The immune response and maternal antibody interference to a heterologous H1N1 swine influenza virus infection following vaccination

This study investigated the efficacy of a bivalent swine influenza virus (SIV) vaccine in piglets challenged with a heterologous H1N1 SIV isolate. The ability of maternally derived antibodies (MDA) to provide protection against a heterologous challenge and the impact MDA have on vaccine efficacy were also evaluated. Forty-eight MDA(+) pigs and 48 MDA(-) pigs were assigned to 8 different groups. Vaccinated pigs received two doses of a bivalent SIV vaccine at 3 and 5 weeks of age. The infected pigs were challenged at 7 weeks of age with an H1N1 SIV strain heterologous to the H1N1 vaccine strain. Clinical signs, rectal temperature, macroscopic and microscopic lesions, virus excretion, serum and local antibody responses, and influenza-specific T-cell responses were measured. The bivalent SIV vaccine induced a high serum hemagglutination-inhibition (HI) antibody titer against the vaccine virus, but antibodies cross-reacted at a lower level to the challenge virus. This study determined that low serum HI antibodies to a challenge virus induced by vaccination with a heterologous virus provided protection demonstrated by clinical protection and reduced pneumonia and viral excretion. The vaccine was able to prime the local SIV-specific antibody response in the lower respiratory tract as well as inducing a systemic SIV-specific memory T-cell response. MDA alone were capable of suppressing fever subsequent to infection, but other parameters showed reduced protection against infection compared to vaccination. The presence of MDA at vaccination negatively impacted vaccine efficacy as fever and clinical signs were prolonged, and unexpectedly, SIV-induced pneumonia was increased compared to pigs vaccinated in the absence of MDA. MDA also suppressed the serum antibody response and the induction of SIV-specific memory T-cells following vaccination. The results of this study question the effectiveness of the current practice of generating increased MDA levels through sow vaccination in protecting piglets against disease.     

Effects of extrathoracic airway obstruction on intrathoracic pressure and pulmonary artery pressure in exercising horses

OBJECTIVE: To determine whether dorsal displacement of the soft palate (DDSP) results in pulmonary artery hypertension and leads to increases in transmural pulmonary artery pressure (TPAP); to determine whether pulmonary hypertension can be prevented by prior administration of furosemide; and to determine whether tracheostomy reduces pulmonary hypertension. ANIMALS: 7 healthy horses. PROCEDURE: Horses were subjected to 3 conditions (control conditions, conditions after induction of DDSP, and conditions after tracheostomy). Horses were evaluated during exercise after being given saline (0.9% NaCl) solution or furosemide. RESULTS: Controlling for drug, horse, and speed of treadmill, DDSP-induced increase in intrathoracic pressure was associated with a significant increase in minimum (36 mm Hg), mean (82 mm Hg), and maximum (141 mm Hg) pulmonary artery pressure, compared with values for control horses (30, 75, and 132 mm Hg, respectively). Increases in pulmonary artery pressure did not induce concomitant increases in TPAP. Tracheostomy led to a significant reduction of minimum (53 mm Hg), and mean (79 mm Hg) TPAP pressure, compared with values for control horses (56 and 83 mm Hg, respectively). When adjusted for horse, speed of treadmill, and type of obstruction, all aspects of the pulmonary artery and TPAP curves were significantly decreased after administration of furosemide, compared with those for horses given saline (0.9% NaCl) solution. CONCLUSIONS: DDSP was associated with increases in pulmonary artery pressure but not with increases in TPAP. CLINICAL RELEVANCE: Expiratory obstructions such as DDSP are likely to result in pulmonary hypertension during strenuous exercise, but may not have a role in the pathogenesis of exercise-induced pulmonary hemorrhage.     

