Developments in biologicals最新文献

Bats are important reservoir hosts of RNA viruses, including lyssaviruses, which can cross the species barrier to infect humans and other domestic and wild non-flying mammals. Six of the seven Lyssavirus genotypes described to date infect bats. In Europe, two genotypes of Lyssavirus, European bat Lyssavirus types 1 and 2 (EBLV-1 and EBLV-2), circulate among several bat species and numerous bats are found infected every year. To provide epidemiologists and public health officials with data to effectively implement public health measures, we have undertaken field studies to identify the temporal dynamics of virus infection in bat colonies by combining multidisciplinary approaches. We have focused our work on a long-term longitudinal survey of different bat colonies in the Balearic Islands. The prevalence of virus RNA and neutralizing antibodies were analysed in captured bats. The bats were banded to allow for individual monitoring of infection and movements between colonies. The results show different lyssavirus infection episodes across the twelve years of study and provide the first evidence that mortality of the mouse-eared bat (Myotis myotis) in their natural environment does not increase significantly after episodes of EBLV-1 infection.

Haptoglobin (Hp) is an acute phase protein that is a marker in blood for clinical and subclinical disease in the pig. The aim of this study was to identify single nucleotide polymorphisms (SNPs) in the Hp gene and analyse their influence on baseline serum levels. DNA samples and serum were collected from 345 boars. Of 13 SNPs identified, 5 were genotyped using PCR-RFLP and Pyrosequencing. Serum Hp levels were measured using a biochemical assay. A general linear model was fitted with line and genotype as fixed effects. In addition, linkage disequilibrium (LD) was estimated between the 5 SNPs using r-square and D prime. Serum Hp concentrations in the population showed a skewed distribution with a mean of 0.34 g/L (range 0-2.65 g/L). Three SNPs were found to be associated with baseline Hp levels (p-value = 0.0093, 0.0051 and 0.0094). These 3 SNPs were also found to be in high LD with each other. This is the first study to find associations between polymorphisms in the porcine Hp gene and baseline Hp serum levels. The results have implications for breeding for resistance to infection.

In Thailand, the animal most reported rabid is the stray dog. Dog bite related rabies cases in humans account for 70-95% of rabies related deaths. The reported incidence of dog bites is highest in the central part of the country, especially in Bangkok. This epidemiological survey shows that at least five different canine rabies virus types are present in Bangkok. Rabies antigen and antibody prevalence in stray dogs in Bangkok was also investigated. Saliva and serum samples were taken from 3,314 stray dogs, captured between December 2003 and June 2004. One two year-old female was antigen positive by latex agglutination test and the result was confirmed by reverse transcription-polymerase chain reaction (RT-PCR). The overall antibody seroprevalence by enzyme-linked immunosorbent assay was 62% (95% CI: 54, 70%). Antibody seroprevalence was higherfor dogs captured within central Bangkok (86% of 1,208 dogs captured) than in the dogs captured on the outskirts of the greater metropolitan area (49% of 2,106 dogs captured). If our sample of stray dogs is representative, then the seroprevalence achieved from previous vaccination campaigns is insufficient in order to break the rabies transmission cycle among stray and feral dogs.

The United Kingdom has performed passive surveillance for European bat lyssaviruses (EBLVs) since 1987, and species-targeted surveillance since 2003. One critical component of these studies is the accurate identification of bats either submitted for testing or sampled in the field. Identification is dependent on numerous morphological characteristics. Whilst this is an effective means of bat identification, a number of problems remain with this approach. It relies on the experience of bat specialists and can lead to problems in differentiating members of the Myotis genus, particularly between Myotis mystacinus (whiskered bat) and Myotis brandtii (Brandt's bat), and between the most common species of the genus Pipistrellus. Furthermore, degradation of bats submitted for testing can also lead to problems in making an accurate species identification. Comparison of genetic sequence data could offer an alternative approach to differentiating bat species when morphological characterisation is not possible. Using tissue samples from UK resident bat species, sequence analysis of the mitochondrial DNA cytochrome b gene, and the beta-actin gene allowed for identification of many of the most common bat species in the UK, and genetic separation of two morphologically cryptic species. Application of this approach identified the species of a bat infected with EBLV-2 in Surrey as Myotis daubentoni (Daubenton's bat).

Porcine reproductive and respiratory syndrome virus (PRRSV), an arterivirus, is the etiologic agent of an infectious disease of that name, characterized by respiratory disorders, abortion in pregnant sows and high mortality in piglets, resulting in significant economic losses in the pig industry worldwide. In order to identify whether genetic differences in PRRSV response may exist in pigs, alveolar macrophages were used to assess the progression of the type-I interferon (IFN) transcript response in porcine alveolar macrophages infected by PRRSV. Our results suggest that a dynamic differential regulation of the type-I IFN and chemokine transcripts may operate during the first hours of infection with and entry of the virus in alveolar macrophages, and provide a compelling mechanism for the establishment of PRRSV replication in susceptible cells.

