Approaches for the Development of Rapid Serological Assays for Surveillance and Diagnosis of Infections Caused by Zoonotic Flaviviruses of the Japanese Encephalitis Virus Serocomplex

Table 1

Comparison of commonly used serological assays for the diagnosis of JEV serocomplex flaviviral infections.

Assay	Differentiation between IgM and IgG	Time to run assay	Handling of live virus by the end user	Species specific?^#	Sensitivity*	Specificity*	High throughput	Target flaviviral protein for serum antibodies	Commercialised or available from government Agencies?
PRNT	No, but an increased titre using paired sera is indicative of a recent infection	Days	Yes	No	High.; It is the gold standard assay	High.; It is the gold standard assay, but requires the simultaneous testing of endemic flaviviruses	No	Neutralising epitopes of the E protein	No
HI	No, but an increased titre using paired sera is indicative of a recent infection	Hours	No once the antigen has been prepared	No	High	Low. Requires the simultaneous testing of endemic flaviviruses	No	E protein	No
IFA	Yes	Hours	No once the slides have been prepared	Yes	Moderate, for example, IgM IFA not as sensitive as ELISA [128, 129].	IgM: Moderate, for example, cross-reactivity 17% [130]; 14% [128]; IgG: Low, for example, cross-reactivity: 63% [130]; 45% [128]	No	All	Yes, for example, Focus Diagnostics and Scimedx
ELISA IgG/IgM	Yes	Hours	No	Yes	High, for example, Focus Diagnostics WNV DxSelect IgM: 93–100% [131]	IgM: Moderate to High, for example, Focus Diagnostics WNV DxSelect IgM: 100% [131], but cross-reactivity with some cases of other flaviviral infections [132]	Yes	E protein	Yes, for example, Focus Diagnostics, Panbio, CDC
Blocking/ Competitive	No	Hours	No	No	High, for example, [58]	High, for example, [47]	Yes	E or NS1	No, but mAbs can be purchased from Millipore.
Immunoblot using whole viral antigen	Yes	Hours	No	Yes	Moderate, for example, [94]	Depends on the protein targeted, for example, [94]	No	E, prM and NS1	No
Lateral Flow	IgM only	Minutes	No	Yes	High 98.8% [133]	High 95.3% [133]	No	E protein	Yes, for example,; RapidWN [133]
MIA	Yes	Hours	No	Yes	High	Moderate, for example, high specificity for known negative samples, but some cross-reactivity with other flaviviruses [134] High specificity for NS5 MIA [63]	Yes	E protein [135]; NS5 [63]	Yes

^#Is the assay normally set up to be specific for the species being tested, for example, horse, human, and so forth?
*The sensitivity and specificity of the assays depends on the standard to which they were compared.