Molecular characterization of Haemophilus parasuis ferric hydroxamate uptake (fhu) genes and constitutive expression of the FhuA receptor

Bacteria have evolved a set of highly specialized proteins to capture iron in iron-depleted environments. The acquisition and uptake of iron present in the extracellular milieu of eukaryotic organisms is indispensable for the growth and survival of microbial pathogens in the course of infection. Haemophilus parasuis is the causative agent of Gl?sser disease, which is responsible for considerable financial losses in pig-rearing worldwide. To gain insight into the mechanisms involved in siderophore-mediated iron uptake in H. parasuis, genes in the H. parasuis ferric hydroxamate uptake (Fhu) region were amplified in the work being reported here. As has been described in A. pleuropneumoniae, an Fhu genomic region was also present in H. parasuis, being composed of four potential consecutive open reading frames (ORF) designated as fhuC, fhuD, fhuB, and fhuA, respectively. By immunoblotting, using a cross-reactive polyclonal antibody raised against Actinobacillus pleuropneumoniae FhuA protein, it was demonstrated that this protein was constitutively expressed in H. parasuis and its level of expression was not modified under conditions of restricted iron availability. This is the first report describing the presence of the fhu genes in H. parasuis. Our results indicate that FhuA protein expression is not affected under iron-restricted conditions, however, it is one of the targets of the humoral immune response.     

Influence of murine Toxocara canis infection on plasma and bronchoalveolar lavage fluid eosinophil numbers and its correlation with cytokine levels

Toxocara canis is a nematode of the Ascaridae family that normally parasites the small intestine of canid species. Humans are accidentally infected upon ingestion of embryonated eggs, and can manifest several clinical alterations such as fever, hepatomegaly, splenomegaly, respiratory symptoms, muscle pain and anorexia. In the present work, we investigated the kinetics of tissue distribution of L2 larva in lungs, liver, kidney, brain, skeletal muscle and myocardium. Also, we analyzed the blood and bronchoalveolar lavage fluid (BAL) for levels of IL-6, IFN-gamma, eotaxin and Regulated on Activation Normal T Cell Expressed and Secreted (RANTES) in experimental murine T. canis infection. We observed liver, lung and kidney lesions correlated to larva migration as early as the first day of infection. After the seventh post-infection day, larva could also be detected in brain, skeletal muscle and heart, as an indicator of biphasic migration pattern. Increased inflammatory activity was detected in BAL and plasma of infected animals, as was an intense eosinophil migration associated with an increase in the levels of all the cytokines studied. In conclusion, our results establish a tight correlation between tissue lesions caused by larva migration and increased plasma levels of pro-inflammatory and eosinophil chemotactic cytokines. Thus, murine T. canis infection may prove to be useful in understanding the role of cytokines in infection.     

Pathological and aetiological studies of multifocal interstitial nephritis in wasted pigs at slaughter

Multifocal interstitial nephritis in pigs has been associated with several infectious agents. The objective of the present study was to investigate several different potential infectious agents associated with "white-spotted" kidneys in pigs suffering from wasting at slaughter (aged 6-8 months). Twenty-nine case kidneys (with a "white-spotted" gross appearance) classified into 3 macroscopic lesional grades, and 15 control kidneys (lacking gross lesions), were obtained from a pig abattoir. Laboratory analyses to detect potential associations with the aforementioned pathological condition with Leptospira spp., porcine circovirus type 2 (PCV2), porcine parvovirus (PPV), porcine reproductive and respiratory syndrome virus (PRRSV), and bacteria, were carried out. Microscopically, interstitial nephritis with a lymphofollicular inflammatory pattern (follicular nephritis) was observed in both case and control kidneys, with a higher frequency seen in the former ones. No leptospires were identified, although antibodies to the Pomona and Bratislava serovars were detected. Some pyogenic bacteria were also isolated from both case and control kidneys. PCV2 nucleic acid was only detected in 1 case kidney. PRRSV antigen was not found in any tested sample. Some pigs were tested positive for PPV by serology. Apparently, none of the studied agents were specifically associated as being the potential cause of the renal lesions in the studied wasted pigs. The fact that these chronic lesions may have been the consequence of a previous infection with one of these studied microorganisms, or more, and eventually with other non-tested infectious agents during the growing-finishing period, cannot be ruled out.     

