Differential attenuation of Marek's disease virus-induced tumours and late-Marek's disease virus-induced immunosuppression.

Marek's disease virus (MDV) is a herpesvirus that induces lymphoma and a variety of non-neoplastic syndromes in chickens. Furthermore, very virulent plus (vv+) MDVs induce a form of immunosuppression (late-MDV-IS) that might involve both neoplastic and non-neoplastic mechanisms. The objective of this study was to evaluate whether the attenuation of MDV-induced tumours and late-MDV-IS occurs simultaneously or can be dissociated. The immunosuppressive ability of three viruses derived from vv+ MDV strain 686 (wild-type 686, the somewhat attenuated molecular clone 686-BAC, and the nononcogenic molecular clone lacking the two copies of the oncogene meq 686-BACΔMEQ) was evaluated. Late-MDV-IS was evaluated indirectly by assessing the negative effect of MDV strains on the protection conferred by infectious laryngotracheitis (ILT) vaccines. Our results showed that the ability to induce late-MDV-IS was attenuated before the ability to induce tumours. Strain 686 induced both tumours and late-MDV-IS, 686-BAC induced tumours but did not induce late-MDV-IS and 686-BACΔMEQ did not induce either tumours or late-MDV-IS. Further comparison of strains 686 and 686-BAC revealed that strain 686 reduced the humoral immune responses to ILTV (1132 vs 2167) more severely, showed higher levels of meq transcripts (2.1E+09 vs 4.98E+8) and higher expression of MDV microRNAs (mdv1-miR-M4-5p and mdv1-miR-M2-3p) in the spleen, and further reduced the percentage of CD45+-MHC-I+splenocytes (13 vs32 %) compared to molecular clone 686-BAC. This study suggests that the immunosuppressive ability of MDV might follow a continuous spectrum and only the most virulent MDVs can overcome a certain threshold level and induce clinical MDV-IS in the ILT model.

Staphylococcus xylosus PCR-validated Decontamination of Murine Individually Ventilated Cage Racks and Air Handling Units by Using 'Active-Closed' Exposure to Vaporized Hydrogen Peroxide.

Vaporized hydrogen peroxide (VHP) is used to decontaminate clinical, biocontainment, and research animal rooms and equipment. To assist with its implementation in a murine facility, we developed a safe and effective method of VHP sterilization of IVC racks and air handling units (AHU). Safety of VHP decontamination was assessed by ensuring VHP levels dissipated to less than 1 ppm in the room prior to personnel reentry and inside the primary enclosure prior to the return of mice; this condition occurred at least 18 h after the VHP cycle. Efficacy of VHP sterilization was assessed by using chemical indicators, biologic indicators, and PCR testing for Staphylococcus xylosus, a commensal organism of murine skin and an opportunistic pathogen, which was present in 160 of 172 (93%) of specimens from occupied IVC racks and the interior surfaces of in-use AHU. Neither mechanized washing nor hand-sanitizing eradicated S. xylosus from equipment airway interiors, with 17% to 24% of specimens remaining PCR-positive for S. xylosus. 'Static-open' VHP exposure of sanitized equipment did not ensure its sterilization. In contrast, 'active-closed' VHP exposure, in which IVC racks were assembled, sealed, and connected to AHU set to the VHP cycle, increased the proportion of chemical indicators that detected sterilizing levels of VHP inside the assembled equipment, and significantly decreased PCR-detectable S. xylosus inside the equipment. Supplementing bulk steam sterilization of the primary enclosure with VHP sterilization of the secondary housing equipment during room change-outs may help to mitigate opportunistic agents that jeopardize studies involving immunodeficient strains.

Infection-derived lipids elicit an immune deficiency circuit in arthropods.

