No evidence of horizontal infection in horses kept in close contact with dogs experimentally infected with canine influenza A virus (H3N8)

Background

Since equine influenza A virus (H3N8) was transmitted to dogs in the United States in 2004, the causative virus, which is called canine influenza A virus (CIV), has become widespread in dogs. To date, it has remained unclear whether or not CIV-infected dogs could transmit CIV to horses. To address this, we tested whether or not close contact between horses and dogs experimentally infected with CIV would result in its interspecies transmission.

Methods

Three pairs of animals consisting of a dog inoculated with CIV (10^8.3 egg infectious dose₅₀/dog) and a healthy horse were kept together in individual stalls for 15 consecutive days. During the study, all the dogs and horses were clinically observed. Virus titres in nasal swab extracts and serological responses were also evaluated. In addition, all the animals were subjected to a gross pathological examination after euthanasia.

Results

All three dogs inoculated with CIV exhibited clinical signs including, pyrexia, cough, nasal discharge, virus shedding and seroconversion. Gross pathology revealed lung consolidations in all the dogs, and Streptococcus equi subsp. zooepidemicus was isolated from the lesions. Meanwhile, none of the paired horses showed any clinical signs, virus shedding or seroconversion. Moreover, gross pathology revealed no lesions in the respiratory tracts including the lungs of the horses.

Conclusions

These findings may indicate that a single dog infected with CIV is not sufficient to constitute a source of CIV infection in horses.     

Evaluation of right ventricular Tei index (index of myocardial performance) in healthy dogs and dogs with tricuspid regurgitation

Right ventricular (RV) Tei index (index of myocardial performance) has been demonstrated to be clinically useful in estimating RV function in various human cardiac diseases. The purposes of this study were to validate the correlation between RV Tei index and RV function obtained by cardiac catheterization in healthy dogs, and to evaluate the RV Tei index in dogs with tricuspid regurgitation (TR). In healthy dogs, the RV Tei index significantly correlated with the RV peak +dP/dt (r=-0.80, p<0.0001) and -dP/dt (r=0.69, p=0.0001). In normal dogs, the RV Tei index was not significantly correlated with heart rate, body weight, and age. The RV Tei index significantly increased in dogs with moderate to severe TR (0.39 +/- 0.35, p=0.0015), filariasis (0.46 +/- 0.16, p=0.0131), and trivial to mild TR and severe mitral regurgitation (MR; 0.61 +/- 0.14, p=0.0017) when compared with the normal dogs (0.17 +/- 0.10). In addition, the RV Tei index in dogs with TR significantly increased in association with pulmonary hypertension [PH(-), 0.19 +/- 0.09; PH(+), 0.65 +/- 0.14; respectively p<0.0001]. Our study has demonstrated that RV Tei index is a feasible approach to estimate RV function in dogs and is not influenced by heart rate, body weight, and aging. Further investigations are required to clarify the clinical significance of RV Tei index in dogs with right-sided cardiac diseases.     

Involvement of carbon catabolite repression on regulation of endopolygalacturonase gene expression in citrus fruit

 The Acpg1 gene of Alternaria citri encodes an extracellular endopolygalacturonase that is important for virulence in citrus fruits. Expression of Acpg1 is regulated by substrate induction and carbon catabolite repression. A green fluorescent protein (GFP) gene was employed as a reporter gene to define 813 bases upstream of the translation start site comprising the Acpg1 promoter. This upstream sequence contains five putative binding sequences of catabolite repressive element A (CreA), a cis-acting zinc finger repressor involved in carbon catabolite repression. We constructed each CreA-binding site-deleted Acpg1 promoters with GFP reporter gene and transformed them to A. citri. The construct PGPDL4 deleted from −401 to −813 showed both substrate induction and catabolite repression, whereas PGPDL5 additionally deleted from −1 to −84, including one putative CreA-binding site, resulted in a loss of catabolite repression function. Green fluorescence of PGPDL4 was induced by pectin in the peel but was repressed completely in the juice sac area of citrus fruit. However, green fluorescence of PGPDL5 was induced in both the peel and juice sac area, indicating that repression of Acpg1 in the juice sac area is likely accomplished by carbon catabolite repression. Received: October 4, 2002 / Accepted: October 31, 2002 Acknowledgments The authors thank Drs. D. Cullen, A. Van den Wymelenberg, and J. Andrews, University of Wisconsin, for providing pTEFEGFP containing GFP and Dr. T. Tsuge, Nagoya University, for providing transformation vector pSH75. The nucleotide sequence data of Acpg1 promoter region in the DDBJ, EMBL, and GenBank sequence databases is under accession number AB047543. This research was supported in part by grants to K.A. from the Ministry of Education, Culture, Sports, Science, and Technology of Japan.     