Infection of alfalfa pollen bySclerotinia sclerotiorum

Blossom blight, caused bySclerotinia sclerotiorum, has become an important disease of alfalfa (Medicago sativa L.) in seed production areas of western Canada. Studies using light microscopy and scanning and transmission electron microscopy revealed that pollen grains of alfalfa are susceptible to infection byS. sclerotiorum. Ascospores ofS. sclerotiorum germinated readily in water with or without pollen grains. Examinations of ascospore—pollen mixtures incubated at room temperature (20–22°C) for 5 days revealed that numerous pollen grains were infected byS. sclerotiorum by direct hyphal penetration through the equatorial germinative pores or through the exine and intine layers of the pollen wall without the formation of infection cushions or appressoria. After penetration, hyphae ramified within the pollen grains, causing plasmolysis of the cytoplasmic membrane and eventual disintegration of the pollen cytoplasm. The study suggests that alfalfa pollen may play a role in the epidemiology of blossom blight in alfalfa.     

Effects of calcium magnesium carbonate and roughage level on feedlot performance, ruminal metabolism, and site and extent of digestion in steers fed high-grain diets

A feedlot growth performance experiment and 2 metabolism experiments were conducted to evaluate dietary roughage concentration and calcium magnesium carbonate in steers fed a high-grain diet. In Exp. 1, one hundred ninety-two crossbred yearling steers (320 +/- 10 kg of initial BW) were fed diets based on steam-flaked corn with 0, 0.75, or 1.5% CaMg(CO(3))(2). There were no effects (P > or = 0.13) on ADG, DMI, G:F, or total water intake due to CaMg(CO(3))(2). In Exp. 2, five ruminally and duodenally fistulated steers (263 +/- 9 kg of initial BW) were used in a 5 x 5 Latin square design, with 5 dietary treatments arranged in a 2 x 2 + 1 factorial: 1) 3.8% dietary roughage and no CaMg(CO(3))(2); 2) 7.6% dietary roughage and no CaMg(CO(3))(2); 3) 11.4% dietary roughage and no CaMg(CO(3))(2); 4) 3.8% dietary roughage and 1.5% CaMg(CO(3))(2); and 5) 7.6% dietary roughage and 1.5% CaMg(CO(3))(2). Water consumption was less (quadratic, P = 0.003) when 7.6% dietary roughage was fed compared with 3.8 or 11.4% dietary roughage. Intake of DM was not affected (P > or = 0.16) by dietary roughage or by CaMg(CO(3))(2). Poststomach and total tract starch digestion decreased (linear, P < 0.01) as dietary roughage increased. Ruminal pH tended (P = 0.08) to increase as dietary roughage increased but was not affected (P = 0.60) by CaMg(CO(3))(2). In Exp. 3, DMI and ruminal pH were continuously monitored in a 6 x 6 Latin square design using 6 ruminally and duodenally fistulated Holstein steers (229 +/- 10 kg of initial BW). A 3 x 2 factorial treatment structure was utilized, with factors consisting of dietary roughage concentration (4.5, 9.0, or 13.5%) and CaMg(CO(3))(2) inclusion (0 or 1.0%) to replace MgO and partially replace lime-stone. A dietary roughage x CaMg(CO(3))(2) interaction (P = 0.01) occurred as steers consuming 13.5% roughage, 1.0% CaMg(CO(3))(2) had greater DMI per meal than those consuming 4.5% dietary roughage, no CaMg(CO(3))(2) and 9.0% dietary roughage, 1.0% CaMg(CO(3))(2). Steers consuming 13.5% dietary roughage, 1.0% CaMg(CO(3))(2) and 9.0% dietary roughage, no CaMg(CO(3))(2) had greater meal length (min/meal; P = 0.01) than steers consuming 4.5% dietary roughage, no CaMg(CO(3))(2). Total tract OM digestibility decreased linearly (P = 0.01), and ruminal pH increased linearly (P = 0.01) with increasing dietary roughage concentration. Inclusion of CaMg(CO(3))(2) can replace limestone and MgO but did not produce ruminal pH responses similar to those observed by increasing dietary roughage in high-concentrate diets.     

