Humoral immune responses to phocine herpesvirus-1 in Pacific harbor seals (Phoca vitulina richardsii) during an outbreak of clinical disease

Infection with phocine herpesvirus type-1 (PHV-1) has been associated with morbidity and high mortality in neonatal harbor seals (Phoca vitulina). A PHV-1 specific indirect enzyme linked immunosorbent assay (ELISA) was developed to sequentially measure the serological status of 106 harbor seal neonates admitted to a Pacific coast rehabilitation center (total number of sera tested was 371). Early in the season (February-April), the majority of pups had low serum levels of PHV-1 specific antibody. A dramatic increase in PHV-1 specific antibody, involving the majority of hospitalized pups, was observed during a 4-week period in May. This coincided with a high incidence of PHV-1 associated adrenal lesions and mortality. Although there was overall agreement between the timing of seroconversion to PHV-1 and histological evidence of PHV-1 infection, 82.4% of individual pups with adrenalitis had no evidence of a humoral response to PHV-1 at the time of their death. This suggests either a rapid disease course, or an inability to develop a humoral response in some neonatal seals.     

Detection of phocine distemper virus using the polymerase chain reaction

During the fatal seal epizootics in the North and Baltic Seas in summer 1988 a virus was isolated which was shown to be the causal agent. It was subsequently classified as morbillivirus by neutralization assays, reaction with monoclonal antibodies and nucleic acid hybridization studies. The virus (tentatively called Phocine Distemper Virus, PDV) is difficult to grow in culture making rapid diagnosis difficult. We have used the Polymerase Chain Reaction (PCR) as an alternative and fast method to detect the presence of virus-specific nucleic acid and we describe here the amplification of cell culture derived PDV RNA in a "one-tube" reaction using heterologous (Rinderpest Virus cDNA derived) F gene primers. The resulting 370 bp DNA fragment was shown to be morbillivirus derived by Southern blot hybridization using cloned RPV F gene as probe.     

Humoral immune responses of cats to feline infectious peritonitis virus infection.

Immunoperoxidase antibody (IPA) method as a titrating method of feline infectious peritonitis (FIP) virus (FIPV) was developed for titrating antibody to FIPV (IPA-titer). By this method the immune responses of the cats that had been infected with FIPV, were traced. The infected cats could be grouped into three types by their immune response to FIPV and clinical appearances. Type I cats lived for a long time, formed a major group among infected cats, had 160 to 1 x 10(4) IPA-titers, and showed healthy appearances without any changes both on autopsy and histopathologically. From among type I cats, type II cats appeared sporadically with rapid elevation of IPA titers to 3.2 x 10(5) and showing clinical signs of FIP, and died. Type III cats lived healthily for a long time with gradual elevation of IPA-titers to a plateau of about 1 x 10(5), then showed neuronal disorder of hind leg paralysis with the descending IPA-titers to 2 x 10(4), and died. Thus, typical FIP appeared as a hyper-immune disease. Other related problems are discussed.     

Antiserum raised in pigs against canine distemper virus and its utility in diagnostic procedures for morbillivirus infections (canine distemper, phocine distemper, rinderpest)

Antiserum against canine distemper virus (CDV) was raised in pigs by intranasal inoculation with CDV strains CND65 and ROCKBORN. Immunoglobulin fractions were conjugated with horseradish peroxidase. Peroxidase-conjugated anti-CDV immunoglobulin preparations were used for the detection and titration of CDV, seal-derived (phocine) distemper virus (PDV) and rinderpest virus (RPV) in Vero cell cultures. For the detection and titration of corresponding neutralizing antibodies a direct neutralizing peroxidase-linked antibody (NPLA) assay was established. The results were compared with those obtained with the conventional microtitre neutralization test (MNT) based on CPE reading. In addition the sensitivity of an indirect peroxidase-linked antibody (PLA) assay was tested in parallel with that of the NPLA assay using sera obtained from CDV-immunized pigs.     

Investigations on course and outcome of phocine distemper virus infection in harbour seals (Phoca vitulina) exposed to polychlorinated biphenyls. Virological and serological investigations.

