Interspecies transmission of equine influenza virus (H3N8) to dogs by close contact with experimentally infected horses

In horse populations, influenza A virus subtype H3N8 (equine influenza virus, EIV) is a very important pathogen that leads to acute respiratory disease. Recently, EIV has emerged in dogs, and has become widespread among the canine population in the United States. The interspecies transmission route had thus far remained unclear. Here, we tested whether the interspecies transmission of EIV to dogs could occur as a result of close contact with experimentally EIV-infected horses. Three pairs consisting of an EIV-infected horse and a healthy dog were kept together in individual stalls for 15 consecutive days. A subsequent hemagglutination inhibition test revealed that all three dogs exhibited seroconversion. Moreover, two of the three dogs exhibited virus shedding. However, the dogs exhibited no clinical signs throughout the course of the study. These data suggest that the interspecies transmission of EIV to dogs could occur as a result of close contact with EIV-infected horses without clinical symptoms. Although the interspecies transmission of EIV is unlikely to become an immediate threat to canine hygiene, close contact between EIV-infected horses and dogs should be avoided during an EI epidemic.     

Growth of bovine oocyte-granulosa cell complexes cultured individually in microdrops of various sizes

In mammalian embryo culture, the embryo:medium volume ratio can substantially affect embryo developmental performance. In the present study, we tested the possibility of improving the growth of bovine oocytes by reducing the medium volume, from a typical volume used in mouse follicle culture to a minimum possible level. A total of 282 complexes, each containing a growing oocyte 87-100 mum in diameter, were individually placed in microdrops of 2, 5, 10 or 20 microl and cultured for 13 days in a modified TCM-199 supplemented with 4% polyvinylpyrrolidone (molecular weight: 360 kDa). Oocyte diameter was measured every other day to trace the growth of each oocyte. Half the medium was replaced every other day or every day, and comparison revealed that daily replacement was more favorable for culture of these microdrops. The highest survival rate, 95%, occurred in the 20-microl microdrops, where most oocytes continued to grow throughout the culture period. In comparison, in the 5- and 10-microl microdrops, more oocytes died, and growth slowed towards the end of culture. In the 2-microl microdrops, which had the highest death rate, growth virtually ceased after 9 days. The surviving oocytes were usually accompanied by a characteristic dome-like structure of the granulosa cell mass, except in the 2-microl microdrops. In conclusion, the 20-microl microdrops allowed oocyte growth at an acceptable level, and any further reduction of the volume only had a negative impact on oocytes.     

Bovine leukemia virus high tax molecular clone experimentally induces leukemia/lymphoma in sheep

Sheep were inoculated with high tax coded pBLV-IF (H group, Nos.1-5) of bovine leukemia virus (BLV), wild tax coded pBLV-IF (W group, Nos. 6-11), or control plasmid (C group, Nos. 12-14). During the observation period (4 to 46 months), 5 of 5 cases in H group and 3 of 6 cases (Nos. 6, 7, 9) in W group became positive for gp 51. Only 1 case in H group became leukemic, and one case each of H and W groups developed lymphoma. In No. 3, lesions were found in multiple organs including the lymph nodes, gastrointestinal tract following abomasum, and heart. In No. 6, lesions of lymphoma were found only in the jejunum and heart. Morphologically, small to middle-sized lymphocytic neoplastic (NP) cells were found in both cases, but lymphoblastic NP cells were found only in No. 3. By immunohistochemical examination, the phenotypes of NP cells were determined as CD1-, CD4-, CD5- -, CD8alpha-, sIgM+, lambda light chain+, B-B4+, MHC class II+ in both case. The results of this study indicate that inoculation of pBLV-IF can induce lymphocytic and lymphoblastic leukemia/lymphoma in sheep. Additionally, it is suggested that the expression rate of tax gene is not associated with the development of leukemia/lymphoma in sheep experimentally inoculated with pBLV-IF.     

