Evidence For Viral Involvement Research Articles

Fibromatous lesions of antler velvet and haired skin in reindeer (Rangifer tarandus)

Fibromatous nodular lesions were observed on the antler skin of reindeer from four separate farms, and from the haired skin from a deer from a fifth farm. The aim of...

Recent advances in viral inner ear disorders

To highlight the recent advances in the understanding of the diagnosis and management of viral inner ear disorders. Congenital sensorineural hearing loss (cSNHL), sudden sensorineural hearing loss (SSNHL), Ménière's disease, and vestibular neuritis/viral labyrinthitis are discussed. Cytomegalovirus infection during pregnancy is an under-recognized cause of hearing loss and central nervous system disease amongst the general population. Prevention of maternal infection and treatment of affected newborns with ganciclovir are promising interventions. Recent evidence in SSNHL patients has resulted in recommendations against viral serology or the use of antivirals. There appears to be an increased risk of SSNHL in patients with comorbid hypertension and diabetes. The viral hypothesis of Ménière's disease remains unproven. In patients with an acute episode of vestibular neuritis, there is presently not sufficient evidence to support the routine use of corticosteroids or antiviral medications. cSNHL remains the most clearly defined of the viral inner ear disorders. The evidence for viral involvement in SSNHL, Ménière's disease, and vestibular neuritis is indirect and equivocal. This review highlights the recent advancements in the diagnosis and management of these disorders.

Vitamin E and Selenium Levels are Within Normal Range in Pigs Diagnosed with Mulberry Heart Disease and Evidence for Viral Involvement in the Syndrome is Lacking

SummaryMulberry heart disease (MHD) in pigs is characterized by lesions of acute haemorrhagic myocarditis and myocardial necrosis. The objectives of this study were to determine the levels of vitamin E and selenium and 13 other trace minerals in heart and liver tissues and to determine the prevalence of certain viral infections in heart tissues from MHD‐affected and MHD‐unaffected pigs and the vitamin E and selenium concentration in feed samples from selected farms with MHD. Based on the pathological examination, 114 pigs were separated into MHD lesion‐negative (L‐NEG) (n = 57) and MHD lesion‐positive (L‐POS) (n = 57) groups. Seventy‐three samples (40 L‐NEG and 33 L‐POS) were subjected to chemical analysis, and 66 (32 L‐NEG and 34 L‐POS) were subjected to PCR detection for viral pathogens. Lower (P < 0.05) levels of myocardial copper, lower (P < 0.05) levels of hepatic magnesium and higher (P < 0.05) levels of myocardial and hepatic sodium were detected in the L‐POS cases. Although lower (P < 0.05) levels of hepatic selenium were detected in L‐POS group, all were within the normal range. Analysis of feed samples (n = 22) revealed that selenium levels in all the samples were above the legal limit (0.3 ppm) for pigs. Vitamin E levels in all feed samples were above 20 IU/kg. Among the 66 pigs subjected to PCR detection, there were 19, 4, 13, 8, 2 and 1 animals positive for porcine circovirus type 2, porcine reproductive and respiratory syndrome virus, pan‐herpes virus, porcine enterovirus, pan‐pestivirus and porcine parvovirus, respectively. Clear evidence of viral association with L‐POS was lacking.

Viral Infections and Respiratory Disease in Dairy-Bred Calves

After salmonellosis respiratory disease probably remains the most important condition of market purchased dairy bred calves. Treatment rates for respiratory disease have been found to exceed 30% during the first three months of the rearing phase (1) and this disease is therefore responsible for significant losses in terms of animal performance, veterinary costs and labour irrespective of the implications for the welfare of the young calf.&#x0D; The association between respiratory virus infection and clinical respiratory disease has been demonstrated in weaned beef calves and in home reared dairy calves, but in calves less than three months of age there was little evidence of viral involvement (2 and 3). However disease monitoring on one calf rearing unit led to the observation that despite good response to antibiotic therapy, the outbreaks of sudden onset high morbidity respiratory disease seen in calves less than three months of age, had a possible viral aetiology. To explore this further the following study was carried out.

A perspective on human autoimmune thyroid disease: is there an abnormality of the target cell which predisposes to the disorder?

It has been suggested recently that autoimmunity could be regarded as a physiological response of the normal immune system to autoantigens caught up in an inflammatory response to viral or bacterial antigen expressed in the target tissue. Other theories to explain autoimmunity include molecular mimicry whereby a viral or microbial hapten similar to an autoantigen initiates the production of autoantibodies that cross react with an autoantigen, with a subsequent immune response reacting with autologous cell structures which are homologous with the particular microorganism. There has also been a suggestion that there may be a genetic abnormality of the target cell which is necessary for the initiation of autoimmune thyroid disease. The present review examines these proposals and provides evidence against an antigen-driven origin for autoimmune thyroid disease (AITD). Currently, there is no valid evidence for viral involvement, and likewise the evidence for molecular mimicry as an initiating factor does not hold up to scrutiny. While a genetic abnormality of the thyrocyte may be important in certain animal models of AITD, in the human there is no evidence for such an abnormality. Evidence that AITD is derived from a disturbance of immunoregulatory mechanisms has been documented elsewhere and would appear to be the most appropriate explanation for these disorders. The immunoregulatory disturbance itself may be related to an abnormality of the mechanism of specific antigen (i.e. normal autoantigen) presentation to appropriately induce T lymphocytes and that theory will require further illumination.

Myasthenia Gravis

The cause or causes of the autoimmune response to acetylcholine receptors (AChR) in myasthenia gravis (MG) may be difficult to discover. Thus far, no evidence of viral involvement has been found and arguments for bacterial involvement are not compelling. Nevertheless, it seems likely that an environmental factor is involved. Penicillamine is clearly one such factor. The association of thymoma with MG and the presence of autoantibodies to other muscle components suggest that the initiating mechanism or mechanisms involve more than the AChR per se. The rabies virus seems capable of using the AChR as a tissue-specific recognition site. Discovery of the autoimmune nature of MG was made possible by advances in molecular studies of the AChR. When AChRs were first purified from electric eels, it was observed that rabbits immunized with purified AChRs developed muscular weakness. Diagnosis of MG has improved with the availability of assays for antibodies to AChR. The pathological mechanisms of MG at the endplate are moderately well understood but they can certainly benefit from improvement in detail. It seems unlikely that major revelations will occur here. Advances in molecular studies of AChRs should permit a detailed understanding of the AChR as an immunogen and antigen.

Evidence for Viral Involvement in Murine and Human Mammary Adenocarcinoma

Particles which have several biochemical and biophysical properties diagnostic of ribonucleic acid (RNA) tumor viruses of animals have been isolated from specimens of human milk. The human particles have a density of 1.16 to 1.19 Gm. per ml., a RNA-directed deoxyribonucleic acid polymerase, and a 60–70S RNA. The quantity of particles in particular milk samples is determined by hybridization of the polyadenylic acid regions of their 60–70S RNA to radioactive polyribouridylic acid of known specific activity. A method involving molecular hybridization with radioactive DNA complementary to the RNA of the mouse mammary tumor virus was used to detect homologous RNA in both murine and human malignant breast tumors.