Experimental infection of pigs and ferrets with "pre-pandemic," human-adapted, and swine-adapted variants of the H1N1pdm09 influenza A virus reveals significant differences in viral dynamics and pathological manifestations.

Influenza A viruses are RNA viruses that cause epidemics in humans and are enzootic in the pig population globally. In 2009, pig-to-human transmission of a reassortant H1N1 virus (H1N1pdm09) caused the first influenza pandemic of the 21st century. This study investigated the infection dynamics, pathogenesis, and lesions in pigs and ferrets inoculated with natural isolates of swine-adapted, human-adapted, and "pre-pandemic" H1N1pdm09 viruses. Additionally, the direct-contact and aerosol transmission properties of the three H1N1pdm09 isolates were assessed in ferrets. In pigs, inoculated ferrets, and ferrets infected by direct contact with inoculated ferrets, the pre-pandemic H1N1pdm09 virus induced an intermediary viral load, caused the most severe lesions, and had the highest clinical impact. The swine-adapted H1N1pdm09 virus induced the highest viral load, caused intermediary lesions, and had the least clinical impact in pigs. The human-adapted H1N1pdm09 virus induced the highest viral load, caused the mildest lesions, and had the least clinical impact in ferrets infected by direct contact. The discrepancy between viral load and clinical impact presumably reflects the importance of viral host adaptation. Interestingly, the swine-adapted H1N1pdm09 virus was transmitted by aerosols to two-thirds of the ferrets. Further work is needed to assess the risk of human-to-human aerosol transmission of swine-adapted H1N1pdm09 viruses.

Avian and Human Influenza A Virus Receptors in Bovine Mammary Gland.

An outbreak of influenza A (H5N1) virus was detected in dairy cows in the United States. We detected influenza A virus sialic acid -α2,3/α2,6-galactose host receptors in bovine mammary glands by lectin histochemistry. Our results provide a rationale for the high levels of H5N1 virus in milk from infected cows.

Increased preload and echocardiographic assessment of diastolic function.

AIMS: Echocardiographic diastolic parameters are used to diagnose and monitor increased left ventricular filling pressure (LVFP) and we hypothesized that increased loading conditions cause increased E/e'. Our aim was to assess the effect of preload augmentation on diastolic parameters among both healthy subjects and subjects with known cardiac disease. METHODS AND RESULTS: We included 129 subjects merged from two cohorts; one dialysis cohort (n = 47) and one infusion cohort (n = 82). Echocardiography was performed immediately before and after hemodialysis (HD) or saline infusion, under low and high loading conditions. Elevated LVFP was defined as septal E/e' ≥ 15 and/or lateral E/e' ≥ 13 at high-loading conditions. The population was divided according to elevated LVFP (n = 31) and normal LVFP (n = 98). The load difference for the population was 972 ± 460 mL, with no differences in load difference between elevated and normal LVFP (p NS). The subjects with elevated LVFP were older (63 ± 11 vs. 46 ± 16 years, p < .001), and had lower LV ejection fraction (50 ± 14 vs. 59 ± 8.1%, p < .01). After augmented preload, EDV increased in the normal LVFP group (p < .01) but remained unchanged in the elevated LVFP group (p NS). Both E and e' increased among the subjects with normal LVFP, whereas E/e' remained unchanged (∆E/e' +.1 [-.5-1.2]), p NS). Among the subjects with elevated, LVFP we observed increased E but not e', resulting in significantly increased E/e' (∆ average E/e' +2.4 [0-4.0], p < .01). CONCLUSION: Augmented preload does not seem to affect E/e' among subjects with normal LVFP, whereas E/e' seems to increase significantly among subjects with elevated LVFP.

Right Ventricular and Pulmonary Vascular Function are Influenced by Age and Volume Expansion in Healthy Humans.

