Confirmation of the efficacy of a novel formulation of metaflumizone plus amitraz for the treatment and control of fleas and ticks on dogs.

A novel spot-on formulation containing metaflumizone plus amitraz (ProMeris/ProMeris Duo for Dogs, Fort Dodge Animal Health, Overland Park, KS) was evaluated in four laboratory studies to confirm efficacy against fleas and ticks on dogs for 1 month. Three different strains of cat flea (Ctenocephalides felis felis) and four tick species were used. Rhipicephalus sanguineus and Dermacentor variabilis were evaluated concurrently in two studies and Ixodes scapularis and Amblyomma americanum in one study each. In all studies, dogs were randomly allocated to treatment groups and compared with nontreated dogs. One study also included a placebo treatment and a commercial product containing fipronil plus S-methoprene. All treatments were applied to the skin at a single spot between the scapulae on Day 0. Dogs were infested with fleas and/or ticks prior to treatment and then reinfested at weekly intervals for 6 weeks after treatment and evaluated for efficacy at 1 or 2 days after treatment and each reinfestation. These studies confirmed that treatment with ProMeris for Dogs at the proposed commercial dose rate rapidly controlled existing infestations of fleas and ticks on dogs. Treatment provided control of reinfesting fleas for up to 6 weeks and at least 4 weeks control of ticks. Efficacy was confirmed in a variety of dog breeds against three different flea strains and four common species of ticks found on dogs in the United States.

Effect of the 21-bp repeat upstream element on in vitro transcription from the early and late SV40 promoters.

The role of the 21-bp repeat region [simian virus 40 (SV40) coordinates 40-103] on early and late SV40 promoter functions has been investigated in vitro using a variety of mutated templates. Using either a HeLa whole cell extract or a S100 extract, we analyzed the transcripts by quantitative S1 nuclease mapping. GC-rich motifs contained in the 21-bp direct repeat constituted an essential element for efficient early transcription in vitro in agreement with previous in vivo results. These GC-rich motifs act in a non-polar fashion, since inversion of the 21-bp region did not reduce early transcription. Some point mutations in the 22-bp imperfectly repeated sequence, that drastically reduce initiations from the early promoter in vivo, had little effect in vitro, indicating that all the functions of these GC-rich motifs cannot be reproduced in vitro at present. The requirement for the 21-bp repeat region was less stringent when the concentration of the early promoter sequence was increased, which suggests that its function may be to facilitate the recognition of the 'weak' SV40 early TATA box. The multiple late start sites were accurately used in vitro and the GC-rich motifs contained in the 21-bp repeat region were an important element for efficient in vitro initiation of transcription from the late promoter, irrespective of their orientation. However, the effect of the 21-bp repeat region on late initiations decreased strikingly with increasing distance to the start sites, although it was still detectable over a distance of 220 bp. Under the present in vitro conditions, the 72-bp repeat region stimulates weakly both early and late transcription.