BMBL Section VII

Biosafety Documents

BMBL Table of Contents

Arboviruses Assigned to Biosafety Level 2

The American Committee on Arthropod-Borne Viruses (ACAV) registered 537 arboviruses as of December 1997. In 1979, the ACAV's Subcommittee on Arbovirus Laboratory Safety (SALS) categorized each of the 424 viruses then registered in the Catalogue of Arboviruses and Certain Other Viruses of Vertebrates⁽¹⁾ into one of four groups of recommended practices, safety equipment, and facilities. These are described in this publication as Biosafety Levels 1-4.⁽²⁾ SALS has periodically updated the 1980 publication by providing a supplemental listing and recommended levels of practice and containment for arboviruses registered since 1979.

SALS categorizations are based on risk assessments derived from information provided by a worldwide survey of 585 laboratories working with arboviruses. SALS recommends that work with the majority of these agents be conducted at the equivalent of Biosafety Level 2 (Table 1). SALS also recognizes five commonly used vaccine strains for which attenuation is firmly established. These viruses may be handled safely at BSL-2 provided that personnel working with these vaccine strains are immunized (Table 2). SALS has classified all registered viruses for which insufficient laboratory experience exists as BSL-3 (Table 3), and reevaluates the classification whenever additional experience is reported.

The viruses classified as BSL-2 are listed alphabetically in Table 1 on pages 186 through 188 and include the following agents that are reported to have caused laboratory-associated infections.^(3)(4)(5)

Table 1

* Export license required by Department of Commerce

** An importation or domestic transfer permit for this agent can be obtained from USDA/APHIS/VS.

The results of the SALS survey clearly indicate that the suspected source of the laboratory-associated infections listed above was other than exposure to infectious aerosols. The recommendation that work with the 342 arboviruses listed in Table 1 be conducted at Biosafety Level 2 was based on the existence of adequate historical laboratory experience to assess the risks when working with this group of viruses risks. This indicates that either (a) no overt laboratory-associated infections are reported; (b) infections resulted from exposures other than to infectious aerosols; or © if disease from aerosol exposure is documented, it is uncommon.

Laboratory Hazards: Agents listed in this group may be present in blood, CSF, central nervous system and other tissues, and infected arthropods, depending on the agent and the stage of infection. The primary laboratory hazards are posed by accidental parenteral inoculation, contact of the virus with broken skin or mucous membranes, and bites of infected laboratory rodents or arthropods. However, infectious aerosols may also be a potential source of infection.

Recommended Precautions: Biosafety Level 2 practices, safety equipment, and facilities are recommended for activities with potential infectious clinical materials and arthropods and for manipulations of infected tissue cultures, embryonate eggs, and rodents. Infection of newly hatched chickens with eastern and western equine encephalomyelitis viruses is especially hazardous and should be undertaken only by immunized personnel under Biosafety Level 3 conditions. Investigational vaccines (IND) against eastern equine encephalomyelitis and western equine encephalomyelitis viruses are available through the Centers for Disease Control and Prevention (telephone 404-639-3356) and the U.S. Army Medical Research Institute for Infectious Diseases, (USAMRIID) Fort Detrick, Maryland (telephone 301-619-2833). The use of these vaccines is recommended for personnel who work directly and regularly with these two agents in the laboratory.

Prior to 1988, 12 laboratory-acquired dengue infections were reported. However, from 1988 through 1991, four additional cases have been documented. In all four cases, proper protective gear (long-sleeved lab gowns tying in back, gloves, masks, safety glasses) was not worn, and in three instances, containment of potential aerosols in a laminar flow biosafety cabinet was ignored. These aerosols or infected fluids most likely contaminated broken, unprotected skin. An additional factor in these cases was work with highly concentrated amounts of virus. Safe manipulation of dengue viruses in the laboratory (particularly in concentrated preparations) requires strict adherence to Biosafety Level 2 recommendations.

Large quantities and/or high concentrations of any virus have the potential to overwhelm both natural immune mechanisms and vaccine-induced immunity. When a virus from Biosafety Level 2 is being produced in large quantities or in high concentrations, laboratory directors should ensure that proper protective gear is utilized, as described in the above paragraph, and that manipulations are performed in laminar flow biosafety cabinets. (See also Section V, Risk Assessment.)

Transfer of Agents: For a permit to import this agent, contact CDC. Laboratory registration with CDC is required before sending or receiving these select agents.

References

1. International Catalog of Arboviruses Including Certain Other Viruses of Vertebrates. 1985. The Subcommittee on Information Exchange of the American Committee on Arthropod-borne Viruses. Third Edition. N. Karabatsos, Editor. American Society for Tropical Medicine and Hygiene. San Antonio, TX.

2. Subcommittee on Arbovirus Laboratory Safety for Arboviruses and Certain Other Viruses of Vertebrates. 1980. Am J Trop Med Hyg 29(6):1359-1381.

3. Hanson, R.P., et al. 1967. Arbovirus infections of laboratory workers. Science 158:1283-1286.

4. Pike, R.M. 1976. Laboratory-associated infections: Summary and analysis of 3,921 cases. Hlth Lab Sci 13:105-114.

5. Subcommittee on Arbovirus Laboratory Safety for Arboviruses and Certain Other Viruses of Vertebrates. 1980. (2)

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