BACKGROUND: Patients with heart failure (HF) often show signs of right ventricular (RV) dysfunction. The RV function of coupled with the pulmonary circulation (tricuspid annular plane systolic excursion [TAPSE]/pulmonary arterial systolic pressure [PASP]) has been shown to divide HF patients into distinct prognostic strata, but less is known about which factors influence this prognostic marker, and whether those factors can be modified. We sought to obtain normative values and discern the individual effects of age, sex, and fluid overload on RV function. METHODS AND RESULTS: Sixty healthy subjects aged 20-80 years were enrolled in this prospective study. Right heart catheterization with hemodynamic measurements were performed at rest after a rapid saline solution infusion (10 mL/kg, 150 mL/min). Linear regression and Spearman correlation models were used to estimate associations between TAPSE/PASP and relevant variables. In healthy persons of all ages, the median (5th-95th percentiles) normative TASPE-PASP ratio was 1.25 (0.81-1.78) mm/mm Hg. The correlation between progressive age and declining TAPSE/PASP was significant (r = -0.35; P = .006). Sex did not influence TAPSE/PASP (P = .30). Rapid fluid expansion increased central venous pressure from 5 ± 2 mm Hg to 11 ± 4 mm Hg after fluid infusion (P < .0001). This resulted in a 32% decrease in the TAPSE-PASP ratio after fluid infusion, compared to baseline (P < .0001). CONCLUSIONS: The TAPSE-PASP ratio was affected by age, but not sex. TAPSE/PASP is not only a reflection of intrinsic RV function and pulmonary vascular coupling, but fluid status also dynamically affects this index of RV function. Normative values with invasive measurements were obtained for future assessment of HF patients.

Longitudinal field studies reveal early infection and persistence of influenza A virus in piglets despite the presence of maternally derived antibodies.

A longitudinal study was performed in three Danish farrow to grower (30 kilos) herds over a 4-month period to investigate the dynamics and clinical impacts of influenza A virus (IAV) infections. In each herd, four batches consisting of four sows each with five ear-tagged piglets were included. Nasal swabs and/or blood were sampled from the sows and/or the piglets prior to farrowing and at weeks 1, 3, and 5 and at the end of the nursery period. Clinical examinations were performed at each sampling time. The sows and piglets were tested for IAV and IAV antibodies in nasal swabs and blood samples, respectively. The results revealed three enzootically infected herds, where the majority of the pigs were infected during the first 5 weeks after birth. Infected piglets of only 3 days of age were detected in the farrowing unit, where the sows were also shedding virus. In all herds, low to moderate numbers of infected pigs (ranging from 3.6 to 20.7%) were found to be virus positive in nasal swabs at two consecutive sampling times. Furthermore, clinical signs of respiratory disease were associated with IAV detection. The findings of this study documented that IAV can persist in herds and that piglets as young as 3 days can be infected despite the presence of maternally derived antibodies.

Antimicrobial prescription data in Danish national database validated against treatment records in organic pig farms and analysed for associations with lesions found at slaughter.

BACKGROUND: Antimicrobial use (AMU) in livestock is a debated topic, mainly due to the risk of associated development of antimicrobial resistance. There is focus on reducing AMU in the Danish pig production, which accounts for the largest proportion of AMU for animals in Denmark. Due to special restriction on AMU in organic pig production, the AMU in organic pig production is lower than in conventional pig production. There is concern that reduced AMU could jeopardize animal health and welfare, if it reflects insufficient treatment of sick animals, which might be reflected by the prevalence and types of lesions found at meat inspection. However, little is known about the associations between AMU and meat inspection findings in pigs from organic farms. Furthermore, excess amount of antimicrobial product after a treatment cannot be re-prescribed in organic pig herds. The initial prescription is recorded in the national database VetStat, but the unused amount is not deducted leading to uncertainty when reporting AMU. The objectives of this study were to 1) describe AMU patterns based on prescription data for organic pig production and compare with those of the conventional pig production for year 2016, 2) study the associations between herd-level AMU prescription data and meat inspection data for organic pig herds and 3) validate herd-level AMU prescription data in VetStat against treatment records collected on-farm in organic Danish pig herds. RESULTS AND CONCLUSIONS: Gastrointestinal indications account for the largest proportion of AMU in both organic pig herds (65 and 54% of treatment doses for weaners and finishers, respectively) and conventional pig herds (80 and 68% of doses for weaners and finishers, respectively). A larger proportion is prescribed for respiratory indications in organic than conventional weaners and arthropathic indications in finishers. No associations between AMU and meat inspection data were found. This needs further investigation as the prevalence of lesions at slaughter was slightly (non-significantly) higher in herds with no registered AMU than with AMU prescriptions. Only 8 out of 31 herds had recorded their AMU sufficiently detailed to compare, and using VetStat as a proxy for AMU led to 9-88% overestimation of the actual use in 7 out of these 8 herds and 120% underestimation in one herd.