The influence of polychlorinated biphenyls (PCBs) on phocine distemper virus (PDV) infections in harbour seals (Phoca vitulina) was studied. Six out of ten seals had been conditioned with a defined mixture of PCB-congeners for several weeks. Following exposure to the cell culture-propagated PDV isolate 2558/Han 88 the complete clinical picture of "1988 seal plague" was provoked in all ten seals inoculated. Four out of six PCB-conditioned seals and two out of four seals not loaded with PCBs succumbed to the infection within three weeks post inoculation. With regard to the clinical course, duration of cell-associated viremia, PDV-antigen distribution in tissues of fatally infected seals and the humoral immune response to PDV no differences between PCB-loaded and unloaded seals were recognized. Evidence was obtained that the pathogenesis of experimental PDV-infection in harbour seals shares some features with those of canine distemper in terrestrial carnivores. In contrast, however, to experimental distemper infection of gnotobiotic dogs prompt development of high titres of PDV-specific IgG did not correlate with recovery from infection.     

Humoral and cellular responses in calves experimentally infected with bovine leukemia virus (BLV)

In order to elucidate whether infection by Bovine Leukemia Virus (BLV) might induce an immunodeficient state, we inoculated sixteen calves with BLV. The calves were followed up for two years and were tested for humoral and cellular responses using various parameters, namely the appearance of antibodies to the BLV antigens, the changes in the numbers of lymphocytes involved, and the ratio between the two main populations of lymphocytes. Antibodies to the BLV antigens were of both the IgG and the IgM classes of immunoglobulins. The levels of antibodies of the IgM class were higher than those of IgG. There was a temporary decrease of reactive antibodies to the BLV antigens, to below detectable levels, during the 14-24 weeks post infection. A significant decrease in the level of plasma IgM was found in all BLV infected calves exhibiting lymphocytosis, while the level of IgG in the plasma of all experimental calves did not diverge significantly from the initial values, throughout the experiment. BLV infection was followed by lymphocytosis of B-cells in most infected calves, which persisted for the whole course of the experiment, while a decrease in the population of T-cells in peripheral blood was observed for a period of several months in all infected calves.     

Humoral immune response against Borna disease virus (BDV) in experimentally and naturally infected cats

In order to investigate the peripheral and intracerebral humoral immune response against Borna disease virus (BDV) in cats, serum and cerebrospinal fluid (CSF) samples from experimentally and naturally BDV-infected cats were analysed in two different test systems (indirect enzyme-linked immunosorbent assay and indirect immunofluorescent test). The experimentally infected cats developed high antibody titres against the major immunogenic BDV-proteins, p24 and p40. In contrast, the naturally infected cats showed a comparatively weak humoral immune response. The experimentally infected cats were inoculated with either BDV laboratory strain V or a feline BDV-isolate. Some differences existed between the two groups of cats. The former group developed a higher response against p40, whereas the latter group showed, beside the p40-response, a more pronounced p24-response, similar to the situation in the naturally infected cats.     

Quantitative analysis of the 2002 phocine distemper epidemic in the Netherlands

Phocine distemper virus (PDV) caused thousands of deaths among harbor seals (Phoca vitulina) from the North Sea in 1988 and 2002. To examine the effects of different factors on the pathology of phocine distemper, we performed necropsies and laboratory analyses on 369 harbor seals that stranded along the Dutch coast during the 2002 PDV epidemic. Diagnostic tests for morbillivirus infection indicated a differential temporal presence of morbillivirus in lung and brain. Seals of 3 years or older were significantly more often IgG positive than younger seals. The most frequent lesions in PDV cases were bronchopneumonia, broncho-interstitial pneumonia, and interstitial emphysema. Extra-thoracic emphysema was rare in <1-year-olds compared with older seals, even though severe pneumonia was more common. PDV cases generally had empty stomachs and less blubber than by-caught seals from before the epidemic. In PDV cases involving older animals, lung, kidney, and adrenal weights were significantly increased. Bordetella bronchiseptica was isolated from lungs in two thirds of the PDV cases examined. Our results indicate that brain should be included among the tissues tested for PDV by RT-PCR; that either phocine distemper has a longer duration in older seals or that there are age-related differences in immunity and organ development; that dehydration could play a role in the course and outcome of phocine distemper; and that bacterial coinfections in lungs are more frequent in PDV cases than gross lesions suggest. These results illustrate how quantitative analysis of pathology data from such epidemics can improve understanding of the causative disease.     

