Characterization of Bovine herpesvirus type 4 isolated from cattle with mastitis and subclinical infection by the virus among cattle

An outbreak of contagious mastitis occurred among cattle on a farm, and bovine herpesviruses were isolated from the affected mammary tissues, scabs and abscess discharge of the cattle. A bovine herpesvirus type 4 (BoHV-4)-specific fragment was amplified from the isolates by polymerase chain reaction (PCR). Restriction endonuclease analyses demonstrated that the isolates were related to Movar-like European type BoHV-4. To determine the ratio of BoHV-4 subclinical infection in the cattle, a genomic survey was performed by PCR for cattle that were moved to the animal hygiene service station in Ibaraki prefecture. The BoHV-4 genome was occasionally detected in peripheral blood leukocytes, lymph nodes and nervous tissues. The rate of BoHV-4 subclinical infection was relatively high in the cattle.     

Attempts to immunize cattle against virulent African malignant catarrhal fever virus (alcelaphine herpesvirus-1) with a herpesvirus isolated from American cattle.

Two consecutive weekly inoculations with a herpesvirus isolated from sick cattle in America (707K), protected four out of four steers against a first challenge with virulent African malignant catarrhal fever virus (alcelaphine herpesvirus-1), strain C500. Three of these steers were still protected in a rechallenge carried out 9.5 months after the first challenge. One inoculation with this agent did not protect such steers, and repeated weekly inoculations had the risk of inducing a malignant catarrhal fever-like disease. In addition such repeated inoculation did not necessarily confer adequate protection, either in the first or the second challenge. There was no correlation between the development of virus neutralizing antibody and protection to challenge with the virulent virus. Endonuclease analysis of the genome of 707K virus, revealed differences between the agent and the avirulent cell-free form of the virulent African malignant catarrhal fever virus (WC11).     

Characterisation of a type 2 bovine viral diarrhoea virus isolated from cattle in the UK

Two genotypes of bovine viral diarrhoea virus (BVDV) are recognised. Type 2 was first recognised when virulent strains caused significant losses among cattle in North America. Subsequently, BVDV type 2 has been found in many other countries, but recent studies have shown that only type 1 BVDV is circulating in the UK herds (sheep and cattle) with type 1a predominating. During routine genotyping of UK BVDV isolates, a type 2 isolate was identified. Phylogenetic analysis of the 5'-untranslated region of the viral genome showed it to be a BVDV type 2a, most similar to a low virulent US strain of BVDV type 2. Antigenic typing with a panel of monoclonal antibodies verified this classification. This is the first confirmed isolation of BVDV type 2 found circulating in the UK.     

Mycobacteria isolated from nasal secretions of tuberculin test reactor cattle.

Nasal secretions of 103 Holstein cows from a tuberculosis-infected herd in Argentina were bacteriologically cultured for mycobacteria. Mycobacterium bovis was isolated in 8.7% of the cultures. This method was useful for the detection of active tuberculosis with open lesions. Other mycobacteria, most of which grew rapidly on culture media, were isolated in 32% of the cultures and were of little importance as sensitizing agents to mammalian tuberculin in experimental studies in guinea pigs.     

Virulence markers in Shiga toxin-producing Escherichia coli isolated from cattle.

This study identified potential virulence markers in 93 eae-positive and 179 eae-negative Shiga toxin-producing Escherichia coli (STEC), isolated from a random sampling of healthy cattle in southwestern Ontario. PCR amplification was used to identify genes for enterohemorrhagic E. coli (EHEC)-hemolysin, the EAF plasmid, and bundle-forming pili (Bfp); adherence to HEp-2 cells and to bovine colonocytes, and the fluorescent actin staining (FAS) test were used to characterize interaction of the bacteria with epithelial cells. The EHEC-hemolysin sequences were detected in 98% of eae-positive isolates compared with 34% of eae-negative isolates. All isolates were negative for EAF and bfp sequences. There was 100% correlation between localized adherence (LA) to HEp-2 cells and the FAS test. Forty-eight (52%) of the eae-positive isolates were LA/FAS-positive, whereas none of the 179 eae-negative isolates was positive in either test. Among the eae-negative isolates, 20 (11%) showed diffuse adherence and 5 (2.8%) showed enteroaggregative adherence to HEp-2 cells. Seventy-three percent of the eae-positive isolates adhered to bovine colonocytes, whereas only 26% of 120 eae-negative isolates that were tested adhered. All 13 O157:H7 isolates were positive for eae and EHEC-hemolysin gene sequences, LA/FAS, and adherence to bovine colonocytes. It is concluded that possession of genes for eae and EHEC hemolysin is correlated with the serotype of STEC, that production of EHEC hemolysin was highly correlated with serotypes implicated in human disease, and that none of the potential markers that were examined can be used to predict the potential virulence of an isolate.     

Malignant catarrhal fever. I. Response of American cattle to malignant catarrhal virus isolated in Kenya.