Chemical and sensory properties of beef of known source and finished on wet distillers grains diets containing varying types and levels of roughage

Beef knuckles (n = 160) were obtained from source-verified cattle finished on 30% wet distillers grains plus solubles enriched with varying levels of alfalfa hay (4 or 8%), corn silage (6 or 12%), or corn stalks (3 or 6%) based on NDF. Proximate analysis, pH, oxidation-reduction potential, fatty acid composition, and sensory analysis were conducted on the rectus femoris muscle to determine if roughage inclusion, in conjunction with wet distillers grains plus solubles and cattle source, affects beef flavor with particular interest in liver-like off-flavor. Proximate analysis, fat content, and oxidation-reduction potential were unaffected (P ge;0.129) by diet or source. For s.c. adipose tissue, cattle from Nebraska (NE) had greater amounts of MUFA (P = 0.048) and unsaturated fatty acids (P = 0.068) but less SFA (P = 0.065) when compared with cattle from South Dakota. Diet affected s.c. adipose tissue levels of 15:0, 17:0, and n-3 fatty acids in which cattle from NE finished on the low corn stalk diet had (P < or =0.050) lower levels. Cattle from NE had (P < or = 0.049) greater i.m. adipose proportions of 13:0 and CLA. Dietary effects (P < or = 0.050) were observed for i.m. adipose tissue proportions of 16:0, 18:1(n-9), 18:2(n-6), 20:4(n-6), 22:5(n-3), MUFA, PUFA, and n-6 fatty acids. Sensory analysis revealed that cattle from NE were (P < or = 0.023) less juicy and had less bloody notes when compared with cattle from South Dakota. Cattle finished on the low alfalfa diet were (P < or = 0.014) more tender and juicy but had more bloody notes. No (P ge; 0.670) dietary or source effects were noted for liver-like off-flavor. Subcutaneous amounts of 18:2(n-6 trans) (r = -0.17) were inversely related to the incidence of liver-like off-flavor, whereas 20:1(n-9) (r = 0.21), CLA cis-9, trans-11 (r = 0.16) were directly related. Data from this study indicate that type and level of roughage inclusion and cattle source have minimal effects on fatty acid profiles and sensory properties of the musculus rectus femoris. However, individual fatty acids of s.c. and i.m. adipose tissue were significantly correlated with liver-like off-flavor.     

Vagococcus salmoninarum I—A chronic coldwater streptococcosis in broodstock brook trout (Salvelinus fontinalis) in Wisconsin,USA

In 2018, Vagococcus salmoninarum was isolated from two lots of broodstock “coaster” brook trout (Salvelinus fontinalis) containing ~1,500 fish at the Iron River National Fish Hatchery, at which time it was identified as the causative agent of a chronic coldwater streptococcosis epizootic. Clinical signs included exophthalmia, lethargy, erratic swimming and loss of equilibrium. Female fish experienced disproportionately higher morbidity and mortality than male co-inhabitants, and routinely retained eggs following spawning. The most consistent gross clinical sign was heart pallor and turbid pericardial effusion. An attempted treatment using florfenicol was ineffective at halting the epizootic, which spanned more than a year and resulted in >50% mortality before remaining fish were culled. As there is no previous documentation of V. salmoninarum at this hatchery or in this species, it is still unclear what circumstances led to this epizootic. The inability to treat this chronic disease led to the loss of valuable broodstock, hampering ongoing fishery conservation efforts in the Great Lakes Basin.     

Vagococcus salmoninarum II—qPCR,tropism and egg-associated transmission

Vagococcus salmoninarum was identified as the causative agent of a chronic epizootic in broodstock “coaster” brook trout (Salvelinus fontinalis) at the Iron River National Fish Hatchery. The epizootic spanned more than a year, was unresponsive to multiple florfenicol treatments, and resulted in >50% mortality of the affected fish. The decision was made to cull the remaining fish during spawning, which presented an opportunity to more thoroughly examine V. salmoninarum sampling methods, organ tropism and vertical transmission. A newly developed qPCR targeting the pheS gene was used in concert with bacterial culture to show that V. salmoninarum indeed disproportionately affects females and has a tropism for female reproductive tissues. The study demonstrates that some female reproductive tissues (e.g. ovarian fluid, unfertilized eggs) are also an effective option for non-lethal detection. Despite the widespread presence of V. salmoninarum in ovarian fluid and on egg surfaces, we found no evidence of intra-ova transmission.     

