Malignant catarrhal fever in pigs and a genetic comparison of porcine and ruminant virus isolates in Finland.

An outbreak of the sheep-associated form of malignant catarrhal fever (MCF) in a Finnish sow herd was diagnosed by histopathology and confirmed by PCR. Several gilts and sows were suffering from high fever and anorexia and had aborted, and six of them had died. Typical signs of lymphoproliferation and vasculitis were observed histologically in several tissues, including the uterus. Ovine herpesvirus-2 (OvHV-2) was detected by PCR in two sows. Sequences of the OvHV-2 tegument protein gene obtained from the sows and from three cases of sheep-associated mcf in Finnish cattle were compared and found to be identical. These are the first confirmed cases of mcf in pigs in Finland.

T-2 toxin-induced DNA damage in mouse livers: the effect of pretreatment with coenzyme Q10 and alpha-tocopherol.

Active oxygen species are reported to cause organ damage. This study was therefore designed to determine whether oxidative stress contributed to the initiation or progression of hepatic DNA damage produced by T-2 toxin. The aim of the study was also to investigate the behaviour of the antioxidants coenzyme Q10 (CoQ10), and alpha-tocopherol (vitamin E) against DNA damage in the livers of mice fed T-2 toxin. Treatment of fasted mice with a single dose of T-2 toxin (1.8 or 2.8 mg/kg body weight) by oral gavage led to 76% hepatic DNA fragmentation. T-2 toxin also decreased hepatic glutathione (GSH) levels markedly. Pretreatment with CoQ10 (6 mg/kg) together with alpha tocopherol (6 mg/kg) decreased DNA damage. The CoQ10 and vitamin E showed some protection against toxic cell death and glutathione depletion caused by T-2 toxin. Oxidative damage caused by T-2 toxin may be one of the underlying mechanisms for T-2 toxin-induced cell injury and DNA damage, which eventually lead to tumourigenesis.

Characterization of biological and antigenic properties of raccoon dog and blue fox parvoviruses: a monoclonal antibody study.

Parvovirus isolates from blue foxes and raccoon dogs were characterized by studying their haemagglutination properties, host range in vitro and antigenic structure. In all 3 characters, raccoon dog parvovirus resembled canine parvovirus (CPV), while blue fox parvovirus was similar to mink enteritis virus (MEV). Monoclonal antibodies (MAbs) were prepared against both viruses. Raccoon dog parvovirus, while resembling CPV, had a unique antigenic site which could be specified by MAbs. The pattern of MAbs prepared against blue fox parvovirus indicated that it is a member of Type 2 MEV.

Significance of apoptosis and its relationship to antioxidants after ochratoxin A administration in mice.

A study of the appearance of liver apoptosis after ochratoxin A (OTA) administration was performed in male mice. Administration of OTA twice a week for one or two weeks period results in the occurrence of apoptosis in mice"s liver. The presence of intracellular apoptosis bodies was detected at two weeks after toxin treatment. Light microscopic examination demonstrated the presence of eosinophilic globules, often containing apoptotic bodies. They were found within the cytoplasm of intact hepatic cells. The number of apoptotic bodies was further enhanced at two weeks, resulting in 8 fold increases in liver over the control values. No evidence of cell necrosis could be observed by histological and biochemical analysis at one week. However, centrilobular necrosis was evident at two weeks. The ability of the combined antioxidants: Coenzyme Q 10 (CoQ 10), L-carnitine, Zn, Mg, N-acetyl cysteine, vitamin C, vitamin E and selenium or tamoxifen to intervene in apoptosis induced in livers of mice by OTA was also investigated. The inhibition by these scavengers was more clear in mice treated with OTA for one week than those mice treated for two weeks. Treatment with tamoxifen, known in restoration of tumor suppressor function and on induction of programmed cell death (apoptosis), after OTA administration, had no significant inhibition effect on the incidence of apoptotic bodies in liver. Because hepatic glutathione represents the major defence against toxic liver injury, we studied the activity of tissue reduced glutathione (GSH), known to inhibit apoptosis. Our finding showed that two weeks after treatment, OTA caused a decrease of the GSH activity. However, treatment of mice with the combined antioxidants could enhance hepatic antioxidant/detoxification system, as indicated by increase in hepatic reduced glutathione level. In the light of these results, apoptosis was observed after two weeks of OTA administration. We also suggest that use of the combined antioxidants may be of interest in conditions were certain toxin-mediated forms of cell death and/or apoptosis contribute significantly to toxicity.