The insect immune deficiency (IMD) pathway resembles the tumour necrosis factor receptor network in mammals and senses diaminopimelic-type peptidoglycans present in Gram-negative bacteria. Whether unidentified chemical moieties activate the IMD signalling cascade remains unknown. Here, we show that infection-derived lipids 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG) and 1-palmitoyl-2-oleoyl diacylglycerol (PODAG) stimulate the IMD pathway of ticks. The tick IMD network protects against colonization by three distinct bacteria, that is the Lyme disease spirochete Borrelia burgdorferi and the rickettsial agents Anaplasma phagocytophilum and A. marginale. Cell signalling ensues in the absence of transmembrane peptidoglycan recognition proteins and the adaptor molecules Fas-associated protein with a death domain (FADD) and IMD. Conversely, biochemical interactions occur between x-linked inhibitor of apoptosis protein (XIAP), an E3 ubiquitin ligase, and the E2 conjugating enzyme Bendless. We propose the existence of two functionally distinct IMD networks, one in insects and another in ticks.

Effects of various starch feeding regimens on responses of dairy cows to intramammary lipopolysaccharide infusion.

Endotoxin tolerance (ET) can develop in mammals that have been challenged repeatedly with sublethal amounts of lipopolysaccharide (LPS). Previous research has shown that subclinical ruminal acidosis can increase circulating concentrations of LPS. We investigated whether ET would develop in Holstein cows that were subjected to chronic subacute ruminal acidosis (SARA) or acute SARA followed by intramammary infusion of LPS. Twenty-four cows, both primiparous and multiparous, were assigned to 8 blocks of 3 cows. Cows within blocks were randomly assigned to 1 of 3 treatments: (1) control (diet DM was 24% starch and 35% NDF), (2) high starch (formulated to induce chronic milk fat depression with 29% starch and 32% NDF), and (3) acidosis (designed to cause acute bouts of milk fat depression by short-term feeding of a diet with 32% starch, some of which came from wheat grain, and 30% NDF). Cows on the control and high-starch treatments were fed their respective diets throughout the 24-d trial. The acidosis cows were fed the control diet during most of the experiment, except during two 2-d bouts (d 10 and 11 and 17 and 18 of the experiment) in which a high-starch diet was fed. Cows on the high-starch and acidosis treatments produced milk fat with an altered fatty acid profile indicative of SARA (e.g., increased concentrations of specific trans, and odd-, and branched-chain fatty acids), but only cows on the high-starch treatment had milk fat depression. Concentrations of serum amyloid A were elevated in cows on the acidosis treatment, but did not differ between control and high-starch cows. On d 20 of the experiment, all cows were given an intramammary infusion of 10 µg of LPS into 1 mammary quarter 3h after morning milking. Milk yield and DMI decreased the day of the infusion, but the response was not affected by dietary treatment. No systemic indicators of ET were observed among treatments, but evidence of an ET response at the local level of the mammary gland was observed. Cows fed the control diet had higher concentrations of serum amyloid A in milk 12 and 24h postinfusion than did cows fed the high-starch diet and higher concentrations than cows on the acidosis treatment at 12h postinfusion. Our data suggest cows that experienced varying degrees of SARA (based on altered milk fatty acid profile) and subsequent experimental endotoxin mastitis experienced a blunted inflammatory response at the level of the mammary gland, but not a systemic reduction in some inflammatory mediators.

Bacterial infections in Myd88-deficient mice.

Three breeding colonies of Myd88(-/-) mice had a history of significant morbidity and mortality. Although strain-specific poor reproductive performance might explain neonatal death and dystocia, mice were found dead or required euthanasia because of moribundity, distended abdomen, head tilt, and seizures. Histopathology results included bacteremia, placentitis, metritis, peritonitis with abscess formation, and suppurative meningoencephalitis. Intralesional gram-negative coccobacilli were present, often in extremely high number. Cultures of samples of the cardiac blood of a mouse and from water-bottle sipper tubes provided to some affected mice grew Pseudomonas aeruginosa. In addition, affected tissues from 2 mice and feces from a third tested PCR-positive for P. aeruginosa. Although the mice had received autoclaved reverse-osmosis-purified drinking water, we suspect that the mice were inoculated with P. aeruginosa through contaminated sipper tubes. Because of the deficiency in most of the Toll-like receptor signaling pathways, these Myd88(-/-) mice were unlikely to have developed competitive innate and adaptive immune responses, resulting in bacterial infections. These clinical cases underscore the importance of understanding how genotype, phenotype and environment affect animal health. Sound husbandry and experimental practices are needed to prevent the exposure of immuno-deficient mice to pathogens.

