Medium-term cryopreservation of rabies virus samples.
BACKGROUND
The cryopreservation of rabies virus has been described in detail in the literature. To date, little information is available on the use of cryoprotective agents for cold preservation of this virus, and the available data focus only on short-term virus preservation. In this study, we investigated the medium-term cryopreservation of samples of rabies virus using different cryopreservation protocols.


METHODS
The cryopreservation protocols for the rabies virus samples were performed at -20°C and were divided according to the variables of time and cryoprotectant type used. The laboratory tests (intracerebral inoculation of mice, viral titration and direct immunofluorescence) were performed at regular intervals (360 and 720 days) to assess the viability of the viral samples according to the different preservation techniques used.


RESULTS
After 1 year of cryopreservation, the fluorescence intensity of intracellular corpuscles of the rabies virus and the median survival time of the mice differed between the positive controls and the treatments with the cryoprotectants. After 2 years, most of the samples subjected to the cryopreservation protocols (including the controls) did not produce fluorescence. However, the virus samples exposed to the cryoprotectant sucrose (68% solution) responded positively in the direct immunofluorescence assay and in the intracerebral inoculation of the mice.


CONCLUSIONS
Medium-term cryopreservation of the rabies virus inactivates the viral sample. However, the cryoprotectant agent sucrose (68%) produces a preservative effect in cryopreserved rabies virus samples.
Laboratório de Virologia, Universidade Estadual do Ceará, FortalezaCE.
Tereza D'ávila de Freitas
TD
Aguiar
Laboratório de Virologia, Universidade Estadual do Ceará, FortalezaCE.
Maria Fátima da Silva
MF
Teixeira
Lusofonia Afro-Brasileira, Universidade da Integração Internacional, RedençãoCE.
Edmara Chaves
EC
Costa
Laboratório de Virologia, Universidade Estadual do Ceará, FortalezaCE.
Allan Bezerra
AB
Vitaliano
Laboratório de Virologia, Universidade Estadual do Ceará, FortalezaCE.
Carlos Henrique de Andrade
CH
Teles
Laboratório de Virologia, Universidade Estadual do Ceará, FortalezaCE.
Igor Ciríaco
IC
Barroso
Laboratório de Virologia, Universidade Estadual do Ceará, FortalezaCE.
Ronaldo Pereira
RP
Dias
Laboratório de Virologia, Universidade Estadual do Ceará, FortalezaCE.
Nélio Batista de
NB
Moraes
D000818:Animals; D001921:Brain / Q000821:virology; D015925:Cryopreservation / Q000379:methods*; D003451:Cryoprotective Agents / Q000494:pharmacology*; D019085:Fluorescent Antibody Technique, Direct; D051379:Mice; D011820:Rabies virus / Q000187:drug effects / Q000502:physiology*
D003451:Cryoprotective Agents