Analysis of the quantity of antiviral antibodies from mink infected with different Aleutian disease virus strains

Mink persistently infected with Aleutian disease virus (ADV) develop hypergammaglobulinaemia and immune complex disease. Radiolabelled antibodies from mink infected with ADV-G, DK, Pullman , and Utah I strains of ADV were reacted against all four ADV strains in radioimmunoassay (RIA). The amount of anti-ADV antibody in two equally hypergammaglobulinaemic serum pools varied from 13% (anti- Pullman ) to 57% (anti-Utah I). Serum pools from two other sources (anti-DK and anti-ADV-G), although less hypergammaglobulinaemic , had 5% and 13%, respectively, indicating that 43-95% of the Ig in the sera of mink with AD was not specific antibody to ADV structural antigens. The possibility of a general polyclonal activation of the humoral immune system is being discussed. Comparison of plateau RIA binding levels for the four serum pools against the four viral antigens suggested three patterns of reactivity: DK and Utah I reacted similarly, but Pullman and ADV-G reacted serologically different.

Mink with Aleutian disease have high-affinity antiviral antibodies

Mink persistently infected with Aleutian disease virus (ADV) develop plasmacytosis (hypergammaglobulinaemia) and immune complex disease. Mink of different colour phases were infected with different strains of ADV and bled at different times after infection. The average antibody affinities (Kav) were measured in the sera and found to fall in the range of 2 X 10(9) - 2 X 10(10) M-1, thus indicating good-quality antibodies. In sera of non-Aleutian genotype mink a decline in Kav during development of plasmacytosis was observed. Moreover, the antibody heterogeneity (alpha values) tended to decrease during the disease progress. In contrast, the Kav values in sera of infected Aleutian genotype mink remained relatively high after hypergammaglobulinaemia developed, and the antibody heterogeneity for certain of the mink sera indicated restricted heterogeneity (high alpha values). In agreement with the clonal selection theory, low virus burden (for instance, during infection with a low-virulence ADV strain) generated relatively higher affinity antibodies than a high virus burden for instance, the highly virulent Utah I strain of ADV). Furthermore, antibodies present in low concentration were of higher affinity than antibodies present in high concentrations. The relatively high affinity antibodies found in this study indicate that if the immune complex disease seen in AD is caused by virus-anti-virus antibodies, good-quality antibodies are likely to be responsible for the pathological findings.

Immune complexes in Aleutian disease: demonstration of antibody on isolated virus

The specific binding of Staphylococcal protein A for mammalian immunoglobulin G was used to demonstrate IgG associated with Aleutian disease virus (ADV) when isolated from infected mink tissues. Protein A specifically bound to mink serum Ig with no reaction with other serum or tissue proteins. Protein A labeled with 131Iodine reacted with crude virus preparations but not with virus that had been purified by freon extraction to the point where it became reactive with antibody by counterimmunoelectrophoresis. Binding to purified ADV was restored when the purified virus was first reacted with antibody. Results of urea treatment indicated this as an alternative method for isolation of ADV free from antibody.

Serological analyses of different mink Aleutian disease virus strains

Four different isolates of Aleutian disease virus have been compared electrophoretically and serologically. These were the DK and Utah 1 isolates, known as highly virulent strains, the Pullman isolate, known as a low virulent strain and the avirulent ADV-G isolate, which is the only strain grown in cell culture. ADV-G was shown to migrate in agarose electrophoresis 22 per cent slower than the other strains. Several murine monoclonal antibodies were prepared against each of the isolates. Each one reacted with all 4 of the isolates, but a few showed higher affinity for some of the isolates. Competitive RIA analyses were also performed, and these studies indicated some serological differences between the 4 strains. It is concluded that ADV-G polypeptides are chemically different but immunologically cross-reacting with the polypeptides present on the field ADV strains. It is suggested that the small serological differences seen between the field strains might be caused by slightly different in vivo proteolytic degradation of the viral capsid proteins and thus might not be taken as an indication of strain variation.

Immunoglobulin classes of Aleutian disease virus antibody

Aleutian disease virus (ADV) persistently infects mink and causes marked hypergammaglobulinemia. Immunoglobulin class-specific antisera were used to define the total immunoglobulin of each class by radial immunodiffusion and the immunoglobulin class of ADV-specific antibody by immunofluorescence in experimentally and naturally infected mink. Electrophoretic gamma globulin closely reflects the immunoglobulin G (IgG) level in mink, and the majority of the increased immunoglobulin and ADV antibody in infected mink is IgG. IgM becomes elevated within 6 days after infection, reaches peak levels by 15 to 18 days, and returns to normal by 60 days after infection. The first ADV antibody demonstrable is IgM, and most mink have virus-specific IgM antibody for at least 85 days postinfection. Serum IgA levels in normal mink are not normally distributed, and ADV infection causes a marked elevation of IgA. Low levels of ADV-specific IgA antibody can be shown throughout the course of infection. Failure of large amounts of virus-specific IgG antibody to inhibit the reaction of virus-specific IgM and IgA antibodies suggests that the various classes of antibodies are directed against spatially different antigenic determinants. The IgM and IgA were shown not to be rheumatoid factors.

