Antiviral treatment of calves persistently infected with bovine viral diarrhoea virus.

BACKGROUND: Animals persistently infected (PI) with bovine viral diarrhoea virus (BVDV) are a key source of viral propagation within and among herds. Currently, no specific therapy exists to treat PI animals. The purpose of this research was to initiate evaluation of the pharmacokinetic and safety data of a novel antiviral agent in BVDV-free calves and to assess the antiviral efficacy of the same agent in PI calves. METHODS: One BVDV-free calf was treated with 2-(2-benzimidazolyl)-5-[4-(2-imidazolino)phenyl]furan dihydrochloride (DB772) once at a dose of 1.6 mg/kg intravenously and one BVDV-free calf was treated three times a day for 6 days at 9.5 mg/kg intravenously. Subsequently, four PI calves were treated intravenously with 12 mg/kg DB772 three times a day for 6 days and two PI control calves were treated with an equivalent volume of diluent only. RESULTS: Prior to antiviral treatment, the virus isolated from each calf was susceptible to DB772 in vitro. The antiviral treatment effectively inhibited virus for 14 days in one calf and at least 3 days in three calves. Subsequent virus isolated from the three calves was resistant to DB772 in vitro. No adverse effects of DB772 administration were detected. CONCLUSIONS: Results demonstrate that DB772 administration is safe and exhibits antiviral properties in PI calves while facilitating the rapid development of viral resistance to this novel therapeutic agent.

Tritrichomonas foetus infections in surveyed pet cats.

Tritrichomonas foetus is the causative agent of feline trichomoniasis, a large-bowel disease resulting in chronic diarrhea. Feline trichomoniasis has been reported in cats of both pure and mixed breeds and in both males and females. In order to estimate the prevalence of trichomoniasis in the pet cat population, we requested fecal samples, via veterinarians throughout the United States, from cats with or without clinical signs of trichomoniasis. Of the 173 feline fecal samples received from veterinarians, 17 were culture and PCR positive for T. foetus. Our results suggested no correlation between breed or sex and infection with T. foetus. All cats that were infected with T. foetus had diarrhea at the time the fecal sample was taken. Other enteric pathogens were present in nine of the 17 positive cats. Our results support that trichomoniasis is a disease of younger male and female cats of all breeds.

Prevalence of Anaplasma phagocytophilum in domestic felines in the United States.

Anaplasma phagocytophilum is among the more common tick-borne disease agents in the United States. It is of veterinary and public health significance as dogs, cats, and human beings are known to be susceptible. A. phagocytophilum is transmitted trans-stadially by either nymphs or adults of either the black-legged tick (Ixodes scapularis) or the western black-legged tick (Ixodes pacificus). Little information is available regarding either the prevalence of this agent in cats or the dynamics of vector transmission. Four hundred and sixty feline blood samples from sites throughout the United States were assayed for antibodies to A. phagocytophilum using an indirect immunofluorescence assay (IFA). Results of the prevalence study showed that 20 samples (4.3%) were positive for A. phagocytophilum antibodies by IFA at a 1:50 dilution, however these results could not be confirmed by PCR analysis. PCR analysis for other cross-reacting Ehrlichia/Anaplasma spp. was also negative. These results demonstrate that natural infection of A. phagocytophilum in cats is uncommon.

Phosphonoxins: rational design and discovery of a potent nucleotide anti-Giardia agent.

Phosphonoxins, a new class of synthetic, rationally designed anti-microbial agents, are described. From this class a sub-micromolar inhibitor of Giardia trophozoite growth has been identified.

Rational design and synthesis of novel nucleotide anti-Giardia agents.

Design and synthesis of a novel nucleotide anti-Giardia agent that is micromolar inhibitor of Giardia trophozoite growth in culture is described.

Hepatozoon spp.: pathological and partial 18S rRNA sequence analysis from three Brazilian dogs.

Molecular and histopathological studies were carried out on samples from three Brazilian dogs with persistent hepatozoonosis parasitemia. Canine hepatozoonosis was confirmed by finding gametocytes in blood smears. Histopathological examination of skeletal muscle biopsy revealed muscle degeneration and atrophy, and degenerating/regenerating myofibers, similar to the muscle degeneration caused by Hepatozoon americanum . However, the large cystic structures typical of H. americanum were not observed in muscle biopsies from these dogs. Partial 18S rRNA sequences amplified by PCR from the three Brazilian samples demonstrated closest similarity to the Hepatozoon sp. Fukuoka described in Japan (>99% identity). These results indicate that both additional clinical cases and genes need examination in order to determine the phylogenetic relatedness among canid Hepatozoon species.

Bovine viral diarrhea virus (BVDV) in cell lines used for somatic cell cloning.

