Business Link, Strong Ties, and the Walls of Silence: Small and Medium-Sized Enterprises and External Business-Service Expertise

The operation both of private and of public sector organisations consists of a complex interplay between in-house and external expertise and knowledge. The authors use a unique survey of small and medium-sized enterprises (SMEs) in England to explore their use of external expertise and the location of external advisers. They also draw upon surveys both of private sector consultants and of personal business advisers (PBAs) employed by Business Link companies. Network analysis is used to identify the ways in which weak and strong ties either enable or constrain opportunities for SMEs to access the knowledge and expertise available both from private sector business-service companies and from state agencies. SME owner-managers have too many strong ties with their local business community. The paucity of weak tics with individuals located elsewhere in the United Kingdom restricts the ability of SMEs to search for business-service expertise outside their local area. An analysis of the Business Link initiative is undertaken which suggests that the spatial monopoly held by each Business Link company does not encourage them to participate in the development of a national knowledge-and-enterprise network. The analysis suggests that a dual information economy may be developing in the United Kingdom in which large firms arc able to access specialist external expertise irrespective of location, whereas SMEs are tied into local providers of more generalist expertise.

Epizootic haemorrhagic disease

Summary Epizootic haemorrhagic disease (EHD) is an arthropod-transmitted viral disease of certain wild ungulates, notably North American white-tailed deer and, more rarely, cattle. The disease in white-tailed deer results from vascular injury analogous to that caused by bluetongue virus (BTV), to which EHD virus (EHDV) is closely related. There are seven serotypes of EHDV recognised, and Ibaraki virus, which is the cause of sporadic disease outbreaks in cattle in Asia, is included in EHDV serotype 2. The global distribution and epidemiology of BTV and EHDV infections are also similar, as both viruses occur throughout temperate and tropical regions of the world where they are transmitted by biting Culicoides midges and infect a wide variety of domestic and wild ungulates. However, the global distribution and epidemiology of EHDV infection are less well characterised than they are for BTV. Whereas most natural and experimental EHDV infections (other than Ibaraki virus infection) of livestock are subclinical or asymptomatic, outbreaks of EHD have recently been reported among cattle in the Mediterranean Basin, Reunion Island, South Africa, and the United States. Accurate and convenient laboratory tests are increasingly available for the sensitive and specific serological and virological diagnosis of EHDV infection and confirmation of EHD in animals, but commercial vaccines are available only for prevention of Ibaraki disease and not for protection against other strains and serotypes of EHDV.

Bluetongue

Summary Bluetongue (BT) is an arthropod-transmitted viral disease of non-African ungulates, principally sheep. The disease results from vascular injury analogous to that of human haemorrhagic viral fevers, with characteristic tissue infarction, haemorrhage, vascular leakage, oedema, and hypovolaemic shock. Importantly, BT is not zoonotic. Bluetongue virus (BTV) infection of ruminants and vector Culicoides midges is endemic throughout many tropical and temperate regions of the world; however, within this global range the virus exists within relatively discrete ecosystems (syn. episystems) where specific constellations of BTV serotypes are spread by different species of biting Culicoides midges. Recently discovered goat-associated BTVs, notably BTV serotype 25 (BTV-25) in central Europe, appear to have distinctive biological properties and an epidemiology that is not reliant on Culicoides midges as vectors for virus transmission. Bluetongue virus infection of ruminants is often subclinical, but outbreaks of severe disease occur regularly at the upper and lower limits of the virus's global range, where infection is distinctly seasonal. There have been recent regional alterations in the global distribution of BTV infection, particularly in Europe. It is proposed that climate change is responsible for these events through its impact on vector midges. However, the role of anthropogenic factors in mediating emergence of BTV into new areas remains poorly defined; for example, it is not clear to what extent anthropogenic factors were responsible for the recent translocation to northern and eastern Europe of live attenuated vaccine viruses and an especially virulent strain of BTV-8 with distinctive properties. Without thorough characterisation of all environmental and anthropogenic drivers of the recent emergence of BT in northern Europe and elsewhere, it is difficult to predict what the future holds in terms of global emergence of BTV infection. Accurate and convenient laboratory tests are available for the sensitive and specific serological and virological diagnosis of BTV infection and confirmation of BT in animals. Prevention and control strategies for BT are largely reactive in nature, and typically are reliant on vaccination of susceptible livestock and restrictions on animal trade and movement.