Piroplasma infection in dogs in northern Spain

Babesiosis is a world-wide zoonosis caused by tick-borne hematozoan parasites of the genus Babesia. Canine Babesidae have historically been classified as "large Babesia" (Babesia canis) and "small Babesia" (Babesia gibsoni) based on the size of their intraerythrocytic forms. Genetic sequencing technology using the polymerase chain reaction (PCR) has allowed further subdivision. B. gibsoni has three strains: "Asia", "California" and a recently identified small babesial-like parasite, Theileria annae. This newly recognised piroplasm appears to be hyperendemic in northwest Spain. In order to provide some insight into the situation, all the cases diagnosed in our laboratory (NW of Spain) during 2003 were evaluated. Our study (62 samples) shows the existence of a piroplasm morphologically different from B. canis and similar to B. gibsoni, which is genetically related to T. annae. Severe regenerative anemia and thrombocytopenia are almost constant characteristics of infection with T. annae in dogs. In many cases azotemia is found. Abnormally high serum concentrations of urea and creatinin, together with elevated concentrations of inorganic phosphorus, hypoalbuminemia, hypercholesterolemia, proteinuria, high protein/creatinin and presence of hyaline and granular casts in the microscopic examination of urine sediment suggest a glomerular component to the disease. We conclude that observational research and clinical trials should be conducted in order to improve our understanding of this emerging disease in order to provide some insight into the best therapeutic practices.     

山麻雀命名的考证

山麻雀是一种广布的小型鸣禽,拉丁学名通常为Passer rutilans (Temminck).经作者考证,该种名发表于1836年12月31日,但在此之前,Gould已于1836年4月8日发表了该种并命名为Passer cinnamomeus.因此,根据动物命名法中的优先原则,该种应称作Passer cinnamomeus (Gould,1836).其公认的3个亚种也应分别称作P.cinamomeus rutilans (Temminck,1836),P.cinnamomeus intensior Rothschild,1922及P.cinnamomeus cinnamomeus (Gould,1836).     

Gastrointestinal parasites presence during the peripartum decreases total milk production in grazing dairy Holstein cows

Parasitism in cattle is known to impair growth and development. Recent findings suggest that productivity of adult animals is also affected, but little is known about the physiological mechanisms involved. Furthermore, development of nematode resistance to drugs makes imperative the search of management practices that avoid whole herd treatment. We undertook an epidemiological and endocrine study in a grass based dairy farm in Argentina to study the effect of parasites on milk production and the underlying mechanisms involved, and identify individual animals that would benefit from antiparasitic treatment. All the cows in the dairy were followed monthly for egg parasite output in feces. Samples were cultured for genera determination. Milk production and reproductive results were recorded and periodical bleedings for hormone determination were performed. Nematode egg output (EPG) was maximal in late Summer and Autumn and minimal in Spring in coincidence with the Ostertagia inhibition-disinhibition cycle as this genus had the highest prevalence in all the study. The highest proportion of positive samples was found in the high producing herd and maximal counts were found in the peripartal period. Milk production did not correlate with EPG mean values but, when cows were grouped by EPG positivity around parturition, a significant difference in total milk production between EPG null and positive cows was observed. Positive cows produced 7%, 12% or 15% less milk than null EPG cows, depending on the sampling month/s chosen for classification. The highest difference was seen when both prepartum and postpartum samples were taken into account. No difference in lactation length and a marginal effect on partum to first service interval were encountered. Endocrine studies revealed a decrease in serum growth hormone (GH), type I insulin-like growth factor (IGF-I) and prolactin during lactation in cows with positive EPG in the first postpartum sample with respect to null EPG cows at that time. GH levels decreased and prolactin and IGF-I levels increased in both groups of cows from month 0 to 6 in milk. Serum insulin levels remained stable throughout lactation and were similar in both groups of cows. In conclusion, EPG around parturition may be a useful tool for identifying cows that will have a decrease in productivity due to parasite effects and would possibly benefit from an antiparasitic treatment. Besides, our results suggest that detrimental effect of parasites on milk production may be mediated by GH, IGF-I and prolactin serum levels.