Infectious pancreatic necrosis (IPN) is a viral disease currently presenting a major problem to the aquaculture of Atlantic salmon (Salmon salar), during both the freshwater and seawater stages of production. Genetic variation in resistance to IPN has previously been demonstrated and the purpose of this study was to determine whether this variation includes loci of major effect. The initial QTL detection methodology utilized the limited recombination seen in male salmon to detect QTL in ten large full-sib families, using a genome-wide scan of two to three markers per linkage group. QTL were then positioned by adding additional markers to the significant linkage groups in a female-based analysis. The most significant QTL was mapped to LG 21, and further confirmation of the LG 21 QTL is provided in an analysis of the QTL flanking markers in an additional nine full-sib families from the same population. The size of QTL effect is such that the QTL flanking markers can be immediately applied in marker-assisted selection programmes to improve the resistance of salmon populations to IPN, thus reducing mortality due to the disease.

This study evaluated rabies epidemiology in Far EastAsia. Questionnaires were sent by the OIE to Far East Asian countries and eight questionnaires were returned. Data were collected from these returns, as well as from recent publications, to gather information regarding rabies epidemiology in these countries. More than 29,000 human deaths were reported in 2006 in Far East Asia, representing more than 50% of all human rabies cases around the globe. There are only a few countries or regions from which no human rabies was reported in 2006 such as Japan, Singapore, South Korea, Malaysia, Hong Kong, and Taiwan. In many of these rabies endemic countries, the number of human rabies cases has not changed much during the past decade. The only country with a steady decline is Thailand, where the number of cases has decreased from around 200 to about 20 cases per year. The most dramatic changes were observed in China. Human rabies cases declined from around 5,000 cases per year in the 1980s to about 160 in the mid-1990s. However, these trends have since been reversed. A steady increase has been reported over the past 10 years with more than 3,200 cases reported in 2006. Although there are many factors that contribute to the epidemic or endemic nature of rabies in these countries, the single most important factor is the failure to immunize domestic dogs, which transmit rabies to humans. Dog vaccination is at or below 5% in many of these countries, and cannot stop the transmission of rabies from dogs to dogs, thus to humans. It is thus most importantforthese countries to initiate mass vaccination campaigns in dog populations in order to stop the occurrence of human rabies in Far East Asia.

A five year study (1995-1999) was conducted in Northern India to investigate epidemiological aspects of rabies in domestic animals. For this purpose, brain tissue samples were collected from rabies suspect animals including 231 dogs, 79 buffaloes, 46 cattle and 28 wild species. Out of the 384 rabies suspected cases, 56% were positive for rabies by fluorescent antibody test (FAT), the mouse inoculation test (MIT) and histopathological techniques. Variations in clinical signs of rabies were recorded for individual animals with significant differences observed between dogs and bovines with respect to hypersalivation, paralysis, recognition of owners and aggression. Likewise, differences in the clinical course of disease between cows and buffaloes regarding hypersalivation and micturition were observed. Rabies incidence was highest among adult male dogs and indicated a seasonal pattern with more rabies cases during certain months of the year (January to April, and August to November). Its impact on cow/buffalo rabies is discussed. Accumulated history records revealed that 78% of owned rabid dogs were not prophylactically vaccinated against rabies.

Health is one of the most important contributors to animal welfare, productivity and profitability in pig production today. For the past 30 years, pig breeders have focused on genetic improvement of lean growth, feed efficiency, meat quality and reproduction. However, in recent years, selection objectives have been broadened to include livability, robustness and disease resistance. A DNA marker for selection of resistance to F18+ E. coli has been available for several years. This marker decreases mortality and improves growth on farms experiencing post-weaning scours and/or oedema disease. However, for most diseases affecting intensive production systems such as porcine reproductive and respiratory syndrome (PRRS), porcine circovirus type 2-associated diseases (PCVAD), Haemophilus parasuis, and swine influenza virus, resistance is a complex and polygenic trait. Selection for improved resistance to these diseases will be incremental and require use of multiple markers in complex breeding schemes. Novel technologies such as pig gene microarrays, single nucleotide polymorphism (SNP) panels and advanced bioinformatics are being used to identify new health candidate genes for these economically important diseases. Lagging behind, however, is availability of large DNAdatasets from pedigreed populations with accurately measured health phenotypes that are needed to identify associations between SNPs and health traits. Increased focus on datasets with health traits will be the key to finding useable discoveries with new genomics technologies. Currently, the industry uses dozens of SNP markers to increase the accuracy of selection for complex breeding objectives, including disease resistance. As the pig genome is sequenced and barriers to genotyping thousand of markers are eliminated, genomic selection for health traits will receive increasing attention from commercial breeders.