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.     

Primary cardiac granular cell tumor in a dog

The histological, histochemical, and ultrastructural features of a granular cell tumor in the wall of the right atrium of the heart in a nine-year-old dog are described. The histologic appearance of the mass varied from areas of spindle-shaped cells to sheets of globoid cells with foamy granular cytoplasm. The globoid neoplastic cells contained numerous cytoplasmic granules which were variably positive to periodic acid-Schiff staining, with and without disastase digestion. Ultrastructurally, the globoid cells had numerous various-sized, heterogeneous lysosomes with pleomorphic content. A granular cell tumor originating in the heart has not been reported previously in animals. The support for a neural origin of these tumors by the recent identification of several nervous tissue specific proteins in their granular cells is discussed.     

Experimental and naturally occurring transplacental transmission of canine distemper virus

In the present study, 2 different effects of experimentally induced infection with virulent canine distemper virus (CDV) on pregnant CDV-susceptible dogs were studied. In 1 bitch, abortion occurred 7 days after viral inoculation and there was no evidence of fetal infection. Another bitch had subclinical infection and delivered 3 CDV-infected pups. Sequential clinical, immunologic, and virologic studies of a litter of gnotobiotic pups (3rd bitch) that were congenitally infected with CDV demonstrated the heightened susceptibility to CDV in the neonatal period. The data presented add canine distemper to the list of transplacental infectious diseases in the canine species.     

Ejaculation does not contribute to the stress response to electroejaculation in sheep

Electroejaculation procedures (EEPs) provoke stress; nevertheless, ejaculation produces physiological changes similar as those usually used to measure stress responses. The application of EEP to animals that cannot ejaculate—as ewes—may be useful to discriminate the responses induced by ejaculation from those provoked by EEP. The aim was to determine the stress response to EEP in rams and ewes. The EEPs were applied to 10 rams and 10 ewes during the non‐breeding season, and the number of vocalizations, the heart rate, rectal temperature, serum cortisol concentration, biochemical and haematological parameters were measured. Overall, EEP provoked increases in cortisol concentration, glycaemia, rectal temperature and concentration of creatine kinase (all them: p < .0001) as well as relative concentration of granulocytes (p = .003) and absolute granulocyte concentration (p = .0002) in both, rams and ewes. Heart rate, relative concentration of lymphocytes (p = .001), haematocrit (p = .02) and haemoglobin (p = .045) decreased in animals from both genders after EEP. Besides, cortisol (p < .0001), rectal temperature (p = .002) and glycaemia (p = .001) were greater in ewes than rams, and creatine kinase also tended to be greater in ewes than rams (p = .054). On the other hand, the number of animals that vocalized (p = .006), white blood cells (p = .02) and absolute lymphocytes (p = .02) were greater in rams than ewes. The general trends show a similar pattern of stress responses in animals from both genders. Therefore, we concluded that ejaculation does not contribute to the stress response provoked by the EEP. This procedure also provokes muscular damage and probably pain.     

In vivo CXCR4 expression, lymphoid cell phenotype, and feline immunodeficiency virus infection

Primary isolates of feline immunodeficiency virus (FIV) appear to require binding to CD134 in conjunction with CXCR4(X4) to infect IL-2-dependent T-cell-derived cells in culture. However, much less is known about the role of X4 for the infection of cells in vivo. To investigate the correlation between X4 expression and FIV infection in cats acutely infected with FIV-C-Pgmr we used high-speed fluorescence-activated cell sorting and realtime PCR to co-analyze cell phenotypes from lymph node, thymus, bone marrow and blood for FIV infection and X4 expression. X4 expression was greatest in lymph node, both in frequency and in mean fluorescence intensity. The thymus demonstrated a higher proviral burden in X4+ thymic T cells (14% in X4+ thymic T cells and 7% in X4− cells) whereas, proviral loads were similar between X4+ and X4− cell populations in all other tissues examined. Assuming a minimum of one proviral copy per cell, a maximum of 50% of FIV-positive cells were X4+. The highest fraction of FIV-infected X4− cells was present in bone marrow. Regardless of X4 status, proviral loads were higher in lymph node and blood T cells than in B cells. These studies provide both a positive association between X4 expression and FIV infection and introduce the probability that X4-independent infection occurs in other target cells in vivo.     