Effects of chloramphenicol on the development of immune responses to canine distemper virus in Beagle pups

The effect of oral chloramphenicol (CHPC) on the development of immune responses to canine distemper virus (CDV) in Beagle pups was studied. Dogs were treated with CHPC for 14 days at a dose of 50 mg/kg, three times a day. Hematologic changes in CHPC-treated dogs included: polychromasia, anisocytosis, and target cell formation of red blood cells concurrent with vacuolation of lymphocytes and basophilic granule formation in neutrophils. Dogs given this therapy showed normal in vivo and in vitro immune responses after CDV vaccination and survived a virulent CDV challenge, whereas untreated, unvaccinated dogs became ill or died after challenge exposure. The results of this study indicate that CHPC therapy does not interfere with either the prechallenge immune response to attenuated viral antigen or the efficient immune mechanisms invoked during virulent virus challenge.     

Effects of prednisolone on the development of immune responses to canine distemper virus in beagle pups

Effects of oral prednisolone (OP) on the development of immune responses of Beagle pups to canine distemper virus (CDV) were studied. Dogs were treated with OP for 21 days, twice a day for the first 7 days, once a day for the next 7 days, and on alternate days for the last 7 days. Dogs given dosages of OP (1 mg/kg and 10 mg/kg) showed a normal in vivo immunogenic response after CDV vaccination and survived a virulent CDV challenge exposure, whereas non-treated, nonvaccinated dogs became ill or died after challenge exposure. The most marked effect of corticosteroid treatment on the immune system was the graded phytoimmunosuppressive effect upon the lymphocyte blast transformation test.     

Humoral immunity in cats infected with feline immunodeficiency virus or leukaemia virus

The humoral antibody responses of 82 domestic cats to the common commensal bacteria Pasteurella multocida and Staphylococcus aureus were measured by an indirect immunofluorescence assay to give a subjective quantification of specific IgG in serum. There was no significant difference in specific serum IgG levels between sick cats which tested antibody-positive to feline immunodeficiency virus or antigen-positive to feline leukaemia virus and sick, virus-negative cats. This finding suggested that there was no change in immune status, as measured by this method, in both feline leukemia and feline immunodeficiency virus infections, although, based on clinical signs shown by the virus-positive cats, overall immunosuppression was indicated. Feline immunodeficiency virus and feline leukemia virus infection may have an effect on cellular immunity, as is the case with human immunodeficiency virus.     

柔嫩艾美耳球虫（Eimeria tenella）感染鸡IgG生成细胞及血清IgG变化

利用免疫组化技术和Dot-ELISA，分别检测了雏鸡初次感染柔嫩艾美耳球虫（E.tenella)后，盲肠局部和免疫器官中IgG生成细胞数的动态变化、循环血液中特异性IgG水平的动态变化、雏鸡母源抗体的动态变化以及不同抗体水平雏鸡的抗球虫能力。结果表明，（1）感染后2-3d，盲肠粘膜、脾脏、法氏囊、肓肠扁桃体中的IgG生成细胞即开始增殖，9-12d达峰值，随后开始下降，盲肠扁桃体中IgG生成细胞数在22d时仍高于对照组；（2）感染后6d即可在循环血液中检测到特异性IgG，18d达峰值，30d降至感染后7d时的水平；（3）特异性母源抗体IgG水平高的雏鸡，抗球虫能力高，二者呈明显的正相关。     

Immunohistochemical investigation of cerebellum in dogs infected with canine distemper virus