Potassium acetate-catalyzed acetylation of wood: extraordinarily rapid acetylation at 120°C

The catalytic effect of potassium acetate (KAc) on wood acetylation was investigated. Spruce wood specimens were impregnated with KAc and then heated in acetic anhydride at 120°C. The degree of acetylation was evaluated by the weight percent gain (WPG). In the presence of KAc, the reaction time to achieve a 20% WPG decreased by a factor of 200: 2 min was required in the KAc-catalyzed acetylation, while the uncatalyzed acetylation required at least 5 h. The hygroscopicity and dimensional stability of acetylated wood depended on the WPG irrespective of the treatment methods. This fact proved that KAc had no adverse influence on the dimensional stability of acetylated wood. As KAc is a cheap, water-soluble and non-toxic salt it can be a useful catalyst for the extraordinarily rapid acetylation of wood.     

Mechanical properties of wood in an unstable state due to temperature changes,and analysis of the relevant mechanism VI: dielectric relaxation of quenched wood

To analyze the effects of lignin on the destabilization of wood due to quenching, we examined the dielectric properties of untreated and delignified wood before and after quenching at 20°C from 50 Hz to 100 MHz. For untreated wood, the inflection points of log ε′ and log σ vs log f and the peak of log(tan δ) vs log f were attributed to interfacial polarization before quenching, and the location of the inflection point shifted to a higher frequency with increasing moisture content because of changes in the water cluster. After quenching, the inflection points of log ε′ and log σ and the peak of log(tan δ ) shifted to higher frequency; however, the values of log ε′, log σ recovered to those before quenching with the passage of time. For delignified wood, dielectric relaxation was observed at a higher frequency than for untreated wood irrespective of quenching. It was inferred that the mobility of water molecules was influenced by the cluster surroundings because of increased number of adsorption sites in hemicellulose. Moreover, after quenching, the recovery process did not change greatly over time; it was shown that the matrix structure was affected more by quenching with the loss of lignin.     

Purification of polygalacturonases produced by the pear scab pathogens, Venturia nashicola and Venturia pirina

An exopolygalacturonase and three endopolygalacturonases were purified from mycelia of pear scab pathogens, Venturia pirina and Venturia nashicola. The molecular weight of the isolated exoPG from V. pirina was 43 kDa, and the endoPGs from V. nashicola were 42 kDa as estimated by SDS–polyacrylamide gel electrophoresis. The pH optimum of the exoPG activity from V. pirina was 5.0. TheK_m and V_maxvalues of the exoPG were 0.08 mg ml⁻¹and 4.44 × 10⁻³ mmol reducing group min⁻¹ mg protein⁻¹. The N-terminal amino acid sequence of the exoPG from V. pirina was similar to that of the exoPG from Fusarium oxysporum f. sp. melonis, and the N-terminal amino acid sequences of the three endoPGs fromV. nashicola races 1, 2 and 3 were similar to other fungal endoPGs with a conserved motif of ASxxxTFTxAAAxxxG.     

Niche processes and conservation implications of fish community assembly in a rice irrigation system

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