Global longitudinal strain before cardiac surgery: Improving feasibility, reproducibility, and variability.

BACKGROUND: Global longitudinal strain (GLS) is a predictor of outcome after cardiac surgery. If integrated into clinical decision-making and timing of surgery, it is important to evaluate the feasibility, reproducibility, and variation of GLS in this selection of patients, where poor image quality and nontraceable segments are frequent. METHODS AND RESULTS: Two-dimensional strain analysis was performed on 250 patients planned to undergo open-heart surgery. Intra- and inter-examiner retest variability was assessed in 50 consecutive patients. All myocardial segments were traceable in 119 patients, and GLS of those served as a reference in comparison with alternative strain models with nontraceable segments. Global longitudinal strain estimation by the recommended method of a maximum of one nontraceable segment per view was only feasible in 64% of cases (mean GLS -16%). Reproducibility was moderate (intra-observer coefficient of variation [CV] 8%; inter-observer CV 10%) and variation of GLS showed bias ± 95% limits of agreement (LOA) of 0.6 ± 1.1 (P < .05). Accepting three nontraceable segments in total increased feasibility to 77% with similar reproducibility (intra-observer CV 8%; inter-observer CV 11%) and variation (bias ± LOA: 0.6 ± 1.3, P < .05). A model with a maximum of one apical, one mid, and one basal nontraceable segment increased feasibility to 72% with similar reproducibility (intra-observer CV 8%; inter-observer CV 10%) and variation (bias ± LOA: 0.4 ± 1.2, P < .05). CONCLUSION: Global longitudinal strain estimation in patients prior to cardiac surgery is challenged by moderate feasibility, retest variation as well as variation in cases of nontraceable segments. We suggest alternative strain models with improved feasibility without compromising reproducibility and variation.

Semi-automated estimation of left ventricular ejection fraction by two-dimensional and three-dimensional echocardiography is feasible, time-efficient, and reproducible.

PURPOSE: To compare two-dimensional (2D) and three-dimensional (3D) methods to estimate left ventricular ejection fraction (LVEF) with respect to feasibility, time consumption, and retest reproducibility. METHODS: A total of 100 patients planned to undergo coronary artery bypass grafting and/or aortic valve replacement were included consecutively. 2D and 3D echocardiography was performed on all patients. Acquisition and analysis time as well as intra- and inter-examiner variability were assessed in 50 consecutive patients with 3 repeated echocardiographic examinations and analyses. LVEF was estimated by five different methods: uniplane, biplane, and single-beat triplane (SB3P), as well as semi-automated biplane (AutoEF) and 3D volumetric tracings (4D Auto LVQ). All methods were compared to Simpson's biplane method and feasibility was determined. RESULTS: Feasibility of Simpson's uniplane method, Simpson's biplane method, AutoEF, SB3P, and 4D Auto LVQ was 97%, 92%, 86%, 70%, and 89%, respectively. All methods evaluated were 18%-33% faster (P < 0.001) than Simpson's biplane method (115 seconds, standard deviation 15 seconds). Compared to Simpson's biplane method mean LVEF was slightly underestimated by 4D Auto LVQ (-2 ± 8%, P = 0.02), but not significantly different when assessed by the other methods. AutoEF and 4D Auto LVQ showed the lowest test variability (intra-examiner coefficient of variation (CV) 10%-11%; inter-examiner CV 10%-12% vs intra-examiner CV 12%-18%; inter-examiner CV 12%-20%). CONCLUSIONS: Estimation of LVEF by modern semi-automated 2D and 3D echocardiographic modalities is feasible, time-efficient, and reproducible.

