Hemagglutinins HA) of H1N1 swine influenza viruses isolated in the United States have remained antigenically and genetically conserved for many years. In contrast to such conservation, the RA of A/Swine/Nebraska/1/92 (Sw/Neb) could readily be distinguished from those of contemporary porcine viruses. Twenty-eight amino acid mutations differentiated the HA of Sw/Neb and A/Swine/Indiana/1726/88, the most recent H1N1 swine influenza virus for which HA sequence data were available. Among these differences were mutations at potential asparagine-linked glycosylation sites and charge changes at many residues. The Sw/Neb virus also could be differentiated from other swine influenza viruses in hemagglutination-inhibition assays with monoclonal antibodies to recent H1 swine HA. Nonetheless, overall sequence analysis of the HA and the nucleoprotein genes of Sw/Neb indicated that this virus was more closely related genetically to classic H1N1 swine influenza viruses than to H1N1 avian or human viruses. Infection of swine with Sw/Neb under experimental conditions induced clinical signs and lesions typical of swine influenza. However, affected swine in the field had high, persistent fevers, but relatively mild signs of respiratory tract disease. This study indicated that an antigenically and genetically novel variant of swine influenza virus was detected in the United States.

We purified porcine whey lactoferrin by affinity chromatography on a heparin-sepharose column, followed by high-performance liquid chromatography. Molecular mass of purified lactoferrin (PLF) is 78,000 daltons. The iron-binding activity of PLF had a UV/ visible-light absorption spectrum indistinguishable from that of human and bovine lactoferrins (absorbance ratio [465 nm/280 nm] approx 0.046). The growth ratio of WIL-2 cells in PLF-supplemented medium is 70% of that in serum-containing medium. The aforementioned characteristics are similar to those of human and bovine lactoferrins. Immunoblot analysis, using polyclonal antibody raised in rabbits against porcine whey lactoferrin, revealed high specificity for PLF, and low cross-reactivity with commercial human and bovine lactoferrins.

The influence of the QT, TQ, and ST intervals, and heart score on both cardiac cycle duration (RR) and diastole/systole (D/S) quotient were analyzed during the neonatal (1 day and 5 days) pigs belonging to 2 crossbreeds of different rusticity, Landrace X Belgian White (LBW) and Landrace X Duroc Jersey (LDJ). Our findings indicate that the shortening of the RR interval in 5-day-old pigs of both crossbreeds was determined by different variables in each breed. In LDJ pigs, this shortening was only associated with a shortening of ventricular activation, and in each age group, the systole and the diastole contributed equally to the RR value. The D/S quotient did not differ significantly in 1-day-old vs 5-day-old pigs, and at both ages, the quotient was only determined by the TQ value. In LBW pigs, the RR, QT, TQ, and ST were shortened, but only the shortening of QT was significant as a result of an acceleration of the ventricular recuperation process. Moreover, differences were found between 1-day-old vs 5-day-old pigs with regard to the contribution of the different intervals to the RR duration. In 1-day-old pigs, the RR depended closely on the TQ, whereas in 5-day-old pigs, all intervals contributed significantly to its duration. The D/S quotient was not significantly different in 1-day-old vs 5-day-old pigs, but a different contribution of the variables studied was observed at the 2 ages selected. In 1-day-old pigs, D/S quotient depended on the diastole duration, whereas in 5-day-old pigs, the diastole and systole contributed to its variation.

We evaluated the biochemical and hemodynamic response to hypertonic saline solution plus dextran in isoflurane-anesthetized pigs infused IV with Escherichia coli endotoxin (5 micrograms/kg of body weight for 0 to 1 hour + 2 micrograms/kg for 1 to 4 hours). After 120 minutes of endotoxemia, pigs were treated with a bolus (4 ml/kg over 3 minutes) of either normal saline solution (NSS; 0.9% NaCl), or hypertonic saline solution plus dextran (HSSD; 7.5% NaCl + 6% dextran-70). Administration of HSSD significantly (P < 0.05) increased serum osmolality and concentrations of sodium and chloride for approximately 2 hours during endotoxemia. Plasma total protein concentration decreased significantly (P < 0.05) for 2 hours after treatment with HSSD, indicating hemodilution and increased plasma volume. Although HSSD transiently increased cardiac index (CI) for approximately 15 minutes, this effect was not sustained; however, the endotoxin-induced decrease in CI was ameliorated from 120 to 180 minutes. In pigs of the endotoxin + NSS group from 180 to 240 minutes, CI decreased significantly (P < 0.05), compared with baseline and control values. The endotoxin-induced increases in mean pulmonary arterial pressure and pulmonary vascular resistance were not attenuated by HSSD. At 135 minutes, total peripheral vascular resistance was transiently lower (for approx 15 minutes) in pigs treated with HSSD, compared with control pigs. The endotoxin-induced increase in plasma lactate concentration was not attenuated by HSSD, indicating continued peripheral O2 debt. We conclude that, despite sustained increases in serum osmolality and concentrations of sodium and chloride, HSSD has only transiently beneficial cardiopulmonary effects during endotoxemia in pigs.