芽孢杆菌HSY-8-1对植物病原真菌的抑制及其抑菌产物特性

为挖掘用于生物防治的微生物资源,自海南蚕豆枯萎病区土壤分离1株芽孢杆菌HSY-8-1,经抗菌试验分析表明,其代谢产生的拮抗物质对引发植物立枯病和根腐病的立枯丝核菌(Rhizoctonia solani)和镰刀菌(Fusariumspp.)抑菌作用较强,具有使病菌菌丝扭曲、缢缩等致畸效应,并抑制立枯丝核菌的菌核形成。研究表明,在NB液体培养基中发酵时,进入稳定生长期后开始产生抑菌物质,72 h时累积达到最大值。这种抑菌物质的特性为外泌型、水溶性,可透过0.22μm的微孔滤膜,对热、酸、碱、蛋白酶水解、紫外线照射等影响有较强的稳定性。     

Use of sclerotia of<Emphasis Type="Italic">Sclerotinia sclerotiorum</Emphasis> for efficient production of conidia of<Emphasis Type="Italic">Coniothyrium minitans</Emphasis> in liquid culture

A study was conducted to determine the feasibility of using sclerotia ofSclerotinia sclerotiorum for producing conidia ofConiothyrium minitans in liquid culture. The medium (SST) was made of water containing 2.0, 1.5, 1.0 or 0.5% (w/v) ground sclerotia ofS. sclerotiorum and 100 μgl ⁻¹ thiamine hydrochloride (HCl). One ml of conidial suspension (2 × 10⁷ conidia ml⁻¹) ofC. minitans LRC 2534 was inoculated into 100 ml of SST medium or control (thiamine HCl in water) and incubated at 20 ± 2°C on a shaker at 200 rpm. Subsamples were removed periodically and examined under a compound microscope. Conidia in the SST media germinated within 24 h, developed into branched hyphae within 48 h, produced pycnidia after 3–4 days, and the pycnidia released mature conidia after 7 days. Production of conidia varied with the concentration of sclerotia in the SST medium. It was lower (3.6 × 10⁶ conidia ml⁻¹) at 0.5% but higher (1.2 × 10⁸ conidia ml⁻¹) at 2%. The new conidia were viable and the colonies developing from them showed the original morphological characteristics. It was concluded that using SST liquid medium as a substrate for mass production of conidia ofC. minitans has potential for use in commercial development of this mycoparasite as a biocontrol product. http:www.phytoparasitica.org posting Jan. 23, 2007.     

<Emphasis Type="Italic">Ulocladium atrum</Emphasis> as a biological control agent for white mold of bean caused by<Emphasis Type="Italic">Sclerotinia sclerotiorum</Emphasis>

Field studies were conducted near Lethbridge, Alberta, Canada, in 2001, 2004 and 2005 to determine the efficacy of the antagonistic fungusUlocladium atrum for control of white mold of bean caused bySclerotinia sclerotiorum. Results of the 3 years of field trials showed that, compared with the untreated control, foliar application of a spore suspension ofU. atrum (300 ml m⁻² of 10⁶ spores ml⁻¹ suspension) significantly reduced incidence and severity of white mold, increased seed yield and reduced contamination of bean seed by sclerotia ofS. sclerotiorum. The level of control of white mold observed in the treatment ofU. atrum was similar to that of the mycoparasitic fungusConiothyrium minitans, but lower than the fungicide treatments of Ronilan (vinclozolin) at the rate of 1200 g ha⁻¹ per application in 2001, or Lance (boscalid) at the rate of 750 g ha⁻¹ per application in 2004 and 2005. The potential for use ofU. atrum as a biological control agent for sclerotinia diseases is discussed. http://www.phytoparasitica.org posting Nov. 12, 2006.