Effects of DDAVP administrated subcutaneously in dogs with aspirin-induced platelet dysfunction and hemostatic impairment due to chronic liver diseases

To evaluate the hemostatic effects of desmopressin (DDAVP) in dogs with aspirin-induced platelet dysfunction and hemostatic impairment in chronic liver diseases, 3 microg/kg DDAVP was administrated subcutaneously. In aspirin-induced platelet dysfunction dogs (n=5), prolonged BMBT (buccal mucosal bleeding time) was shortened significantly after DDAVP injection (2.2 +/- 1.2 min, P<0.05). In dogs with chronic liver diseases (n=4), activated partial thromboplastin time (APTT) tended to shorten by 0.9 to 3.0 sec, and prolonged BMBT was shortened in two cases for 4.2 and 1.7 min after DDAVP injection. Therefore, the present results indicated that DDAVP shortened the prolonged BMBT in dogs with aspirin-induced platelet dysfunction and chronic liver disease. DDAVP might be helpful in hemostasis under invasive procedures such as biopsy or surgery for dogs with hemostatic impairment.     

Amino Acid 129 of Cucumber mosaic virus Coat Protein Determines Local Symptom Expression and Systemic Movement in Tetragonia expansa, Momordica charantia and Physalis floridana

Local symptom expression and systemic movement of Cucumber mosaic virus (CMV) in Tetragonia expansa, Momordica charantia and Physalis floridana were mapped to the amino acid at position 129 of CMV coat protein (CP), using pseudorecombinants, chimeric RNAs, a site-directed mutant of RNA 3 and four strains of CMV : pepo-, SO-, MY17- and Y-CMV. Local and systemic symptoms caused by three strains, pepo-, SO- and MY17-CMV, and those by Y-CMV differed in the three host species. The three strains expressed local chlorotic spots at 24°C and systemic chlorotic spots and ringspots at 36°C, whereas Y-CMV developed local necrotic spots at 24°C but no systemic symptoms at 36°C in T. expansa. In M. charantia the three strains caused systemic chlorotic spots, whereas Y-CMV caused local necrotic spots. The three caused systemic mosaic and Y-CMV systemic necrosis in P. floridana. With pseudorecombinants combined with pepo- and Y-CMV RNAs, CMV RNA 3 was responsible for symptom expression and systemic infection. Inoculation with Y-CMV RNA 1, RNA 2 and chimeric RNA 3s exchanged CP gene fragments between pepo- and Y-CMV showed that NruI-XhoI fragment of CP was essential for symptom expression. Comparative analysis of the NruI-XhoI fragments revealed that only the amino acid at position 129 was common among the three strains but different from that of Y-CMV. Inoculation with a point mutant constructed by substituting one nucleotide resulting in an amino acid change from Ser to Pro at position 129 in Y-CMV CP verified the previous experiments. These results indicate that the amino acid at position 129 of CMV CP is the determinant for local symptom expression and systemic movement in the three host species. CMV CP containing Ser at position 129 may induce resistant responses in these plants. Received 29 June 2001/ Accepted in revised form 28 August 2001     

A Leafhopper (Hishimonus sellatus) Transmits Phylogenetically Distant Phytoplasmas: Rhus Yellows and Hovenia Witches' Broom Phytoplasma

Phytoplasmas causing a severe decline of three tree species, i.e., Rhus javanica, Hovenia tomentella and Zizyphus jujuba, in Japan were examined for their transmissibility by a leafhopper species Hishimonus sellatus, and for their phylogenetic relatedness. By H. sellatus, Rhus yellows (RhY) phytoplasma was transmissible to white clover and periwinkle seedlings, causing typical symptoms in these plants. Jujube witches' broom (JWB) phytoplasma was also transferred to the host plant, Z. jujuba, by the leafhopper. Because JWB phytoplasma was transmitted to Hovenia tomentella and caused the same symptoms as Hovenia witches' broom (HWB), JWB phytoplasma may be very closely related to HWB phytoplasma. RFLP analysis of the PCR products of 16S rDNA revealed that RhY phytoplasma belongs to the Aster yellows (AY) group, and JWB and HWB phytoplasmas belong to a different group (possibly Elm yellows group). Thus, we found that one species of leafhopper can carry phylogenetically distant phytoplasmas. Received 23 April 2001/ Accepted in revised form 29 October 2001     