Borna disease of horses. An immunohistological and virological study of naturally infected animals

The brains of eight horses that had suffered from natural Borna disease were examined with virologic, immunohistological, and electron-microscopic methods. All brains harbored infectious virus as shown by inoculation of experimental animals. Regional assessment of the infectivity exhibited the highest titers in the hippocampus and piriform cortex and the lowest in the cerebellum. Conventional histology yielded pathologic alterations very similar to those of the classical description of the disease. Immunohistology demonstrated the highest amounts of Borna disease virus-specific antigen in the nuclei of neurons. In the perikarya, dendrites, and axons smaller amounts of antigen were found. A comparison of the antigen distribution with the inflammatory reaction established a high concordance of these two parameters. The presence of virus-specific antigen seems to trigger the exsudation of inflammatory cells, which reflect the extension of the infectious process. Heavy inflammatory exsudates in the white matter underlying diseased cortical areas can be explained by the axonal presence of virus-specific antigen. Virus particles could not be demonstrated with the electron microscope. The most significant findings at the ultrastructural level were stacks of fine filaments, adhering closely to cytoplasmic cisterns. These structures might be related to virus components or might be involved in virus morphogenesis.

Sensitive radioimmune assay for measuring Aleutian disease virus antigen and antibody

A solid-phase, one-step radioimmune assay was developed which could detect as little as 0.02 microliter of a standard Aleutian disease virus antigen preparation, approximately 3.2 ng of viral protein. Virus antigen was measured in different mink organs and cell types during experimental intraperitoneal infection. The gut and kidney were the first organs in which virus antigen could be detected (day 3 to 6 after infection). On day 6 or later virus antigen was found in spleen, liver, kidney, lymph nodes, peritoneal exudate, and bone marrow cells. With inhibition of antigen binding, a radioimmune assay was developed for antibody detection. Viral antibodies could be detected as early as 3 days after infection. Antibody titers from 1/10(5) to more than 1/10(6) were found in plasmacytotic mink. When the sensitivity of the antibody radioimmune assay was compared with that of other known methods for anti-Aleutian disease virus quantitation, the radioimmune assay was considerably more sensitive, detecting as little as 5 ng of antibody.

Autoimmunity in Aleutian disease: contribution of antiviral and anti-DNA antibody to hypergammaglobulinemia

The contributions to Aleutian disease gammopathy of specific antiviral antibody and an autoimmune component, anti-DNA antibody, were studied with pastel ranch mink naturally infected with Aleutian disease virus. Specific antibody activities were determined by countercurrent immunoelectrophoresis and radioimmune assay, respectively. Gamma globulin levels (percent gamma) were determined by serum electrophoresis. Within an infected mink population, it was possible to predict the level of gammopathy from measurement of the two antibody levels. For the mink serum samples used, there was better correlation between anti-DNA antibody levels and total serum immunoglobulin than between anti-Aleutian disease virus antibody titers and percent gamma. With serum samples taken over a 2-week interval, significant increases were measured in anti-DNA antibody and percent gamma. Increases in anti-Aleutian disease virus titers during this period were not significant. The results suggest that the continuing increases in serum immunoglobulin in Aleutian disease virus-infected mink are due to both a specific antiviral response and an autoimmune response, as reflected in generation of anti-DNA antibody.

Isolation of virus and antibody containing immune complexes from mink with Aleutian disease by affinity chromatography of equine complement clq

Affinity chromatography on immobilized equine complement Clq was used for the isolation of complement-binding immune complexes in sera of mink infected with Aleutian disease virus. Immune complexes were isolated and quantitated from 4 of 5 infected mink, as early as 2 weeks after infection and before hypergammaglobulinemia had appeared. The quantity of immunoglobulin G in these immune complexes ranged from 180 to 370 micrograms/ml serum. There were no Clq-binding immune complexes found in mink which were negative for Aleutian disease antibody. Using 125I-labeled BSA-anti-BSA complexes, we demonstrated that the affinity columns bound selectively immune complexes which had formed in antibody excess, whereas immune complexes in antigen excess were not bound. By neutralization of sensitized virus with anti-mink IgG serum, non Clq-binding immune complexes were also detected, which indicates that circulating immune complexes in persistently infected mink are heterogeneous as far as their reactivity with equine Clq is concerned.

