A Cost‐Effective One‐Step PCR Assay Used to Determine the Occurrence of White Spot Syndrome Virus ( WSSV ) in Wild Shrimp Along the Mozambican Coast

This study reports the optimization of a cost-effective one-step PCR assay for the detection of White Spot Syndrome Virus (WSSV) in wild shrimp populations, providing an accessible alternative to expensive commercial nested PCR kits in Mozambique. Primer sets targeting VP19, VP24, VP26 and VP28 were evaluated, with the VP28_2 primer set demonstrating the highest sensitivity and no cross-reactivity with Infectious Hypodermal and Haematopoietic Necrosis Virus (IHHNV) or Decapod Iridescent Virus 1 (DIV1). Cost analysis showed that the optimized assay is approximately three times less expensive than commercial nested PCR (USD 5.57 vs. USD 15.75 per reaction). The assay was applied to 300 wild shrimp specimens (Penaeus indicus and Penaeus monodon) collected during a cross-sectional survey conducted in the rainy season (October-November 2022) at 15 landing sites across six provinces. WSSV was detected in 60.7% of samples, with significant regional variation: 78.0% in the South, 58.0% in the Centre and 48.1% in the North. Although the findings indicate widespread WSSV occurrence in wild shrimp populations, the cross-sectional design, single-season sampling and sample size limit inference on temporal trends. Nevertheless, the optimized assay provides a practical and affordable tool for routine WSSV surveillance under existing resource constraints.