The cerebella of 21 dogs with canine distemper virus (CDV) infection and four normal dogs were examined histopathologically and immunohistochemically. Cerebella of CDV-infected dogs showed nonsuppurative demyelinating encephalomyelitis, classified as acute, subacute or chronic. Immunolocalisation of CDV antigen also confirmed the infection. Tissues were examined for co-localisation of the CDV antigen with either an astrocyte-specific marker, glial fibrillary acidic protein (GFAP), or an oligodendrocyte-specific marker, galactocerebroside (GalC). Immunoreactive cells were counted in demyelinating areas of the white matter. The number of astrocytes (GFAP positive) was significantly (p < 0.05) higher in CDV-infected dogs compared to controls. In contrast, the number of oligodendrocytes (GalC positive) was significantly (p < 0.001) lower in CDV-infected dogs and was much lower in chronic cases (p < 0.05). Approximately 41% of astrocytes and 17% of oligodendrocytes were immunoreactive for CDV. The ratio of CDV-infected oligodendrocytes and astrocytes remained almost constant during the progression of the disease (P > 0.05). In conclusion, CDV infects both astrocytes and oligodendrocytes. The gradual loss of oligodendrocytes is most likely responsible for the progressive demyelination in CDV infection. Astrocytosis in CDV infection should be further investigated if it occurs to stimulate oligodendrocytes for myelin production to compensate for the loss or to induce oligodendrocyte degeneration.     

Humoral antibody response in animals infected with virulent rinderpest virus

Summary Humoral antibody responses in cattle or rabbits infected with virulent rinderpest virus or lapinised rinderpest virus respectively were assessed. Rinderpest specific antibodies could be first detected 6 days post-infection. No correlation could be established between antibody response and the course of the disease in infected animals during the early stages of infection. The animals with fatal infection either did not respond or had a transient antibody response. A gradual increase in antibody titre from 7 days post-infection was observed in animals which ultimately recovered.

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Respuesta De Anticuerpos Humorales En Animales Infectados Con Virus Virulento De Rinderpest

Resumen Se llevó a cabo un estudio tendiente a captar la respuesta de anticuerpos humorales en bovinos o conejos infectados con virus virulento de rinderpest o virus lapinizado de rinderpest, respectivamente. Los anticuerpos específicos de rinderpest fueron detectados a partir de los 6 días despues de la inoculación. No se pudo establecer correlación entre la respuesta de anticuerpos y el curso de la enfermedad en animales infectados, durante los estadíos iniciales de la enfermedad. Los animales con infecciones fatales o no respondieron o tuvieron una respuesta humoral débil. Los animales que se recuperaron presentaron un alza progresiva en el nivel de anticuerpos desde los 7 días después de la infección.

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Response Immunitaire Humorale Chez Des Animaux Infectes Par Le Virus De La Peste Bovine

Résumé Les réponses immunitaires de bovines ou lapins infectés respectivement par le virus de la peste bovine virulent ou lapinisé ont été évaluées. Des anticorps spécifiques contre la peste bovine ont pu être décelés 6 jours après l'infection. Aucune corrélation n'a pu être établie entre la réponse immunitaire et l'évolution de la maladie chez les animaux durant les premiers stades de l'infection. Les animaux n'ayant pas survécu soit n'ont pas développé une réponse immunitaire soit l'on présentée mais de façon transitoire. Une augmentation graduelle de taux d'anticorps à partir du 7e jour après l'infection a été observée chez les animaux qui ont fini par guérir.

     

Humoral immune responses to chicken infectious anemia virus in three strains of chickens in a closed flock

This is a comparative study on seroconversion to chicken infectious anemia virus (CIAV) in a closed flock of specific-pathogen-free chickens undergoing a natural outbreak and after vaccination of some of these flocks with a commercial, live vaccine. The N2a strain (B21B21 haplotype) had the highest seroconversion after natural infection (94%) or vaccination (100%), followed by the P2a strain (B19B19) at 75%-82% seroconversion after natural infection and 85% seroconversion after vaccination. The S13 (B13B13) chickens were 26% seropositive after natural infection and 75% seropositive after vaccination. N2a chickens with polymerase chain reaction (PCR)-positive tissues were 97% seropositive compared to 80%-83% PCR-positive and seropositive for the P2a chickens and only 8% seropositive and PCR-positive for the S13 chickens. Seroconversion occurred at or near sexual maturity after natural infection in seven flocks studied.