Virulence of three Canadian poultry strains of Salmonella enteritidis, namely phagetypes (PT) 4, 8 and 13, and one Salmonella heidelberg strain was assessed in orally and intraperitoneally inoculated one-day old chickens and compared to the virulence of a human S. enteritidis PT 4 strain from the United Kingdom (UK). The two PT 4 strains were also compared in orally inoculated adult laying hens. In addition, orally inoculated Balb/c mice were used to evaluate virulence of the above strains and two strains of Salmonella typhimurium containing different plasmids. In orally inoculated one-day old chickens, the UK S. enteritidis PT 4 strain was more virulent than the Canadian PT 4 strain. The UK PT 4 strain was also more virulent and invasive in adult laying hens than the Canadian PT 4 strain. The S. enteritidis PT 8 strain and one S. typhimurium strain isolated from a chicken hatchery were the most virulent for orally inoculated Balb/c mice. This strain of S. typhimurium contained the 60 megadalton plasmid associated with virulence for Balb/c mice which was not present in the S. typhimurium strain isolated from a pig with septicemic disease.

Embryonating eggs were inoculated with filtered porcine ileal mucosa containing intracellular curved rods (ICR) and incubated for 4 to 6 days. Three of 12 pigs given the eggs per os developed microscopic lesions of proliferative enteritis (PE). Nonchallenge-exposed control pigs did not develop lesions of PE. Four of six positive control pigs given ileal mucosa from pigs with PE also developed microscopic lesions of PE. All of the PE lesions were found in pigs necropsied 10 to 29 days after challenge exposure. None of the swine in the study had clinical signs or gross lesions of PE. Campylobacter spp were isolated from pigs with and without exposure to the ileal mucosa from pigs with PE. There was no relationship between Campylobacter spp isolation and development of lesions. Deoxyribonucleic acids extracted from embryonating chicken eggs injected with the equivalent of 0.5 mg of mucosal lesions and incubated for 4 days hybridized to a DNA probe specific for the ICR whereas DNA extracted from 1.5 mg of mucosal homogenates of the same proliferative tissue did not hybridize with the same probe. Results of these experiments indicated that ICR injected into eggs remained infective for pigs and suggest replication of ICR in the first-passage eggs.

The ability of viral glycoproteins (VP) VP4/VP7 reassortant swine rotaviruses (RV) to induce cross-neutralizing antibody against parental serotypes was investigated in guinea pigs. Using selective culture conditions, we produced 10 reassortant viruses that contained gene segment 4 of the OSU RV strain and gene segment 9 of the Gottfried RV strain. These reassortant RV grew to high titer in cell culture and were neutralized by monospecific antisera against both parental RV strains. The reassortant RV were chemically inactivated with binary ethylenimine, adjuvanted with aluminum hydroxide, and used to produce antisera in guinea pigs. The hyperimmune antisera had high neutralization titer against both parent RV strains. These results indicate that several of the reassortant RV may be capable of inducing neutralizing antibodies to VP4 and VP7 and may have future use as bivalent vaccine strains.