An unmatched case controlled study of clinicopathologic abnormalities in dogs with Bartonella infection.

We compared clinicopathologic findings in dogs with Bartonella infection to Bartonella spp. negative dogs suspected of a vector-borne disease. Cases (n=47) and controls (n=93) were selected on the basis of positive or negative enrichment culture PCR results, respectively. Signalment, clinicopathologic findings and treatments were extracted from medical records. DNA sequencing identified Bartonella henselae (n=28, 59.6%), Bartonella vinsonii subsp. berkhoffii (n=20, 42.6%), Bartonella koehlerae (n=3, 6.4%), Bartonella volans-like (n=3, 6.4%) and Bartonella bovis (n=1, 2.1%). There were no significant differences in age, breed, size, sex or neuter status between cases and controls. Dogs infected with Bartonella sp. often had a history of weight loss [OR=2.82; 95% CI: 1.08-7.56] and were hypoglobulinemic [OR=4.26; 95% CI: 1.31-14.41]. With the exception of weight loss and hypoglobulinemia, clinicopathologic abnormalities in Bartonella-infected dogs in this study were similar to dogs suspected of other vector-borne infections.

Preliminary findings of a previously unrecognized porcine primary immunodeficiency disorder.

Weaned pigs from a line bred for increased feed efficiency were enrolled in a study of the role of host genes in the response to infection with Porcine Reproductive and Respiratory Syndrome Virus (PRRSV). Four of the pigs were euthanatized early in the study due to weight loss with illness and poor body condition; 2 pigs before PRRSV infection and the other 2 pigs approximately 2 weeks after virus inoculation. The 2 inoculated pigs failed to produce PRRSV-specific antibodies. Gross findings included pneumonia, absence of a detectable thymus, and small secondary lymphoid tissues. Histologically, lymph nodes, spleen, tonsils, and Peyer's patches were sparsely cellular with decreased to absent T and B lymphocytes.

Evolution of the immune system in the lower vertebrates.

The evolutionary emergence of vertebrates was accompanied by the invention of adaptive immunity. This is characterized by extraordinarily diverse repertoires of somatically assembled antigen receptors and the facility of antigen-specific memory, leading to more rapid and efficient secondary immune responses. Adaptive immunity emerged twice during early vertebrate evolution, once in the lineage leading to jawless fishes (such as lamprey and hagfish) and, independently, in the lineage leading to jawed vertebrates (comprising the overwhelming majority of extant vertebrates, from cartilaginous fishes to mammals). Recent findings on the immune systems of jawless and jawed fishes (here referred to as lower vertebrates) impact on the identification of general principles governing the structure and function of adaptive immunity and its coevolution with innate defenses. The discovery of conserved features of adaptive immunity will guide attempts to generate synthetic immunological functionalities and thus provide new avenues for intervening with faulty immune functions in humans.

Fell Pony syndrome: characterization of developmental hematopoiesis failure and associated gene expression profiles.

Fell Pony syndrome (FPS) is a fatal immunodeficiency that occurs in foals of the Fell Pony breed. Affected foals present with severe anemia, B cell lymphopenia, and opportunistic infections. Our objective was to conduct a prospective study of potential FPS-affected Fell Pony foals to establish clinical, immunological, and molecular parameters at birth and in the first few weeks of life. Complete blood counts, peripheral blood lymphocyte phenotyping, and serum immunoglobulin concentrations were determined for 3 FPS-affected foals, 49 unaffected foals, and 6 adult horses. In addition, cytology of bone marrow aspirates was performed sequentially in a subset of foals. At birth, the FPS-affected foals were not noticeably ill and had hematocrit and circulating B cell counts comparable to those of unaffected foals; however, over 6 weeks, values for both parameters steadily declined. A bone marrow aspirate from a 3-week-old FPS-affected foal revealed erythroid hyperplasia and concurrent erythroid and myeloid dysplasia, which progressed to a severe erythroid hypoplasia at 5 weeks of life. Immunohistochemical staining confirmed the paucity of B cells in primary and secondary lymphoid tissues. The mRNA expression of genes involved in B cell development, signaling, and maturation was investigated using qualitative and quantitative reverse transcriptase PCR (RT-PCR). Several genes, including CREB1, EP300, MYB, PAX5, and SPI1/PU.1, were sequenced from FPS-affected and unaffected foals. Our study presents evidence of fetal erythrocyte and B cell hematopoiesis with rapid postnatal development of anemia and B lymphopenia in FPS-affected foals. The transition between fetal/neonatal and adult-like hematopoiesis may be an important aspect of the pathogenesis of FPS.

