microtubules have recovered their capacity to transport the virus. At the onset of paralysis, the general pattern of infection in brain sections from colchicine-treated rats was not significantly different from that of control rats. This inhibitory effect on the transport of rabies virus can be prolonged by administration of additional colchicine.
We have previously described the capacity of neurites extending from cultured rat sensory dorsal root ganglia (DRG) neurons to transport rabies virus through axoplasm in the retrograde direction. Here we report the infection of cultured neurons derived from the DRG and the subsequent anterograde transport of rabies virus from the infected cell somas through the extending neurites to its release into the culture supernatant. Viral transport was monitored by titration of the virus yield in the external compartment. Both early and late transport mechanisms of rabies virions were identified. The first one occurred a few hours post-infection and was undetectable 6 h later, before the initiation of viral replication. The velocity of this first wave of infective virions was in the range of 100 to 400 mm/day. The early viral transport was probably the result of a direct translocation of infective virions from the somatic site of entry to the neuritic extensions and subsequent release into the culture medium without replication in the cellular perikaryon. The second virus transport peak was detected 48 h post-infection. In this case, the virions detected in the neuritic compartment were presumably the progeny of the inoculated virus which had replicated in the perikaryon before the viral transport occurs. Using a four-compartment culture device we were able to demonstrate, simultaneously, retrograde and anterograde transport of the virus. The presence of antirabies serum in contact with the exposed neurites did not inhibit either the retrograde or the anterograde transport mechanisms. The viral release from the neuritic extensions after the fast anterograde transport was evaluated to be in the range of 150 to 300 infectious virions per bundle of neurites per day.