Infection trials in pigs with a human isolate of Brucella ( isolate 02/611 'marine mammal type' )

AIM

To determine if pigs could support infection of a human Brucella isolate (Brucella 02/611) from New Zealand, and to study seroconversion to this isolate using a competitive ELISA.

METHODS

Ten weaner piglets were challenged with 4.8 x 10(8) cfu of organisms by the oral and ocular routes. Culture was attempted on blood samples taken prior to challenge, and 4, 7, 9, 11, 14, 21 and 28 days post-challenge, and on tissue samples taken at the termination of the trial, 1 month after challenge. Sera were analysed for antibody using an ELISA. For reference comparison, similar trials were conducted in two pigs using an isolate of Brucella suis biovar 1, and two pigs using an isolate of B. suis biovar 3.

RESULTS

Brucella 02/611 organisms were re-isolated from one lymph node each from three pigs; all other samples were negative. Low and transient antibody titres were detected using a competitive ELISA in three pigs, two of which were culture negative. Organisms of B. suis reference strains were re-isolated from multiple samples from each of the four animals.

CONCLUSION

Brucella 02/611 does not seem to replicate readily in pigs. It is unlikely that pigs were the original maintenance hosts for Brucella 02/611.

Infection and disease in reservoir and spillover hosts: determinants of pathogen emergence

Infection and disease in reservoir and spillover hosts determine patterns of infectious agent availability and opportunities for infection, which then govern the process of transmission between susceptible species. In this chapter, using the zoonotic agents Hendra virus and Nipah virus as examples, the pathogenesis of infection in various species including the wildlife reservoirs and domestic spillover hosts is reviewed with an emphasis on the aspects of pathogenesis which contribute to the dissemination of infection. Through these discussions, the emergence of these zoonotic agents is explored.

Cultured skin fibroblast cells derived from bluetongue virus-inoculated sheep and field-infected cattle are not a source of late and protracted recoverable virus

A recent hypothesis to explain the recurrence of bluetongue disease after winter seasonal absences of the vector has suggested a role for persistent infection of sheep. This report presents combined independent work from two laboratories investigating the possible recovery of Bluetongue virus (BTV) over a protracted period after infection of both sheep and cattle. Prior to infection with either cell-culture-adapted or non-culture-adapted BTV, sheep were subjected to a preliminary exposure to Culicoides sp. insects, which reportedly facilitates recovery of virus from infected sheep several months post-infection (p.i.). A series of skin biopsies at different intervals p.i. was used to establish skin fibroblast (SF) cultures from which attempts were made to detect virus by isolation and by molecular and immunological methods. Also examined was the effect on virus recovery of additional exposure to Culicoides sp. prior to skin biopsy during the post-inoculation period. A herd of cattle sentinels for surveillance of natural BTV infection in northern Australia was monitored prospectively for seroconversion. Evidence of infection initiated attempted virus recovery by establishing SF cultures. It was found that in both cattle and sheep there was not a protracted period over which BTV could be recovered from SF cultures. The data do not support a general hypothesis that BTV persists in either sheep or cattle.

Japanese encephalitis in a racing thoroughbred gelding in Hong Kong

A horse in Hong Kong that had been vaccinated against Japanese encephalitis suffered a pyrexic episode that culminated in a hyperexcitable state and self-inflicted trauma. Japanese encephalitis was diagnosed on the basis of clinical, pathological and serological observations, and confirmed by the detection of genomic sequences of the virus in spinal cord tissue. Phylogenetic analyses of E gene and NS5-3'UTR sequences revealed divergent clustering of these segments with previously described genotypes, suggesting the possibility that the horse might have been infected with a recombinant between genotype I and genotype II viruses. Horses are considered to be dead-end hosts for the disease, but the occurrence of an infected horse in a population may have implications for the health status of the national herd. The effect that this case had on the horse industry in Hong Kong is discussed with specific reference to the movement of horses and the vaccination programme for Japanese encephalitis.

