Comparison of immunohistochemistry and polymerase chain reaction for detection of West Nile virus in naturally infected dead birds

Tejbir S Sandhu,Major S Dhillon,Dalbinder S Sidhu,Ying Fang

doi:10.3855/jidc.937

Abstract

Credible vector-borne disease surveillance programs, especially in developing countries with limited resources, must include diagnostic tests that are efficient, inexpensive and simple and safe to administer while maintaining high levels of sensitivity and specificity. Since immunohistochemistry (IHC) includes most of these features, its sensitivity, specificity, predictive positive value (PPV) and predictive negative value (PNV) for West Nile virus (WNv) screening were compared to those of the gold standard, RT-PCR testing of kidney tissue in dead birds. IHC and RT-PCR were performed for WNv antigen on 41 dead birds (belonging to five orders) collected from the northwest region of the Riverside County of California. Fixed tissue sections were screened by IHC using polyclonal antibodies, and frozen kidney tissues were tested with RT-PCR. Kidney screening with IHC showed sensitivity, specificity, PPV and NPV of 95.45%, 73.68%, 80.77% and 93.33%, respectively. Based on WNv screening of kidney tissue, IHC and RT-PCR were in agreement with 95.45% (21/22) for positive dead birds and were in 100% (22/22) agreement when multi-organ screening by IHC was performed. The present study showed that IHC is as equally effective as RT-PCR in screening for WNv in dead birds. Therefore, IHC can effectively serve as a competent screening technique for those disease surveillance agencies that lack expensive RT-PCR technology while promoting safer biohazardous conditions, except at the initial stage of tissue collection.

Highlights

Credible vector-borne disease surveillance programs, especially in developing countries with limited resources, must include diagnostic tests that are efficient, inexpensive and simple and safe to administer while maintaining high levels of sensitivity and specificity
Based on kidney tissue testing of these 41 birds, IHC had a sensitivity of 95.45% and specificity of 73.68% with predictive positive value (PPV) of 80.77% and predictive negative value (PNV) of 93.33% (Table 1)
The relationship between reverse transcriptase polymerase chain reaction (RT-PCR) and IHC for West Nile virus (WNv)-positive birds was 95.45% (21/22), and increased to 100% (22/22) when multiple organs from the same bird were screened with IHC

Summary

Introduction

Credible vector-borne disease surveillance programs, especially in developing countries with limited resources, must include diagnostic tests that are efficient, inexpensive and simple and safe to administer while maintaining high levels of sensitivity and specificity. Since immunohistochemistry (IHC) includes most of these features, its sensitivity, specificity, predictive positive value (PPV) and predictive negative value (PNV) for West Nile virus (WNv) screening were compared to those of the gold standard, RT-PCR testing of kidney tissue in dead birds. Based on WNv screening of kidney tissue, IHC and RT-PCR were in agreement with 95.45% (21/22) for positive dead birds and were in 100% (22/22) agreement when multi-organ screening by IHC was performed. Conclusions: The present study showed that IHC is as effective as RT-PCR in screening for WNv in dead birds. In California, USA, it is a common practice to conduct WNv testing of dead birds with reverse transcriptase polymerase chain reaction (RT-PCR) by screening kidney tissue [2]. Similar to PCR, immunohistochemistry (IHC) is a powerful diagnostic technique for WNv screening

Methods

Results

Conclusion