Detection of toxigenic Pasteurella multocida infections in swine herds by assaying antibodies in sow colostrum.

Toxigenic Pasteurella multocida is the causative agent of progressive atrophic rhinitis (PAR), a serious respiratory infection of swine. Diagnosis of the disease has hitherto been based on clinical signs, pathologic findings, and subsequent isolation of the agent. The best Finnish pig breeding herds participating in the Finnish Pig Health Scheme have been surveyed for PAR since 1963, and the disease has been eradicated from these herds. In this study, a total of 5,650 colostrum samples from 188 Finnish Pig Health Scheme herds were analyzed with a new serologic screening method: an enzyme-linked immunosorbent assay (ELISA) able to detect antibodies to the toxin of P. multocida (PMT). Although the herds had been continuously controlled for PAR, 1 herd with PMT antibodies was found. The positive reactions in the ELISA were confirmed by isolating the causative organism. The origin of the infection also appeared to be obvious. The serologic ELISA is a suitable method for the detection and screening of toxigenic P. multocida-infected pig herds.

Comparison of RT-PCR assay and virus isolation in cell cultures for the detection of bovine viral diarrhoea virus (BVDV) in field samples.

The virus isolation-immunoperoxidase test (IPX) on cell cultures and the reverse transcription-polymerase chain reaction (RT-PCR) assay were compared for the detection of bovine viral diarrhoea virus (BVDV) directly in serum samples. Material for this study consisted of 403 sera originating from cattle in 41 BVDV-infected Finnish dairy herds and one suckler cow herd. The presence of virus was demonstrated in 48 samples by both assays. In addition, two more samples were found to be positive by the RT-PCR assay. Both methods proved to be extremely sensitive, detecting pestiviruses even in high serum dilutions, and thus to be suitable for demonstrating the occurrence of persistently infected (PI) cattle. In conclusion, the RT-PCR method used had the advantage of ascertaining BVDV nucleic acid sequences in samples in which the virus had been inactivated, eg during transport or due to the presence of neutralising antibodies.

Pathogenesis of blue fox parvovirus on blue fox kits and pregnant vixens.

To study the pathogenicity of a newly isolated parvovirus of blue fox (Alopex lagopus), pregnant vixens and 43 kits of different ages were experimentally infected with the agent. The kits had no clinical signs of disease, even though most of them excreted virus in their feces, and they responded immunologically to viral exposure. Infection during pregnancy appeared to affect the fetuses. A group of 15 blue fox vixens inoculated with the virus produced a statistically smaller number of kits (78) than did 15 untreated controls (131). Vaccination with a homologous inactivated virus preparation appeared to afford protection against reproductive losses. After infection, 15 vaccinated vixens gave birth to 97 kits, compared with 54 kits born to a similar, non-vaccinated experimental group.

Canine parvovirus infection in housed raccoon dogs and foxes in Finland.

An outbreaks of severe enteritis occurred among young raccoon dogs on fur farms in eastern Finland. Post mortem examinations revealed gross and microscopic lesions which were typical of parvovirus infections described in cats, mink and dogs. The intestine was dilatated, oedematous and the normal villi were significantly reduced. A parvovirus was isolated from faeces and found to resemble canine parvovirus by its ability to haemagglutinate pig erythrocytes at pH 7.2 and its antigenic properties. Experimental inoculations showed that both housed raccoon dogs and foxes are susceptible.

