Evaluation and Significance of Tetracycline Stability in Rabies Vaccine Baits

Abstract

Tetracycline is widely used as a biomarker for bait consumption by wildlife; tetracycline is incorporated into bones and teeth and can be detected by fluorescence microscopy several weeks postconsumption. During 2003, the United States Department of Agriculture distributed more than 10 million tetracycline-containing rabies-vaccine baits to control the spread of wildlife vectored rabies to humans, pets, and livestock. To estimate the percentage of target species consuming the baits, raccoons and skunks were collected in baited areas and teeth were analyzed for the presence of the biomarker. Several incidents of low biomarker detection rates prompted an investigation of the stability of the biomarker in the baits. Baits were collected at several points along the manufacturing and distribution chain. Baits were analyzed for free and polymer-bound tetracycline and the less active isomer epitetracycline. Results indicated that a portion of the tetracycline was converted to epitetracycline. Additionally, significant quantities of both compounds were trapped in the polymer, which is homogeneously distributed throughout the bait. The results of this study suggest that approximately 40% of the target quantity of tetracycline was unavailable for absorption. This situation could contribute to low biomarker detection rates and suggests that formulation modification should be considered.

Oral Rabies Vaccination Variation in Tetracycline Biomarking Among Ohio Raccoons

“…Tetracycline hydrochloride (tetracycline) is a commonly used compound for this purpose, and is detectable 2-5 days postconsumption (Hanlon et al, 1989) by ultraviolet microscopy of crosssectioned teeth . Consequently, tetracycline has an extensive history of use in oral vaccination and predator control (Linhart and Kenelly, 1967;Hanlon et al, 1989;Bachmann et al, 1990;Hable et al, 1992;Creekmore et al, 1994;Farry et al, 1998;Johnston et al, 2005;Slate et al, 2005;Ramey et al, 2008;Rosatte et al, 2008). More specifically, tetracycline has been used to assess bait uptake as part of oral vaccination campaigns and research in red foxes (Vulpes vulpes; Johnston and Voight, 1982;Niin et al, 2008), striped skunks (Mephitis mephitis; Johnston and Voight, 1982), raccoons (Procyon lotor; Rupprecht et al, 1987;Rosatte et al, 2009), coyotes (Canis latrans; Linhart and Kinelly, 1967), raccoon dogs (Nyctereutes procyonoides; Niin et al, 2008), and feral swine (Sus scrofa; Campbell et al, 2011).…”

Effect of Tooth Removal on Recaptures of Raccoons

“…), wolves (Canis lupus), mink (Mustela vison), sea otters (Enhydra lutris), and fisher (Martes pennanti; Arthur et al 1992, Bodkin et al 1997, Landon et al 1998, Whitman 2003, Costello et al 2004). In particular, premolar extractions are regularly used in studies of raccoons (Procyon lotor), both for the determination of age (Johnson 1970, Nixon et al 2001, Totton et al 2004) and to monitor the consumption of rabies vaccine-laden baits through tetracycline biomarkers (Olson et al 2000, Johnston et al 2005. However, raccoons are capable of long-term memory (Elder andNissen 1933, Kitzmiller 1934) and, thus, any pain or negative stimuli associated with a tooth extraction could negatively influence the probability of recapturing individuals during subsequent days or trapping occasions.…”

Rational design of rabies vaccine formulation for enhanced stability

“…Reports regarding variation of solution conditions and lyophilization are limited. Although various conditions perturbing the stability of the rabies virus have been described briefly (14,18,(22)(23)(24), the underlying mechanism of degradation is not yet understood, as is often the case for viruses.…”