From 2 to 4.5 months of age, 80 crossbred gilts were reared in a conventional grower unit where they were naturally exposed to mycoplasmal and bacterial pathogens that cause pneumonia and atrophic rhinitis. At 4.5 months of age, gilts were moved to environmentally regulated rooms (4.9 X 7.3 m) and assigned at random to 1 of 2 treatment groups: low aerial concentration of ammonia (4 to 12 ppm; mean, 7 ppm) or moderate aerial concentration of ammonia (26 to 45 ppm, mean, 35 ppm). Low concentration of ammonia was obtained by flushing of manure pits weekly, whereas moderate concentration of ammonia was maintained by adding anhydrous ammonia to manure pits that were not flushed. Gilts were weighed biweekly. Mean daily gain (MDG) was less (P < 0.01) for gilts exposed to moderate concentration of ammonia than for gilts exposed to low concentration of ammonia after 2 weeks in their respective environments. By 4 and 6 weeks, however, MDG was similar between the 2 treatment groups. After 6 weeks in these environments, 20 gilts from each treatment group were slaughtered, and prevalence and severity of lung lesions and snout grades were determined. At slaughter, body weight was greater (P < 0.01) in gilts exposed to low, rather than moderate, ammonia concentration (94.5 vs 86.8 kg; SEM, 3.3 kg). Percentage of lung tissue containing lesions (18 vs 12) and snout grade (2.8 vs 3.1) were similar between gilts exposed to low or moderate concentration of ammonia. The remaining 20 gilts in each treatment group were maintained in their respective environments, exposed daily to mature boars and bred at first estrus. Age at puberty was similar between gilts exposed to low or moderate concentration of ammonia (208 vs 205 days; SEM, 1.3 days), even though weight at puberty was less (P < 0.03) for gilts exposed to low concentration of ammonia than for gilts exposed to moderate concentration of ammonia (109.7 vs 118.2 kg; SEM, 4.5 kg). At day 30 of gestation, number of live fetuses (10.6 vs 11.7), fetal length (2.53 vs 2.57 cm), and fetus-to-corpus luteum ratio (0.85 vs 0.78) were similar between gilts at low and moderate ammonia environments. These data indicate that exposure of gilts to mean aerial ammonia concentration of 35 ppm in environmentally regulated rooms depressed MDG for 2 weeks, but failed to alter onset of puberty or litter size at day 30 of gestation.

Ultrastructures of knobbed spermatozoa in a boar were observed. The knobs, found at the apex of the spermatozoa, were spherical swellings of the acrosome; vacuoles were found in the swellings. According to the contents, 2 types of the vacuoles were recognized: a vacuole containing cell debris that was surrounded by 2 or 3 layers of membranes, and a vacuole containing an amorphous material that was surrounded by a single membrane. Several vacuoles might be observed in a knob. Observations of both testes indicated that the cell debris in the vacuole of the knob was derived from the cytoplasm of the Sertoli cell, which evaginated into the spermatid. Origin of the amorphous material in the other type of knob is not known.

In an abattoir-based case-control study, histologic, and macroscopic examination of porcine intestines at slaughter and 2 molecular assays were compared for use as diagnostic tests of proliferative enteritis (PE). Fecal samples and intestinal specimens were collected from pigs with grossly thick ileum and from clinically normal pigs at slaughter. Tissue specimens were fixed in neutral buffered 10% formalin, and sectioned. Sections stained with H&E were examined for proliferative lesions by a pathologist unaware of the group to which the pig had been assigned on the basis of results of gross examination. Adjacent tissue sections, stained with Warthin-Starry (silver) stain, were examined for presence of the intracellular bacterium of PE, ileal symbiont (IS)-intracellularis, in the enterocytes of the intestinal crypts by the senior author, who was unaware either of the group to which the pig had been assigned or diagnosis by the pathologist. Bacterial DNA was extracted from the fecal samples and assayed by dot-blot hybridization and polymerase chain reaction (PCR) for presence of IS-intracellularis DNA, without knowledge of results of the other examinations. The PCR assay for IS-intracellularis was a specific and sensitive diagnostic test for PE, and dot-blot hybridization was sensitive, but was less specific. Macroscopic examination of intestines at slaughter was a sensitive, but not specific, test. Association between IS-intracellularis and proliferative lesions was statistically examined in the same study. There was a highly significant (P = 0.0078) association between presence of naturally acquired proliferative lesions and intracellular infection induced by IS-intracellularis. The odds ratio of greater than or equal to 14 and estimated attributable fraction of greater than or equal to 92% indicate that IS-intracellularis may be a necessary cause of PE.