Pleural effusion disease in rabbits. Properties of the aetiological agent

The size and heat sensitivity of Pleural effusion disease (PED) agent or virus (PEDV) propagated in rabbits were examined. The infectious particles were estimated to be between 25 and 50 nm by filtration. Residual infectivity of infectious serum was 0.1 per cent after heating at 56 degrees C for 4 hours. PEDV and the Stockholm agent appeared identical concerning pathogenic and immunogenic properties by infection experiments and protection tests in rabbits. Two of the three PEDV isolates were less pathogenic but appeared immunogenically identical to PEDV. The third isolate, obtained from the laboratory, which several years previously had supplied material for demonstration of the Stockholm agent, differed from PEDV in pathogenic and immunogenic properties. Serological examinations of paired rabbit sera did not indicate any antigenic relationship between PEDV and representative members of the two mammalian coronavirus antigenic groups. It is concluded that the aetiological agent of PED is a virus not belonging to the coronaviridae.

Mitogen- and viral antigen-induced transformation of lymphocytes from normal mink and from mink with progressive or nonprogressive Aleutian disease

Peripheral blood lymphocytes (PBL) from mink with progressive Aleutian disease (AD) were shown to be significantly less responsive to phytohemagglutinin, concanavalin A, and pokeweed mitogen than were PBL from normal mink and from mink with a nonprogressive form of AD. Response to the virus of AD was significantly greater in PBL cultures from mink with nonprogressive AD than in those from normal mink or mink with progressive AD. After experimental infection with AD virus, mink PBL were responsive to viral antigen only transiently. These findings suggest that lymphocyte responsiveness as indicated by transformation induced by mitogens or viral antigen may be an important aspect of host response to infection with the parvovirus of AD.

Norwalk virus gastroenteritis in volunteers consuming depurated oysters

Following the widespread outbreaks of oyster-associated gastroenteritis which occurred throughout Australia in 1978, several programmes were introduced to minimise the occurrence of further outbreaks. One programme included the depuration (purification) of oysters and the use of human volunteers to test-consume samples from batches of depurated oysters before their sale to the public. Oysters from the Georges River and Brisbane Waters were test-consumed from December, 1978, to August, 1979. None of the volunteers was ill after consuming Brisbane Waters oysters but 52 reported ill after eating Georges River oysters. The predominant symptoms were nausea, vomiting and diarrhoea with an average incubation period of 42 hours. Recovery was usually complete in 36-48 hours. Of the 52 illnesses reported 31 (60%) occurred in two particular weeks ending July 1st and 22nd when rates of 18.3% and 7.8% were reported. The average illness rate for the remainder of the period under study was only 1%. Norwalk virus was found in 8 of 25 (32%) stools, and antibody increases demonstrated in seven of ten paired sera, giving an overall diagnostic rate for Norwalk infection of 37.0% for these two peak periods. Heavy rain preceded these two weeks in which the illnesses occurred. No evidence of Norwalk infection was found at any other time. These studies confirmed the epidemiological findings of the major outbreak of gastroenteritis in 1978, and showed that only Georges River oysters caused Norwalk virus infections and that depuration as carried out in 1979 was not entirely satisfactory.

The 33- to 39-nm virus-like particles, tentatively designed as Sapporo agent, associated with an outbreak of acute gastroenteritis

An outbreak of nonbacterial gastroenteritis occurred in an orphanage in December 1979. Of 54 residents, 43 were affected with acute gastroenteritis. Diarrhea was the commonest symptom. The 33- to 39-nm virus-like particles, tentatively designated as Sapporo agent, were detected in 17 (48.6%) of the patients' 35 fecal specimens. Morphologically, it was difficult to distinguish the Sapporo agent from other agents without geometrical pattern of the surface. Antigenically, the Sapporo agent related to the Otofuke agent detected in an outbreak of the institution for mentally retarded adults and also to the SRV ;76 detected in familial cases of infectious gastroenteritis. The Sapporo agent might belong to a new group of those gastroenteritis viruses which were larger in size than the Norwalk virus group.

