Vibrio tubiashii has been linked to disease outbreaks in molluscan species, including
oysters, geoducks, and clams. In particular, oyster hatcheries in the Pacific Northwest
have been plagued by intermittent vibriosis since 2006. Accurate detection of vibrios,
including V. tubiashii, is critical to the hatcheries in order to allow for rapid
remediation efforts. The current methods for detection of Vibrio spp. are not ideal
for use at the hatchery. Plating samples require time and is not sensitive to extracelluar
pathogenic products, such as the secreted zinc-metalloprotease, VtpA. Other sensitive
methods to detect bacteria, such as qPCR, require a high level of laboratory skills
and expensive supplies that are prohibitive for use at hatchery sites. Thus, hatcheries
would benefit from a sensitive, simple method to detect V. tubiashii and its secreted
toxin. Here, we describe the development of two inexpensive and highly specific tests
for the shellfish-toxic zinc-metalloprotease secreted by V. tubiashii: enzyme-linked
immunoassays (ELISA) and a lateral flow immunoassay (dipstick assay). Both technologies
rely on a set of monoclonal antibodies used in a sandwich format, with the capture
antibody recognizing a different epitope than the detection antibody on the mature
VtpA protein. Both assays are quantitative and give colorimetric readouts. The sandwich
ELISA was sensitive when VtpA was diluted into PBS, but was markedly less sensitive
in conditions that correlate with the environment of hatchery-derived samples, such
as in the presence of seawater, algae, or oyster larvae. In contrast, the dipstick
assay remained very sensitive in the presence of these contaminants, is less work-intensive,
and much more rapid, making this format the preferred assay method for detecting VtpA
on site in a hatchery or environmental setting.