Medium-term cryopreservation of rabies virus samples

Introduction 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. .

Medium-term cryopreservation of rabies virus samples.

INTRODUCTION: 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.

Princípios básicos da criomicrobiologia: enfoque nos tipos de micro-organismos e nos principais agentes crioprotetores / Basic principles of criomicrobiologia: focus in kind of microorganisms and principals cryoprotectants agents

O reconhecimento da grande relevância da biodiversidade microbiana para o desenvolvimento humano tem conduzido ao aprimoramento de técnicas destinadas à conservação dos mais diversos espécimes microbiológicos. Contudo, ainda não existe uma fórmula singular, ideal ou universal que possibilite a eficiência da estocagem e preservação microbiana a longo prazo. Consequentemente, diversos micro-organismos para os quais há uma crescente demanda, ainda esperam pelo desenvolvimento de metodologias adequadas à sua conservação, fazendo da criobiologia um campo de vasto potencial para o desenvolvimento de pesquisas. Nesse contexto, a proposta dessa revisão é discutir os princípios básicos da criomicrobiologia, com enfoque na preservação dos variados tipos de micro-organismos e nos principais agentes crioprotetores, tomando como base estudos disponíveis na literatura científica.

The recognizing the great importance of microbial biodiversity for human development has led to the improvement of techniques for the conservation of diverse microbiological specimens. However, there isn't a singular, ideal or universal method to provice the efficiency of the long-term microorganisms stock and preservation. Many microorganisms for which there is a growing demand still wait for the development of satisfactory methodologies to their conservation, making the cryobiology a field of vast potential for the development of researches. Then, the proposal of this review is to discuss the basic principles of cryomicrobiology, focusing the preservation of kinds microorganisms and principals agents cryoprotectants, using the available studies in the comtemporary scientific literature as base.