KAv-1 is Better Suited to Chick Fibroblast Culture than DMEM or 199 Media

Cultured cells are a useful resource for poultry scientists, since these cells allow scientists to evaluate biological responses to conditions such as infectious diseases in vitro while mimicking the whole-body response in birds. However avian cell culture requires an optimized basal medium, and there are currently relatively few options for this basal medium (medium 199 and KAv-1). This means that there is still room for the development of an optimal basal medium for avian cell culture. Here we compare KAv-1 medium, Dulbecco''s modified Eagle medium (DMEM) and medium 199 during the culture of chick fibroblasts and determine that KAv-1 remains the optimal medium for these assays. Our results show that DNA damage is reduced in fibroblasts cultured in the KAv-1 medium, when compared to both DMEM and Medium 199 and that these cells also display improved growth dynamics in KAv-1 medium when compared to both DMEM and medium 199. To the best of our knowledge, this is the first study to describe a comparative analysis of culture media for avian cells, which would provide useful information for poultry scientists.     

Immunohistochemical analysis of the distribution of classical swine fever (CSF) viral antigen in boar-pig hybrids and pigs four weeks after infection

We detected the classical swine fever virus (CSFV) antigen in three boar-pig hybrids (hybrids) and three pigs. All animals were experimentally infected with CSFV strain JPN/27/2019 to optimize diagnostic sampling and risk assessment of virus dissemination. Two hybrids died 17- and 19-days post-inoculation (dpi). The other animals were euthanized at 28 dpi. The detection of CSFV antigen at 28 dpi in epithelial cells of the apocrine sweat and sebaceous glands in the skin, salivary glands, mucosal epithelial cells in the rectum, and epithelial cells in the kidney and urinary bladder, suggests that CSFV persists in these tissues and spreads via sweat, saliva, feces, and urine for at least 4 weeks. These findings reveal that hybrids and pigs represent a high risk of virus dissemination four weeks after infection with CSFV strain JPN/27/2019. Prominent CSFV antigens were also detected in hair follicles of the skin. These results suggest that postmortem sampling of animal skin may be effective for CSF diagnosis and can be used to develop a rapid and easy diagnostic method using hair follicles.     

Plasma concentrations of inhibin A in cattle with follicular cysts: relationships with turnover of follicular waves and plasma levels of gonadotropins and steroid hormones

We investigated the profiles of circulating levels of inhibin A and total inhibin in beef cows with follicular cysts in relation to the patterns of follicular development and circulating gonadotropins and steroid hormones. Turnover of follicular waves was monitored in five cows every 2 days for 70 days from 10 days after detection of estrus without ovulation. The mean interwave intervals were 19.6 ± 1.0 days (n = 18 waves with cysts from the five cows). Circulating levels of inhibin A were approximately 170 pg/ml before emergence of follicular waves with cysts and increased (P < 0.05) concomitantly with follicle emergence. High concentrations of inhibin A (greater than 300 pg/ml) were noted for 7 days during the growth phase of cystic follicles, but inhibin A levels decreased gradually when development of the cysts reached a plateau. This profile of inhibin A was similar to those of total inhibin and estradiol, but was inversely related to the changes in plasma FSH concentrations. LH pulse frequency and mean concentrations of LH in cows with cysts were higher than those observed in the luteal phase of normal cyclic cows. These results indicate that the capacity to secrete inhibin, as well as estradiol, is maintained in cystic follicles, the growth of which is extended by LH secretion at levels greater than those seen in the normal luteal phase. Inhibin A plays an important role in the extension of interwave intervals by suppressing recruitment of a new cohort of follicles.