Diagnostic Testing

SLE virus is difficult to isolate from clinical samples and almost all isolates have come from brain tissue or cerebrospinal fluid (CSF). In the absence of a sensitive and non-invasive virus detection method, serologic testing is the primary method for diagnosing SLEV infection. All SLEV disease cases should be reported to local public health authorities.

Antibody Testing

Laboratory diagnosis is generally accomplished by testing of serum or CSF to detect SLE virus-specific IgM and neutralizing antibodies. Immunoassays for SLE virus IgM antibodies are available commercially and through state public health laboratories and CDC. Initial serological testing is performed using IgM capture enzyme-linked immunosorbent assay (ELISA). Because of potential cross-reactivity to other flavivirus infections (e.g., West Nile virus, Powassan virus) or non-specific reactivity, a positive SLE virus IgM antibody test result should be confirmed by neutralizing antibody testing (plaque-reduction neutralization test [PRNT]) of serum specimens at a state public health laboratory or CDC.

Other Tests

Viral cultures and tests to detect viral RNA (e.g., reverse transcriptase-polymerase chain reaction [RT-PCR]) can be performed on serum, CSF, and tissue specimens that are collected early in the course of illness and, if results are positive, can confirm an infection. Immunohistochemistry (IHC) can detect SLE virus antigen in formalin-fixed tissue. Negative results of these tests do not rule out SLE virus infection. Viral culture, RT-PCR, and IHC can be requested through state public health laboratories or CDC.

Additional Information

Contact your state or local health department for assistance with diagnostic testing. They can assist you with determining if samples should be sent to the CDC Arbovirus Diagnostic Laboratory for further testing.

ALL RESULTS WILL BE SENT TO THE APPROPRIATE STATE HEALTH DEPARTMENT. Specimens should be submitted to CDC through state health departments.