Genetic diversity of bluetongue viruses in Australasia

The authors have characterised the genetic diversity of the bluetongue virus (BTV) RNA segments 3 and 10 from Indonesia, Malaysia and Australia. Analysis of RNA segment 3, which codes for the core protein VP3, showed conserved sequences in the previously defined Australasian topotype, but which further divided into four distinct clades or genotypes. Certain genotypes appeared to be geographically restricted while others were distributed widely throughout South-East Asia. Ongoing surveillance programmes in Australia have identified the movement of Indonesian genotypes into northern Australia and possible reassortment among them. Similarly, analysis of RNA segment 10, which codes for the non-structural protein NS3/3A, showed they were also conserved and grouped into five clades or genotypes, three Asian and two North American/South African.

Genetic diversity of bluetongue viruses in south east Asia

Bluetongue viruses (BTV) were isolated from sentinel cattle in Malaysia and at two sites in Indonesia. We identified eight serotypes some of which appeared to have a wide distribution throughout this region, while others were only isolated in Malaysia or Australia. Nearly half of the 24 known BTV serotypes have now been identified in Asia. Further, we investigated the genetic diversity of their RNA segments 3 and 10. Using partial nucleotide sequences of the RNA segment 3 (540 bp) which codes for the conserved core protein (VP3), the BTV isolates were found to be unique to the previously defined Australasian topotype and could be further subdivided into four distinct clades or genotypes. Certain of these genotypes appeared to be geographically restricted while others were distributed widely throughout the region. Similarly, the complete nucleotide sequences of the RNA segment 10 (822 bp), coding for the non-structural protein (NS3/3A), were also conserved and grouped into the five genotypes; the BTV isolates could be grouped into three Asian genotypes and two Nth American/Sth African genotypes.

Regional overview of bluetongue viruses in South-East Asia: viruses, vectors and surveillance

Structured epidemiological studies based on sentinel herds in Indonesia and Malaysia have provided much information regarding the bluetongue (BT) viruses (BTV) and their likely vectors in South-East Asia. Serotypes 1, 2, 3, 7, 9, 12, 16, 21 and 23 have been isolated. Molecular analyses show all group within the Australasian topotype, with four genotypic sub-groupings identified to date. There are relationships to isolates from both India and Australia. Strains of BTV in South-East Asia do not appear to be highly virulent, since BT disease is not seen in local sheep. Known vector species identified include Culicoides fulvus, C. actoni, C. wadai and C. brevitarsis. C. imicola has not been identified in Malaysian or Indonesian studies. Molecular analyses indicate movement of South-East Asian strains of BTV into northern Australia, and the gradation in observations between India and eastern Australia regarding serotype, genotype, virulence and vector species suggests movement along a conceptual gradient through South-East Asia.

An Outbreak of Highly Pathogenic Avian Influenza in Australia in 1997 Caused by an H7N4 Virus

In November of 1997 an outbreak of highly pathogenic avian influenza occurred near the town of Tamworth, in northern New South Wales, Australia. The viruses isolated from chickens on two commercial chicken farms were identified as H7N4 viruses, with hemagglutinin cleavage site amino acid sequences of RKRKRG and intravenous pathogenicity indices of 2.52 and 2.90, respectively. A virus with an identical nucleotide sequence, but with an intravenous pathogenicity index of 1.30, was also isolated from cloacal swabs collected from asymptomatic emus kept on a third property.