The prevalence of Yersinia enterocolitica 0:3 in Finnish pigs and pork.

One hundred and forty seven samples of pig faeces collected from 14 herds located in different parts of Finland were examined for Yersinia enterocolitica biotype 4 serotype 0:3. Twenty six (17.7%) animals and 5 herds (35.7%) were positive. The tonsils of 350 animals from 35 herds with high condemnation figures at meat inspection and the tonsils of 131 animals from 13 herds with low condemnation figures collected from 2 abattoirs in southwest Finland were also examined. The prevalence raes of Y.e. in animals were 38.3% and 31.3% and in herds 74.3% and 61.5%, respectively. The prevalence of Y.e. in herds with the high and low partial condemnation percentages did not differ significantly. No isolation of Y.e. was made from 104 samples of pork and minced pork collected from retail markets in Helsinki and from exporting slaughterhouses.

Trichinellosis in farmed wild boar: meat inspection findings and seroprevalence.

A reflection of highly prevalent endemic wildlife trichinellosis is seen in wild boar farming in Finland. During the last five years, 0.7% (15/2265) of wild boars undergoing official meat inspection have been determined to be Trichinella-positive. These findings originate from six different farms. In Finland, T. spiralis and T. pseudospiralis have been discovered in meat inspection of wild boars. ELISA showed 11 out of 99 serum samples (11%) as having specific antibodies for T. spiralis crude antigen. Positive samples were from three out of the thirteen farms from which the sera were available. Most of the positive serum samples (8/11) originated from a farm where trichinellosis was also revealed in meat inspection, the other two seropositive farms were without previous Trichinella records. Over the last few decades, no reports have been made of human trichinellosis acquired in Finland. This indicates both efficient meat inspection as well as public awareness of high-risk foodstuff.

Parvovirus antibodies in vaccinated gilts in field conditions--results with HI and ELISA tests.

This study was conducted to determine the antibody response for porcine parvovirus (PPV) of 39 gilts in field conditions after vaccination. Gilts from four herds endemically infected with PPV were injected twice with a commercial vaccine of inactivated PPV and Erysipelothrix rhusiopathiae. The PPV antibodies were analysed both with haemagglutination inhibition (HI) and enzyme-linked immunosorbent assay (ELISA) in order to study the agreement between these methods. The possible association between high-antibody titres and reproductive failure (repeat breeding, culling for infertility, < or = 6 piglets born alive) was also investigated. In these study herds, endemically infected by PPV, most gilts (84.6%) had not seroconverted by the age of 6 months. On-field vaccination resulted in a consistent increase of humoral immunity not exceeding the antibody level of 1 : 512 in the majority of gilts in all herds examined. The agreement between ELISA and HI tests was moderate (Spearman's rho = 0.87, kappa = 0.63). The seroconversion over the level >1:512 by mid-pregnancy was not associated with reproductive failure.

Factors affecting the results of T-2 mycotoxin ELISA assay.

Certain substances in the sample may increase or decrease the reaction between the enzyme and substrate in ELISA assays. During a survey of T-2 trichothecene in food and animal feed 75% of milled grain samples gave a higher O.D. value in competitive T-2 toxin ELISA than the negative control. In samples spiked with small quantities (10 micrograms/kg) of T-2 toxin this type of reaction resulted in underestimates of toxin content. However, the effect was weak and, owing to the high sensitivity of the assay, it did not result in false negative reactions. The low efficiency of the carrier solvent and natural peroxidases in food and feed were considered to be the cause of the inaccurate reactions. A few fermented and processed foodstuffs and feed gave positive results in the T-2 toxin ELISA assay, but verification of the results by gas chromatography (GC) showed that the reactions were false. Certain substances in the samples destroyed or decreased the enzyme activity. False positive reactions can be distinguished from correct ones by retesting the extracts in different dilutions.