Oyster-associated gastroenteritis in Australia: the detection of Norwalk virus and its antibody by immune electron microscopy and radioimmunoassay

Following widespread outbreaks of oyster-associated gastroenteritis in Australia during 1978 in which Norwalk virus was implicated as the causative agent, collaborative studies were undertaken between laboratories in Australia and the United States to confirm the etiology. Immune electron microscopy (IEM) techniques were used in Australia and radioimmunoassay (RIA) methods in the United States. Norwalk virus was detected by IEM in seven of 15 faecal samples, and four were positive by RIA. A much better correlation was found with antibody determinations. Both methods demonstrated significant increases in antibody to Norwalk virus in 22 of 30 sets (73%) of "acute" and "convalescent" sera, confirming that Norwalk virus was responsible for the majority of cases. It is significant that the RIA serology was determined using Norwalk antigen originating in the United States and the IEM serology was determined using 27--30-nm particles originating in Australia.

Immune response and prevalence of antibody to Norwalk enteritis virus as determined by radioimmunoassay

A solid-phase microtiter radioimmunoassay was established for the detection of Norwalk virus and its antibody, with clinical materials from human volunteers previously studied in Massachusetts as reagents. A study of 308 Massachusetts residents showed that serum antibody to Norwalk agent was rarely present during childhood but was detectable in approximately 50% of adults. All volunteers inoculated with Norwalk virus who developed illness seroconverted (10/10), whereas only one-third (5/15) of nonill volunteers seroconverted (P = 0.0009). The 10 nonill, nonseroconverting subjects had undetectable to low preexisting antibody levels. Paradoxically, 10/13 subjects with preexisting antibody became ill, whereas 17/25 lacking antibody did not (P = 0.009). All 3 subjects with preexisting anti-Norwalk radioimmunoassay blocking activity in duodenal intraluminal fluids became ill, whereas only 5/11 lacking such activity developed illness (P = 0.15). These data further support the unique concept that some individuals are susceptible to repeated infections with this agent, whereas others are incapable of developing infection.

Prevalence of antibody to the Norwalk virus in various countries

Serum samples from children and adults from several countries were tested by radioimmunoassay for antibody to the Norwalk virus. Antibody was commonly found in adults from all the countries tested. Antibody appears to be acquired more rapidly in children from underdeveloped countries than in children from the United States.

Biophysical properties of a non-cultivable 29-nm enteric virus

A 29 nm non-cultivable virus (NCV) was detected in faecal extracts from children hospitalized for gastroenteritis. The NCV had a density of 1.35 g/ml in glycerol-potassium tartrate density gradients and was resistant to degradation by proteolytic enzymes, non-ionic detergents and pH extremes. The surface of these virus particles had knob-like projections which appeared to have a symmetrical arrangement. When heated to 56 degrees C, the virus was completely degraded to soluble components which could not be seen by electron microscopy.

Antibodies to viral gastroenteritis viruses in Crohn's disease

Antibody prevalence and titer to rotavirus and Norwalk virus were studied in Crohn's disease patients and in age-, sex-, and time-matched controls. There were no significant antibody differences between the groups studied.

Isolation of a virus strain from Argas persicus ticks

A previously undescribed virus was isolated from Argas persicus ticks collected on sentinel chicken in western Slovakia. The strain was lethal for suckling mice only after intracerebral inoculation. No symptoms were induced in adult mice. The virus strain was insensitive to sodium deoxycholate and resistant to ether treatment. An antigen prepared from the virus did not agglutinate goose or human O erythrocytes. The single strain obtained in 1976 appeared to be untrelated to a large number of known arboviruses when tested by the complement-fixation reaction.

Astrovirus gastroenteritis age distribution of antibody

Astrovirus antibody was detected by immunofluorescence using infected primary human embryo kidney cultures as antigen. Of 87 Oxford children aged 0--10 years, only 7% in the 6 to 12-month-old group had antibody. The percentage of children having evidence of past infection rose progressively in the 1--4 age range and 75% of the 5 to 10-year-old group possessed astrovirus antibody. Fifty-four (77%) of a group of 70 young adults likewise had antibody.

Norwalk agent-like particles associated with gastroenteritis in human beings

Currently, 6 agents of viral gastroenteritis with properties similar to the Norwalk agent have been described. These are the Hawaii, Montgomery County, W, Ditchling, and Cockle agents, as well as the Norwalk agent. These agents are 25 to 27 nm in diameter, are nonenveloped, and have a buoyant density of 1.38 to 1.40 g/cc in CsCl. Multiple antigenic types exist among these agents. These particles have been detected by immune electron microscopy in feces of acutely ill patients. None has been successfully cultivated in vitro, and suitable animal models of disease do not exist. Studies in volunteers indicate that acute infection is associated with a reversible histopathologic change in the jejunal mucosa and with transient malabsorption. Pathogenesis of these changes remains unknown. Other similar agents will likely emerge from ongoing studies.