Experimental infections of pigs with Japanese encephalitis virus and closely related Australian flaviviruses

The flavivirus Japanese encephalitis (JE) virus has recently emerged in the Australasian region. To investigate the involvement of infections with related enzootic flaviviruses, namely Murray Valley encephalitis (MVE) virus and Kunjin (KUN) virus, on immunity of pigs to JE virus and to provide a basis for interpretation of serologic data, experimental infections were conducted with combinations of these viruses. Antibody responses to primary and secondary infections were evaluated using panels of monoclonal antibody-based blocking enzyme-linked immunosorbent assays and microtiter serum neutralization tests (mSNTs). Identification of the primary infecting virus was possible only using the mSNTs. Following challenge, unequivocal diagnosis was impossible due to variation in immune responses between animals and broadened and/or anamnestic responses. Viremia for JE virus was readily detected in pigs following primary infection, but was not detected following prior exposure to MVE or KUN viruses. Boosted levels of existing cross-neutralizing antibodies to JE virus suggested a role for this response in suppressing JE viremia.

Serological survey for Ehrlichia canis in urban dogs from the major population centres of northern Australia

OBJECTIVE

To detect evidence of Ehrlichia canis infection of dogs from the major population centres of northern Australia, if present.

DESIGN

Serological investigation for E. canis.

PROCEDURE

The sera of 316 domestic dogs, collected from the northern Australian population centres of Townsville, Cairns, Darwin, Kununurra and Broome from May 1997 to August 1999, were investigated for evidence of infection with E. canis. Samples were tested for antibodies to E. canis using an indirect fluorescent antibody (IFA) test. The buffy coats from blood of dogs whose serum reacted in the IFA test were subsequently tested with a nested PCR to detect E. canis DNA. When available, blood from these dogs was injected into suckling mice, which were then examined for clinical disease and tested for the presence of E. canis antibodies.

RESULTS

Of the 316 samples tested seven reacted in the IFA test for E. canis. None of the dogs from which these samples were obtained exhibited clinical signs of acute or chronic ehrlichiosis. The six positive samples available for testing were negative when tested with the nested PCR. Suckling mice inoculated with blood from three of the dogs whose serum was positive by IFA test showed no signs of clinical disease nor did their give positive reactions in the IFA test.

CONCLUSIONS

No evidence of E. canis infection was confirmed in any of the dogs examined. Northern Australia would appear to remain free of this obligate parasite.

Murray Valley encephalitis virus surveillance and control initiatives in Australia. National Arbovirus Advisory Committee of the Communicable Diseases Network Australia

Mechanisms for monitoring Murray Valley encephalitis (MVE) virus activity include surveillance of human cases, surveillance for activity in sentinel animals, monitoring of mosquito vectors and monitoring of weather conditions. The monitoring of human cases is only one possible trigger for public health action and the additional surveillance systems are used in concert to signal the risk of human disease, often before the appearance of human cases. Mosquito vector surveillance includes mosquito trapping for speciation and enumeration of mosquitoes to monitor population sizes and relative composition. Virus isolation from mosquitoes can also be undertaken. Monitoring of weather conditions and vector surveillance determines whether there is a potential for MVE activity to occur. Virus isolation from trapped mosquitoes is necessary to define whether MVE is actually present, but is difficult to deliver in a timely fashion in some jurisdictions. Monitoring of sentinel animals indicates whether MVE transmission to vertebrates is actually occurring. Meteorological surveillance can assist in the prediction of potential MVE virus activity by signalling conditions that have been associated with outbreaks of Murray Valley encephalitis in humans in the past. Predictive models of MVE virus activity for south-eastern Australia have been developed, but due to the infrequency of outbreaks, are yet to be demonstrated as useful for the forecasting of major outbreaks. Surveillance mechanisms vary across the jurisdictions. Surveillance of human disease occurs in all States and Territories by reporting of cases to health authorities. Sentinel flocks of chickens are maintained in 4 jurisdictions (Western Australia, the Northern Territory, Victoria and New South Wales) with collaborations between Western Australia and the Northern Territory. Mosquito monitoring complements the surveillance of sentinel animals in these jurisdictions. In addition, other mosquito monitoring programs exist in other States (including South Australia and Queensland). Public health control measures may include advice to the general public and mosquito management programs to reduce the numbers of both mosquito larvae and adult vectors. Strategic plans for public health action in the event of MVE virus activity are currently developed or being developed in New South Wales, the Northern Territory, South Australia, Western Australia and Victoria. A southern tri-State agreement exists between health departments of New South Wales, Victoria and South Australia and the Commonwealth Department of Health and Aged Care. All partners have agreed to co-operate and provide assistance in predicting and combatting outbreaks of mosquito-borne disease in south-eastern Australia. The newly formed National Arbovirus Advisory Committee is a working party providing advice to the Communicable Diseases Network Australia on arbovirus surveillance and control. Recommendations for further enhancement of national surveillance for Murray Valley encephalitis are described.