Fifty-three American cattle were inoculated with malignant catarrhal fever virus isolated from a wildebeest in Kenya. Three animals showed the mild form of the disease and recovered, and 47 showed the severe form of the disease. The other three did not react. Of the 47 cattle, 28 died, 16 were killed for the collection of specimens and three recovered. The incubation period for the 47 cattle ranged from 16 to 29 days and the course of the fatal disease for 28 cattle averaged three to 23 days. Virus titration of specimens from nine infected steers yielded a mean titer of 10(4)/TCID50 per gm for lymph nodes, 10(3) TCID50 per mL for buffy coats and 10(2.3) TCID50 per gm for spleens. Smaller amounts of virus were found in the liver, kidneys, adrenals and thyroids. Malignant catarrhal fever virus was also found in nasal secretions and saliva of viremic cattle. Viral infectivity was shown in bovine buffy coat cells stored at 4 degrees C for two days but was immediately destroyed upon freezing even when glycerine or dimethylsulfoxide was added. Viral particles were not found in infected animal tissues by electron microscopy. The disease was successfully transmitted in steers by intratracheal intubation and by aerosol inhalation but not by contact.     

Susceptibility of Sudanese sheep to a bluetongue virus isolated from apparently healthy cattle in the Sudan

This study intends to clarify the role of apparently healthy cattle as a reservoir of bluetongue (BT) virus to sheep in the Sudan. It confirms earlier work and establishes that cattle can harbour bluetongue virus to which sheep are susceptible in the country. Experimental transmission of BT virus between the two species suggests that the best indicator to determine viraemia in apparently healthy cattle is to inoculate susceptible sheep with suspected cattle virus. The condition of the viraemia and the virus survival in the field are discussed.     

Enterotoxigenic Clostridium perfringens type A isolated from intestinal contents of cattle, sheep and chickens.

One hundred and fourteen strains of Clostridium perfringens, isolated from the intestinal contents of cattle, sheep, and chickens with enteritis or other disease conditions were studied for their ability to produce enterotoxin. Reversed passive hemagglutination, fluorescent antibody and immunodiffusion tests were used. On the basis of the reversed passive hemagglutination titres, supported by the other two tests, enterotoxigenicity of the strains was arbitrarily classified into two categories: highly enterotoxigenic and potentially enterotoxigenic, with 12% falling into each category. All the highly enterotoxigenic strains originated from cases of enteritis and included all three animal species. Apart from enterotoxigenicity, one C. perfringens strain produced beta toxin (type C) and 21 strains produced large amounts of alpha-toxin. The latter strains were predominantly associated with necrotic enteritis in chickens.     

Antimicrobial resistance of thermophilic Campylobacter spp. isolated from cattle in Poland

Campylobacter species are among the most frequently identified bacterial causes of human gastroenteritis. Because Campylobacter spp. harbored by cattle can be transmitted to humans, in this study we investigated antimicrobial resistance of thermophilic Campylobacter isolated from cows. Our study included 150 strains of Campylobacter (143 strains of C. jejuni and 7 strains of C. coli) isolated from cows in South-Western Poland. The minimal inhibitory concentration (MIC) to ciprofloxacin, erythromycin, gentamicin and tetracycline were determined using the agar dilution methodology. All strains of C. coli were susceptible to all four drugs studied. The most frequently detected resistance of C. jejuni was to ciprofloxacin (26 strains 18.2%). Resistance to tetracycline was observed in 5 strains (3.5%). All strains of C. jejuni were susceptible to erythromycin and gentamicin.     

Attempts to characterize bovine viral diarrhea virus isolated from cattle after immunization with a contaminated vaccine

Bovine viral diarrhea virus (BVDV) was isolated from 28 animals with a history of immunization against respiratory disease with a vaccine contaminated with BVDV. The vaccine-derived parental virus strain and the 28 isolates were analyzed using 10 monoclonal antibodies (MAbs) directed against different epitopes and antigenic domains on the major envelope glycoprotein of BVDV. None of the isolates displayed a reaction pattern identical with the parental virus. Instead, seven different reaction patterns (#A-G) emerged. Circumstantial evidence indicated that six of these were vaccine related whereas in one case (pattern #F) the origin of the isolate was unclear. The results indicated that BVDV rapidly changed during animal passages and that the tracing of the vaccine contaminant using Mabs was impossible.     

Genetic and antigenic characterization of bovine viral diarrhoea virus type 2 isolated from cattle in India

Previous studies have shown that bovine viral diarrhoea virus type 1 (BVDV-1) subtype b is predominantly circulating in Indian cattle. During testing for exotic pestiviruses between 2007 and 2010, BVDV-2 was identified by real time RT-PCR in two of 1446 cattle blood samples originating from thirteen states of India. The genetic analysis of the isolated virus in 5′ UTR, N^pro, entire structural genes (C, E^rns, E1 and E2), nonstructural genes NS2-3 besides 3′ UTR demonstrated that the nucleotide and amino acid sequences showed highest similarity with BVDV-2. The entire 5′ and 3′ UTR consisted of 387 and 204 nucleotides, respectively, and an eight nucleotide repeat motif was found twice within the variable part of 3′ UTR that may be considered as a characteristic of BVDV-2. The phylogenetic analysis revealed that the cattle isolate and earlier reported goat BVDV-2 isolate fall into separate clades within BVDV-2a subtype. Antigenic typing with monoclonal antibodies verified the cattle isolate also as BVDV-2. In addition, cross-neutralization tests using antisera raised against Indian BVDV strains circulating in ruminants (cattle, sheep, goat and yak) displayed significant antigenic differences only between BVDV-1 and BVDV-2 strains. This is the first identification of BVDV-2 in Indian cattle that may have important implications for immunization strategies and molecular epidemiology of BVD.