Spatial analysis and temporal trends of porcine reproductive and respiratory syndrome in Denmark from 2007 to 2010 based on laboratory submission data.

BACKGROUND: Porcine reproductive and respiratory syndrome (PRRS) has been a cause for great concern to the Danish pig industry since it was first diagnosed in 1992. The causative agent of PRRS is an RNA virus which is divided into different genotypes. The clinical signs, as well as its morbidity and mortality, is highly variable between herds and regions. Two different genotypes of PRRS virus (PRRSV) are found in Denmark: type 1 and type 2. Approximately 40% of Danish swine herds are seropositive for one or both PRRSV types. The objective of this study was to describe the temporal trend and spatial distribution of PRRSV in Danish swine herds from 2007 to 2010, based on type-specific serological tests from the PRRS surveillance and control program in Denmark using the results stored in the information management system at the National Veterinary Institute, Technical University of Denmark (DTU Vet). RESULTS: The average monthly seroprevalence of PRRSV type 1 was 9% (minimum of 5%; maximum of 13%) in breeding herds, and 20% (minimum of 14%; maximum of 26%) in production herds; PRRSV type 2 had an average seroprevalence of 3% (minimum of 1%; maximum of 9%) in breeding herds and of 9% (minimum of 5%; maximum of 13%) within production herds. The seroconversion rate followed a similar and consistent pattern, being higher for type 1 than for type 2 for both PRRSV types. Regarding the spatiotemporal results, the relative risk distribution maps changed over time as a consequence of the changes in PRRSV seroprevalence, suggesting a general decline in the extent of areas with higher relative risk for both type 1 and 2. Local spatial analysis results demonstrated the existence of statistically significant clusters in areas where the relative risk was higher for both herds. CONCLUSIONS: PRRSV type 1 seroprevalence was constantly higher than for PRRSV type 2 in both herd types. Significant spatial clusters were consistently found in Denmark, suggesting that PRRSV is endemic in these areas. Furthermore, relative risk distribution maps revealed different patterns over time as a consequence of the changes in seroprevalence.

The avian influenza A virus receptor SA-α2,3-Gal is expressed in the porcine nasal mucosa sustaining the pig as a mixing vessel for new influenza viruses.

Influenza A viruses (IAVs) originate from wild birds but have on several occasions jumped host barriers and are now also circulating in humans and mammals. The IAV host receptors (glycans with galactose linked to a sialic acid (SA) in an α2,3 or α2,6 linkage) are crucial host factors restricting inter-species transmission. In general, avian-origin IAVs show a preference for SA-α2,3 (avian receptor), whereas IAVs isolated from humans and pigs prefer SA-α2,6 (human receptor). N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc) are the two major SAs. Neu5Ac is expressed in all species, whereas Neu5Gc is only expressed in a limited number of domestic species such as pigs and horses, but not in humans. Despite that previous studies have shown that the IAV host receptor distribution appears to be similar in pigs and humans, none of these studies have investigated the expression of Neu5Gc-α2,6 in situ in porcine tissues. Thus, the aim of this study was to elucidate the distribution of IAV host receptors expressed in the porcine respiratory tract and relate the expression to the viral tropism of diverse host-adapted IAVs. The IAV receptor (SA-α2,3 and SA-α2,6) distribution and the presence of specifically Neu5Gc-α2,6 in the porcine nasal, tracheal, and lung tissues was investigated by lectin histochemistry. Furthermore, IAV immunohistochemistry was performed on tissues from pigs experimentally infected with IAVs, either adapted to pigs or humans, to investigate the significance of the IAV host receptors and the tropism of the diverse host-adapted IAVs. We document for the first time the expression of the avian receptor on the surface of the porcine nasal mucosa and an equal expression of Neu5Ac-α2,6 and Neu5Gc-α2,6 on the surface of the tracheal epithelium and alveoli. In all IAV-infected pigs, we found a low amount of IAV-positive cells in the trachea despite a high expression of the human receptor. Cumulatively, these findings suggest that optimal IAV replication involves a complex interplay between the viruses and their host receptors and that there might be other less clearly defined host factors that determine the site of replication.