Reproductive disease and congenital malformations caused by Menangle virus in pigs

OBJECTIVE

To describe a new syndrome characterised by embryonic mortalities, stillbirths, mummified foetuses and congenital malformations in a herd of intensively farmed pigs.

DESIGN

Field observations, laboratory investigations and examination of breeding records.

PROCEDURE

Pathology examinations were performed on mummified and congenitally deformed piglets during an outbreak of reproductive disease at a 2600 sow intensive piggery in New South Wales from April to October 1997. Reproductive performance was monitored during the outbreak and breeding records were examined retrospectively. Serum and tissue samples from pigs were tested for evidence of infection with known porcine pathogens and for a new virus, Menangle virus, isolated from stillborn piglets with deformities from the affected piggery in August 1997.

RESULTS

Reproductive disease occurred sequentially in all four breeding units at the affected piggery over a period of 21 weeks. The farrowing percentages in each unit decreased from 80 to 82% before the outbreak to 63 to 78% during the outbreak and the number of live piglets per litter declined from a mean of 9.6 to 9.8 before the outbreak to 7.2 to 8.9 during the outbreak. The proportion of affected litters (litters with less than six liveborn piglets) was highest (64%) in the sixth week of the outbreak. Mummified foetuses, stillborn piglets with arthrogryposis, craniofacial deformities and degeneration of the brain and spinal cord, were observed along with occasional abortions. Sera from sows that produced affected litters contained neutralising antibodies against Menangle virus and there was evidence that this virus had been introduced to the piggery in February 1997.

CONCLUSIONS

Reproductive disease in pigs due to Menangle virus was characterised by stillbirths, mummification, embryonic death and infertility, along with abortions, skeletal deformities and degeneration of the brain and spinal cord in affected foetuses and stillborn piglets.

Emerging viral diseases of Southeast Asia and the Western Pacific

Over the past 6 years, a number of zoonotic and vectorborne viral diseases have emerged in Southeast Asia and the Western Pacific. Vectorborne disease agents discussed in this article include Japanese encephalitis, Barmah Forest, Ross River, and Chikungunya viruses. However, most emerging viruses have been zoonotic, with fruit bats, including flying fox species as the probable wildlife hosts, and these will be discussed as well. The first of these disease agents to emerge was Hendra virus, formerly called equine morbillivirus. This was followed by outbreaks caused by a rabies-related virus, Australian bat lyssavirus, and a virus associated with porcine stillbirths and malformations, Menangle virus. Nipah virus caused an outbreak of fatal pneumonia in pigs and encephalitis in humans in the Malay Peninsula. Most recently, Tioman virus has been isolated from flying foxes, but it has not yet been associated with animal or human disease. Of nonzoonotic viruses, the most important regionally have been enterovirus 71 and HIV.

Japanese encephalitis

Japanese encephalitis (JE) virus is a mosquito-borne flavivirus that can cause encephalitis and death in horses and humans. It is an emerging disease of international concern because it has been spreading into previously nonendemic areas. Major epidemics may occur where the virus moves into new areas, but many infections are subclinical. This article presents information on the virus, its epidemiology, and what little information has been published on the disease in horses. The methods available for the diagnosis and control of JE are described and issues raised, particularly for those countries faced with the threat of imminent incursions as the virus extends its range.