Production of enterotoxin(s) by Staphylococcus hyicus

Five strains of Staphylococcus hyicus (3 of subspecies hyicus and 2 of chromogenes) were tested serologically for their ability to produce known and unknown enterotoxin(s) and were also examined using monkey bioassays. None of the 5 strains produced any detectable level of the known enterotoxins A—E. However, all of them produced emetic responses in 2 or more of 6 cynomologus monkeys when culture growth was fed intragastrically. One of the 5 strains (S. hyicus subspecies hyicus, VII 76) produced emetic responses in 3 of 6 monkeys with 50 ml of culture growth. The other 4 strains required 1 l of culture broth (concentrated 20-fold) to produce an emetic response in at least 2 of 6 monkeys. Enterotoxin production is, therefore, not unique to S. aureus species. Since some of these organisms do not produce coagulase and thermonuclease, they would be ignored in food hazard evaluation.     

Circulating Metabolic Hormones During the Peripubertal Period and Their Association with Testicular Development in Bulls

The objective of the present study was to characterize changes in serum metabolic hormones concentrations from 20 weeks before to 20 weeks post-puberty in bulls and to investigate the associations of metabolic hormones concentrations with testicular development. Leptin concentrations increased from 16 weeks before puberty to 8 weeks post-puberty and insulin concentrations increased from puberty to 8 weeks post-puberty. Growth hormone concentrations decreased after 4 weeks post-puberty, whereas IGF-I concentrations increased from 8 weeks before puberty to 8 weeks post-puberty. During this period, testicular growth was accelerated and testosterone secretion increased substantially, without any significant changes in gonadotropin secretion. Monthly circulating concentrations of leptin, IGF-I and insulin accounted for 63% of the variation in scrotal circumference and 59% of the variation in paired testes volume. In conclusion, the secretion of metabolic hormones was not associated with changes in gonadotropins concentrations. Furthermore, the associations of leptin, IGF-I and insulin concentrations with testes size indicated that these hormones might be involved in a gonadotropin-independent mechanism regulating the testicular development in peripubertal bulls.     

Elaboration of chemotactic substances by alveolar cells: possible mechanisms for the initial neutrophilic response in feline caliciviral pneumonia.

In vitro experiments established that the interaction of feline calicivirus (FCV) with alveolar macrophages and pneumocytes results in the generation of chemotactic factors that produce directed migration of neutrophils in Boyden chambers. Factors were produced independent of immune mechanisms and of discernible serum factors. Lysates of noninfected alveolar macrophages and pneumocytes did not possess chemotactic activity, indicating that chemotactic factors were not preformed in these cells. Noninfected alveolar macrophages also elaborated neutrophil chemotactic factors in culture; however, activity was greater when macrophages were infected with FCV. The results of this study suggested that the neutrophilic response in the peripheral portion of the lung of cats exposed to aerosols of FCV was the result of the elaboration of complete chemotactic factors from FCV-infected alveolar cells.     

Pathogenesis of acute toxoplasmosis in specific-pathogen-free cats

Systemic toxoplasmosis was produced in specific-pathogen-free cats by intravenous inoculation with Toxoplasma gondii tachyzoites. Infectious organisms were recovered from all tissues studied, but the number of organisms recovered from liver, lungs and spleen was 10-fold to 10,000-fold higher than from heart and brain. The occurrence and severity of Toxoplasma-induced lesions correlated with the number of infectious organisms recovered from the various tissues. In nonlymphoid tissues, the Toxoplasma-associated lesions consisted of multifocal necrosis, usually with demonstrable organisms. Lesions in the spleen and mesenteric lymph nodes consisted of reticuloendothelial and lymphoid hyperplasia, with few demonstrable organisms. Pneumonitis was severe and sometimes fatal in the early stages of systemic toxoplasmosis. Light- and electron-microscopic studies showed that the earliest lung lesions were randomly distributed infiltrates of neutrophils, eosinophils, and mononuclear cells into alveolar walls. Later lesions were diffuse alveolar necrosis, pneumocytic hyperplasia, and extensive fibrinocellular exudates in alveoli. Tachyzoites were present in cytoplasmic vacuoles of fibroblasts, macrophages, type I and II pneumocytes, bronchiolar epithelial cells, bronchiolar smooth muscle cells, endothelial cells, neutrophils, and eosinophils, and circulating monocytes. Replication of organisms was found in all parasitized cell types except neutrophils and eosinophils.