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Staphylococcal coagglutination, a rapid method of identifying infectious hematopoietic necrosis virus
1Laboratory for Fish Disease Research, Oregon State University, Corvallis 97331-3804.
Abstract:
A staphylococcal coagglutination test was developed for the rapid detection of infectious hematopoietic necrosis virus (IHNV) in cell cultures and infected fish. The test could be completed in 15 min but required a minimum IHNV titer of 10(6) PFU/ml to obtain a positive reaction. All IHNV isolates, representing the five electropherotypes taken from a wide variety of species and different geographic ranges, caused coagglutination of Staphylococcus aureus cells sensitized with rabbit polyclonal serum against the Round Butte IHNV isolate. The coagglutination reaction was blocked by preincubation of IHNV with homologous antiserum, and IHNV did not cause coagglutination of S. aureus cells sensitized with normal rabbit serum. In specificity tests, cells sensitized with rabbit anti-IHNV serum or normal serum did not coagglutinate in the presence of infectious pancreatic necrosis virus, viral hemorrhagic septicemia virus, cell culture medium components, or media from cultures of cell lines of salmonid and nonsalmonid origin. Most importantly, the coagglutination test was able to detect and identify IHNV directly from experimentally infected rainbow trout fry, the organs of naturally infected adult kokanee salmon and winter steelhead trout, and ovarian fluids of the winter steelhead trout. The coagglutination test is very suitable for field use, since it is inexpensive, simple to interpret, sensitive, and rapid and requires no specialized equipment.
Insights
A rapid staphylococcal coagglutination test accurately detects infectious hematopoietic necrosis virus (IHNV) in fish and cell cultures. This inexpensive, field-deployable method offers quick and reliable IHNV identification.
Area of Science:
- Aquatic Animal Health
- Virology
- Immunodiagnostics
Background:
- Infectious hematopoietic necrosis virus (IHNV) causes significant losses in salmonid aquaculture.
- Rapid and reliable diagnostic tools are crucial for managing IHNV outbreaks.
- Current detection methods can be time-consuming or require specialized equipment.
Purpose of the Study:
- To develop and validate a staphylococcal coagglutination test for rapid IHNV detection.
- To assess the test's sensitivity, specificity, and applicability in field conditions.
Main Methods:
- Development of a coagglutination test using Staphylococcus aureus sensitized with anti-IHNV rabbit polyclonal serum.
- Testing the assay with various IHNV isolates and other fish viruses.
- Evaluation of the test's performance on experimentally and naturally infected fish tissues and fluids.
Main Results:
- The coagglutination test detected IHNV in cell cultures and infected fish within 15 minutes.
- The test demonstrated high specificity, with no cross-reactivity with other tested viruses or cell culture components.
- IHNV was successfully identified directly from rainbow trout fry, kokanee salmon, and steelhead trout organs and ovarian fluids.
Conclusions:
- Staphylococcal coagglutination is a rapid, sensitive, and specific method for IHNV detection.
- The test is suitable for field applications due to its simplicity, low cost, and minimal equipment requirements.
- This assay provides a valuable tool for early detection and control of IHNV in aquaculture and wild fish populations.