Culture of cell lines from fetuses or postnatal animals is an essential part of somatic cell cloning. Fetal bovine serum (FBS) is commonly used in media for propagation of these cells. Unfortunately, bovine fetuses and postnatal animals as well as FBS are all possible sources of non-cytopathic bovine viral diarrhea virus (BVDV) which is widely distributed among cattle. This study was prompted when screening of samples sent to veterinary diagnostic labs revealed that 15 of 39 fetal fibroblast cell lines used in cloning research were positive for BVDV as determined by various assays including reverse transcription-polymerase chain reaction (RT-PCR). Goals of the research were to use both virus isolation and reverse transcription-nested polymerase chain reaction (RT-nPCR) to confirm which of the cell lines were actually infected with BVDV and to assay samples of media, FBS and the earliest available passages of each cell line in an attempt to determine the source of the viral infections. Sequence analysis of amplified cDNA from all isolates was performed to provide a definitive link between possible sources of virus and infected cell lines. Only 5 of the 39 cell lines were actually infected with BVDV. Three of these five lines were not infected at the earliest cryopreserved passage, leading to the conclusion that they likely became infected after culture in media containing contaminated FBS. In fact, sequence comparison of the amplified cDNA from one lot of FBS confirmed that it was the source of infection for one of these cell lines. Since BVDV was isolated from the remaining two cell lines at the earliest available passage, the fetuses from which they were established could not be ruled out as the source of the virus.

Use of imidacloprid-permethrin to prevent transmission of Anaplasma phagocytophilum from naturally infected Ixodes scapularis ticks to dogs.

One group of eight beagles was treated with a combination of imidacloprid and permethrin 7 days before exposure to Ixodes scapularis ticks that were naturally infected with Anaplasma phagocytophilum. A second group of eight beagles was not treated and was also exposed to infected ticks. Seven of eight non-treated dogs--but none of the treated dogs--developed specific antibodies to A. phagocytophilum. Results of this study indicate that a combination of imidacloprid and permethrin can prevent transmission of A. phagocytophilum to dogs if administered before exposure to infected ticks.

Prevention and elimination of bovine viral diarrhea virus infections in fetal fibroblast cells.

Noncytopathic infections with bovine viral diarrhea virus (BVDV) can compromise research and commercial use of cultured cells. The purpose of this research was to evaluate the ability of aromatic cationic compounds to prevent or treat BVDV infections in fetal fibroblast cell lines that are used in somatic cell nuclear transfer. To evaluate preventative use of compounds, 10 cell lines were inoculated with BVDV in the absence or presence of 2-(4-[2-imidazolinyl]phenyl)-5-(4-methoxyphenyl)furan (DB606), 2-(2-benzimidazolyl)-5-[4-(2-imidazolino)phenyl]furan dihydrochloride (DB772), or 2-(1-methyl-2-benzimidazolyl)-5-[4'-(2-imidazolino)-2'-methylphenyl]furan dihydrochloride (DB824). The 99% endpoints for prevention of viral replication by these treatments were 81, 6, and 14 nM. To evaluate therapeutic use of compounds, two fetal fibroblast cell lines infected with a genotype 1a strain of BVDV were cultured through four passages in the absence or presence of either 0.04 or 4 microM concentrations of DB772 or DB824. The presence and concentration of BVDV in media and cell lysates were evaluated using reverse transcription nested polymerase chain reaction and virus isolation from titrated sample. A single passage in 4 microM of either compound was sufficient to eliminate BVDV from cells without causing cytotoxicity. Our results demonstrate that in vitro infections with BVDV can be effectively prevented or eliminated by addition of aromatic cations.

The synthesis of dicationic extended bis-benzimidazoles.

The synthesis of extended dicationic bis-benzimidazoles starting from trans-1,2-bis(4-cyanophenyl)ethene and trans-1,2-bis(4-cyanophenyl)cyclopropane is reported. The target diamidines show significant in vitro activity against B. subtilis.

Detection of inhibition of bovine viral diarrhea virus by aromatic cationic molecules.

Bovine viral diarrhea virus (BVDV) is an economically significant pathogen of cattle and a problematic contaminant in the laboratory. BVDV is often used as an in vitro model for hepatitis C virus during drug discovery efforts. Aromatic dicationic molecules have exhibited inhibitory activity against several RNA viruses. Thus, the purpose of this research was to develop and apply a method for screening the aromatic cationic compounds for in vitro cytotoxicity and activity against a noncytopathic strain of BVDV. The screening method evaluated the concentration of BVDV in medium and cell lysates after 72 h of cell culture in the presence of either a 25 or 5 microM concentration of the test compound. Five of 93 screened compounds were selected for further determination of inhibitory (90 and 50%) and cytotoxic (50 and 10%) concentration endpoints. The screening method identified compounds that exhibited inhibition of BVDV at nanomolar concentrations while exhibiting no cytotoxicity at 25 microM concentrations. The leading compounds require further investigation to determine their mechanism of action, in vivo activity, and specific activity against hepatitis C virus.