Development of a polymerase chain reaction to detect Vietnamese isolates of duck virus enteritis

A polymerase chain reaction (PCR) method for the detection of duck virus enteritis (DVE) virus in tissues of infected and affected ducks, and in cell culture was developed. This required us to obtain specific nucleotide sequence information as we could not find any specific data about the genome of the virus. We found the assay to be highly effective in detecting the virus under experimental conditions and to be easily transferred to laboratories in Vietnam where it is being used in studies on the epidemiology of the disease. We have applied this simple and rapid diagnostic method to the detection of DVE isolates grown in cell culture and tissues from infected birds. The assay was also able to differentiate DVE from other avian herpesviruses, such as Marek's disease, infectious laryngotracheitis virus and goose herpesvirus.

Transmission studies of Hendra virus (equine morbillivirus) in fruit bats, horses and cats

OBJECTIVE

To determine the infectivity and transmissibility of Hendra virus (HeV).

DESIGN

A disease transmission study using fruit bats, horses and cats.

PROCEDURE

Eight grey-headed fruit bats (Pteropus poliocephalus) were inoculated and housed in contact with three uninfected bats and two uninfected horses. In a second experiment, four horses were inoculated by subcutaneous injection and intranasal inoculation and housed in contact with three uninfected horses and six uninfected cats. In a third experiment, 12 cats were inoculated and housed in contact with three uninfected horses. Two surviving horses were inoculated at the conclusion of the third experiment: the first orally and the second by nasal swabbing. All animals were necropsied and examined by gross and microscopic pathological methods, immunoperoxidase to detect viral antigen in formalin-fixed tissues, virus isolation was attempted on tissues and SNT and ELISA methods were used to detect HeV-specific antibody.

RESULTS

Clinical disease was not observed in the fruit bats, although six of eight inoculated bats developed antibody against HeV, and two of six developed vascular lesions which contained viral antigen. The in-contact bats and horses did not seroconvert. Three of four horses that were inoculated developed acute disease, but in-contact horses and cats were not infected. In the third experiment, one of three in-contact horses contracted disease. At the time of necropsy, high titres of HeV were detected in the kidneys of six acutely infected horses, in the urine of four horses and the mouth of two, but not in the nasal cavities or tracheas.

CONCLUSIONS

Grey-headed fruit bats seroconvert and develop subclinical disease when inoculated with HeV. Horses can be infected by oronasal routes and can excrete HeV in urine and saliva. It is possible to transmit HeV from cats to horses. Transmission from P poliocephalus to horses could not be proven and neither could transmission from horses to horses or horses to cats. Under the experimental conditions of the study the virus is not highly contagious.

An apparently new virus (family Paramyxoviridae) infectious for pigs, humans, and fruit bats

We isolated an apparently new virus in the family Paramyxoviridae from stillborn piglets with deformities at a piggery in New South Wales, Australia. In 1997, the pregnancy rate and litter size at the piggery decreased markedly, while the proportion of mummified fetuses increased. We found serologic evidence of infection in pigs at the affected piggery and two associated piggeries, in humans exposed to infected pigs, and in fruit bats. Menangle virus is proposed as a common name for this agent, should further studies confirm that it is a newly recognized virus.

Australian-Indonesian collaboration in veterinary arbovirology--a review

Australian-Indonesian collaboration in veterinary development programs has led to significant advances in the study of arboviruses. This paper reviews the resulting knowledge of arboviral infections of livestock in Indonesia. The first recognized arboviral disease of animals in Indonesia was bovine ephemeral fever. Serology indicates that the virus is widespread, as are related rhabdoviruses. Local sheep appear resistant to bluetongue disease, but imported sheep have suffered mortalities. Bluetongue viral serotypes 1, 7, 9, 12, 21 and 23 have been isolated from sentinel cattle; 1, 21 and 23 at widely separate locations. Bluetongue serotype 21 has been isolated from Culicoides spp. Serological reactors to Akabane virus are widespread, as are reactors to the flavivirus group. Japanese encephalitis, isolated from sentinel pigs, is the flavivirus of most veterinary importance but the limit of its easterly distribution is unknown. Many of the arboviruses present in Indonesia are also present in Australia and elsewhere in Asia. Their patterns of mobility among countries in the region are largely undescribed, but there are opportunities for further regional collaboration.