Actinobacillus pleuropneumoniae serotype-2 antibodies in sow colostrum in Finnish pig-health-scheme herds.

A direct ELISA with phenol-extracted antigen for Actinobacillus pleuropneumoniae serotype 2 was developed. The test was specific when tested with rabbit antisera prepared against different A. pleuropneumoniae serotypes. It had better-than-moderate repeatability and it made a clear distinction between positive and negative samples. A total of 5477 colostrum samples from breeding sows from herds participating in the Finnish Pig-health Scheme were tested using the ELISA test. A total of 1307 positive samples were found in 129 out of 154 herds, thus indicating that most of the disease-control herds in Finland are infected with A. pleuropneumoniae serotype 2. These infections were almost entirely subclinical.

Antibodies against 12 serotypes of Actinobacillus pleuropneumoniae in finnish slaughter sows.

To determine the prevalence of A. pleuropneumoniae serotypes in Finnish pig populations, 692 blood samples of sows were randomly collected from Finnish slaughterhouses. These were assayed with a direct ELISA for 12 Actinobacillus pleuropneumoniae serotypes. The specificity of the ELISA was tested using rabbit antisera against these serotypes. Cross-reactions were detected between serotypes 6 and 8 and between serotypes 1, 9 and 11, and serotype 5 antiserum reacted with serotype 6 antigen, but the other serotypes did not cross-react. When assaying the blood samples serotype 3 and 2 antibodies were found in 51% and 26% of samples, respectively. Other serotypes were found only in smaller numbers. Most of the samples, 61%, had antibodies towards some serotype of A. pleuropneumoniae. Antibodies towards serotypes 2 and 3 were found in pigs throughout Finland.

Latex agglutination test for detecting feline panleukopenia virus, canine parvovirus, and parvoviruses of fur animals.

A latex agglutination (LA) test for the detection of parvoviruses of fur animals, cats, and dogs was developed, and its sensitivity and specificity were compared with those of hemagglutination (HA) and the enzyme-linked immunosorbent assay (ELISA). Tissue culture isolation was used to confirm the specificity results. Fecal samples from various sources were tested, including specimens from raccoon dogs and mink which were experimentally infected with parvoviruses by oral exposure. LA compared favorably with the other tests. The ELISA was the most sensitive. When it was considered as a reference test, the corresponding sensitivities for HA and LA were 96 and 91%, respectively. The specificities were 93% for the ELISA, 95% for the HA test, and 92% for the LA test. LA seems to be a suitable technique for screening animals in the field and in laboratories in which sophisticated techniques are not available.

Evolution of the feline-subgroup parvoviruses and the control of canine host range in vivo.

A related group of parvoviruses infects members of many different carnivore families. Some of those viruses differ in host range or antigenic properties, but the true relationships are poorly understood. We examined 24 VP1/VP2 and 8 NS1 gene sequences from various parvovirus isolates to determine the phylogenetic relationships between viruses isolated from cats, dogs, Asiatic raccoon dogs, mink, raccoons, and foxes. There were about 1.3% pairwise sequence differences between the VP1/VP2 genes of viruses collected up to four decades apart. Viruses from cats, mink, foxes, and raccoons were not distinguished from each other phylogenetically, but the canine or Asiatic raccoon dog isolates formed a distinct clade. Characteristic antigenic, tissue culture host range, and other properties of the canine isolates have previously been shown to be determined by differences in the VP1/VP2 gene, and we show here that there are at least 10 nucleotide sequence differences which distinguish all canine isolates from any other virus. The VP1/VP2 gene sequences grouped roughly according to the time of virus isolation, and there were similar rates of sequence divergence among the canine isolates and those from the other species. A smaller number of differences were present in the NS1 gene sequences, but a similar phylogeny was revealed. Inoculation of mutants of a feline virus isolate into dogs showed that three or four CPV-specific differences in the VP1/VP2 gene controlled the in vivo canine host range.