Population screening of endangered horse breeds for the foal immunodeficiency syndrome mutation.

The Fell and Dales are UK pony breeds that have small populations and may be at risk from in-breeding and inherited diseases. Foal immunodeficiency syndrome (FIS) is a lethal inherited disease caused by the recessive mutation of a single gene, which affects both Fell and Dales ponies and potentially other breeds that have interbred with either of these. FIS, previously known as Fell pony syndrome, is characterised by progressive anaemia and severe B lymphocyte deficiency. The identification of the causal mutation for this disease led to the recent development of a DNA-based carrier test. In this study, the authors used this test to estimate the prevalence of the FIS mutation in the Fell and Dales populations, revealing that approximately 18 per cent of adult Dales ponies and 38 per cent of adult Fell ponies are carriers of the FIS defect. In addition, a study of five potential at-risk breeds was conducted to assess the transfer of the FIS defect into these populations. Of the 192 coloured ponies tested, two were confirmed as FIS carriers: No carriers were found among 210 Clydesdales, 208 Exmoor ponies, 161 Welsh section D, 49 part-bred Welsh section D and 183 Highland ponies.

Primary immunodeficiencies of dogs and cats.

Primary immunodeficiencies are congenital defects that affect formation or function of the immune system. Congenital immunodeficiency should be considered as a differential diagnosis for repeated infections in a young animal. Defects in the immune system may lead to complete or partial loss of immunity. Some animals with mild immunodeficiency can be managed with long-term antibiotic therapy.

Autoimmune diseases in small animals.

There are many autoimmune diseases recognized in humans; many of these have counterparts in companion animals. The diseases discussed in this article do not constitute the entire spectrum of autoimmune disease in these species. They are the common and better-described diseases of dogs and cats that have a well-documented autoimmune etiology. There are myriad autoimmune diseases that affect humans; similar diseases yet unrecognized in companion animals likely will be characterized in the future. The role of genetics in predisposition to autoimmunity is a common characteristic of these diseases in humans and animals. Likewise, the suggested role of environmental or infectious agents is another commonality between humans and their pets.

Biology and evolution of the endogenous koala retrovirus.

Although endogenous retroviruses are ubiquitous features of all mammalian genomes, the process of initial germ line invasion and subsequent inactivation from a pathogenic element has not yet been observed in a wild species. Koala retrovirus (KoRV) provides a unique opportunity to study this process of endogenisation in action as it still appears to be spreading through the koala population. Ongoing expression of the endogenous sequence and consequent high levels of viraemia have been linked to neoplasia and immunosuppression in koalas. This apparently recent invader of the koala genome shares a remarkably close sequence relationship with the pathogenic exogenous Gibbon ape leukaemia virus (GALV), and comparative analyses of KoRV and GALVare helping to shed light on how retroviruses in general adapt to a relatively benign or at least less pathogenic existence within a new host genome. (Part of a multi-author review).

Granulocytopenia associated with thymoma in a domestic shorthaired cat.

A 5-year-old, spayed female cat was referred because of a mass in the cranial mediastinum noted on thoracic radiographs. A thymoma was diagnosed following ultrasound and biopsy of the mass. Treatment was initiated with coarse-fraction radiation therapy using external-beam therapy (four fractions of 5 Gy). The mass responded, but granulocytopenia developed. Bone marrow examination showed a myeloid to erythroid ratio of approximately 1:1, with a left shift within the myeloid line. These findings, as well as the lack of toxic changes within the peripheral blood neutrophils, suggested immune-mediated destruction of peripheral granulocytes. Immune suppression with prednisone and cyclosporine was instituted. After 7 weeks, the neutrophil count returned to normal. The tumor was removed, and cyclosporine was reduced and eventually discontinued 3 weeks postsurgery.