Diseases in young farmed crocodiles in Irian Jaya

Thirty-eight young crocodiles that were emaciated and were euthanased or were found dead on 12 farms in Irian Jaya were examined post mortem. Major diseases were coccidiosis (nine crocodiles), pentastomiasis (four), visceral gout (two) and bacterial pneumonia and septicaemia (two). Other diseases and infections were steatitis, fungal pneumonia, gastric capillariasis, haemogregarine infection, ascariasis, filarioid infection and the presence of flukes in the intestine, kidney and blood. Multiple parasitism due to the collection of hatchlings in the wild was considered the primary cause of the ill-thrift and death of the crocodiles.

Isolation of bluetongue virus serotype 21 from Culicoides spp. in Indonesia

The isolation of a bluetongue (BLU) virus from Culicoides spp. in Indonesia is reported. BLU serotype 21 was isolated from a mixed pool of C. fulvus and C. orientalis of the Avaritia subgenus.

Antibodies against certain bluetongue and epizootic haemorrhagic disease viral serotypes in Indonesian ruminants

The orbiviruses contain several important viruses of livestock including bluetongue (BT) and epizootic haemorrhagic disease of deer (EHD) which share some group antigens. Preliminary screening of sera for antibodies to orbiviruses by the agar gel immunodiffusion (AGID) test has previously revealed widespread infections with the BT group in Indonesia. However serum neutralization (SN) tests give a more accurate estimate of exposure to each serotype in the BT and EHD groups, and in this study were applied to sera that had reacted previously in the AGID test. Five different serotypes of BT and one serotype of EHD virus were studied. Reactors to BT serotype 20 were the most prevalent, followed by EHD type 5 and BT types 21, 12, 1 and 17. Antibodies against BT serotype 20 were present in cattle, buffaloes, goats and sheep, but were most common in buffaloes. Buffaloes showed the highest exposure to the BT serotypes tested. Antibody to EHD type 5 occurred most frequently in cattle. Antibodies against all BT and EHD serotypes tested were found in buffaloes and cattle while goats had antibodies against BT types 20, 21 and EHD type 5 and sheep had antibodies only against BT type 20.

Non-effect of regional lymph node removal on growth of ovine aural squamous cell carcinoma

The effect of ipsilateral parotid lymphadenectomy on growth of lesions of aural squamous cell carcinoma in 10 adult ewes was compared over a 6-month period, with matched, tumour-affected controls that were not subjected to parotid lymphadenectomy. There was no significant difference between groups, indicating that the regional lymph node had no influence on the growth of the tumour.

A study of immunoglobulin-containing and other cells in ovine aural squamous cell carcinoma

The peroxidase-antiperoxidase method was used to quantify immunoglobulin (Ig)-containing cells at the host-tumour interface in ovine aural squamous cell carcinoma lesions at various stages of development. IgM-containing cells were never observed; only scattered, but strongly staining, IgA-containing cells were present. IgG-containing cells predominated; their prevalence increased from 0.17 +/- 0.34 cells per high power field (hpf; mean +/- standard deviation) in precursor lesions to a maximum of 13.6 +/- 2.6 cells per hpf in overt tumours which had not metastasized. Their prevalence in overt tumours which had metastasized was 4.6 +/- 3.9 cells per hpf. Quantitation of pyroninophils in sections stained by the methyl green-pyronin method showed a greater prevalence of plasma cells than IgG-containing cells, but a similar pattern of change was apparent. Mast cells were most prevalent in early stages, but no significant change in eosinophil numbers was observed.

Animal model of human disease. Squamous cell carcinoma. Ovine squamous cell carcinoma

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