细化搜索
结果 11-20 的 135
Studies on the incidence and control of haemoglobinuria in buffaloes and cattle.
1988
Raz M.A. | Rauf A.M. | Shah M.A. | Ahmad I. | Qureshi M.A.
Detection of white sturgeon iridovirus (WSIV) in wild sturgeons (Actinopterygii: Acipenseriformes: Acipenseridae) in Poland
2020
Hofsoe-Oppermann, Paulina | Kiełpińska, Jolanta | Panicz, Remigiusz | Bergmann, Sven M.
White sturgeon iridovirus (WSIV) disease is caused by a virus of the eponymous family and is mostly triggered by stressful environmental conditions, i.e. high rearing density, excessive handling, or temporary loss of water. The aim of this study was to develop the most effective diagnostic method for quick and efficient confirmation or exclusion of the presence of WSIV. A total of 42 samples (spleen, gills, intestine, skin, kidney, and brain) were collected from eight sturgeon (Acipenser gueldenstaedtii and A. oxyrinchus) aged ≤5+ farmed or caught between 2010 and 2014 in open waters (Dąbie Lake and Szczecin Lagoon). They were tested for WSIV presence using conventional PCR, qPCR, and in situ hybridisation (ISH). In gross examination, all fish appeared to be healthy. Neither species showed clinical signs typical of WSIV infection. In the majority of cases, fragments of iridoviral DNA were found using molecular methods in the kidneys, and also in the liver, gills, and skin. The detection rate using ISH was 47.37% and most commonly the brain and kidney tissues were positive. The most efficient of the methods used was real-time PCR, with 100% effectiveness in detection of WSIV DNA. The study demonstrates the capabilities for WSIV diagnosis available to sturgeon farmers and water administrators, indicating useful methods of adequate sensitivity as well as organs to sample in order to achieve the highest probability of viral detection.
显示更多 [+] 显示较少 [-]Histamine and other biogenic amines in food
2020
Durak-Dados, Agata | Michalski, Mirosław | Osek, Jacek
The aim of this paper is to give an overview of the presence of biogenic amines, particularly histamine, in various food products, discuss the most important factors influencing their accumulation, and address potential toxicity and safe limits in food. Biogenic amines are natural components of animal and plant raw materials, where they are present at concentrations appearing non-harmful to human health. Their increased content in foods results from the activity of endogenous enzymes or from the microbial decarboxylation of amino acids during controlled or spontaneous fermentation, processing, storage, and distribution. General knowledge of biogenic amines, factors favouring their formation and their safe limits in food are useful in preventing exposure to their toxic effects on the human body. Based on this information, appropriate prophylaxis can be applied, which will consist primarily of maintenance of good hygiene standards of raw materials and products, employment of appropriate processing procedures and upkeep of sanitary food storage conditions.
显示更多 [+] 显示较少 [-]African swine fever virus – persistence in different environmental conditions and the possibility of its indirect transmission
2019
Mazur-Panasiuk, Natalia | Żmudzki, Jacek | Woźniakowski, Grzegorz
Since 2007, African swine fever (ASF) has posed a serious threat to the European swine industry. In Poland, the numbers of reported outbreaks in pigs and affected areas grow every year. In 2018, the disease was noted in Western Europe, in Belgium specifically, where several hundred infected wild boars have been detected so far. In 2018, the virus unexpectedly emerged in pig holdings in eastern China, northern Mongolia, Vietnam, and Cambodia, causing worldwide concern about its further spread. Since there is still no vaccine available, the only approach to control the disease is biosecurity. Identification of potential sources of the virus is extremely important in light of its phenomenal survivability. The review summarises the current knowledge about ASFV survivability and resistance to environmental conditions, and discusses the role of indirect contact in spreading the disease.
显示更多 [+] 显示较少 [-]Roles of African swine fever virus structural proteins in viral infection
2017
Jia, Ning | Ou, Yunwen | Pejsak, Zygmunt | Zhang, Yongguang | Zhang, Jie
African swine fever virus (ASFV) is a large, double-stranded DNA virus and the sole member of the Asfarviridae family. ASFV infects domestic pigs, wild boars, warthogs, and bush pigs, as well as soft ticks (Ornithodoros erraticus), which likely act as a vector. The major target is swine monocyte-macrophage cells. The virus can cause high fever, haemorrhagic lesions, cyanosis, anorexia, and even fatalities in domestic pigs. Currently, there is no vaccine and effective disease control strategies against its spread are culling infected pigs and maintaining high biosecurity standards. African swine fever (ASF) spread to Europe from Africa in the middle of the 20ᵗʰ century, and later also to South America and the Caribbean. Since then, ASF has spread more widely and thus is still a great challenge for swine breeding. The genome of ASFV ranges in length from about 170 to 193 kbp depending on the isolate and contains between 150 and 167 open reading frames (ORFs). The ASFV genome encodes 150 to 200 proteins, around 50 of them structural. The roles of virus structural proteins in viral infection have been described. These proteins, such as pp220, pp62, p72, p54, p30, and CD2v, serve as the major component of virus particles and have roles in attachment, entry, and replication. All studies on ASFV proteins lay a good foundation upon which to clarify the infection mechanism and develop vaccines and diagnosis methods. In this paper, the roles of ASFV structural proteins in viral infection are reviewed.
显示更多 [+] 显示较少 [-]Pathogenicity of FtsK mutant of avian pathogenic Escherichia coli
2016
Xu, Xiaojing | Chen, Xiang | Gao, Song | Zhao, Lixiang
Introduction: Avian pathogenic Escherichia coli (APEC) is a leading cause of extraintestinal infection and heavy economic losses. Imparting immunity after vaccination with live attenuated strain vaccination is an ideal strategy for infection control. This study considers an FtsK knockout mutant strain as a candidate. Material and Methods: An FtsK knockout mutant of APEC strain E058 was constructed and the pathogenicity of the mutant and wild-type strains was further evaluated in chickens. Results: The 50% lethal doses of each strain for one-day-old specific-pathogen-free (SPF) chickens challenged experimentally via trachea were 10⁵.⁵ and 10⁷.⁰ colony-forming units (CFU) respectively. Chickens challenged with the wild-type strain exhibited typical signs and lesions of avian colibacillosis, while those inoculated with the mutant strain showed mild pericarditis and pulmonary congestion. The growth rate of the FtsK mutant strain was much slower than the wild-type strain in the heart, spleen, liver, and lung of infected chickens. Conclusion: These results indicated that the APEC FtsK mutant can be attenuated for chickens, and that this mutant has the potential for the development of an APEC vaccine.
显示更多 [+] 显示较少 [-]Cloning and identification of PK15 cells for enhanced replication of classical swine fever virus
2020
Yin, Mei | Hu, Dongfang | Li, Peng | Kong, Lingyun | Ning, Hongmei | Yue, Feng | Jiang, Jinqing | Wang, Xuannian
Classical swine fever virus (CSFV) causes an economically important and highly contagious disease of pigs, leading to economic losses around the world. Attenuated live vaccines with CSFV antigens have played an important role in the prevention and control of the disease. Porcine kidney 15 (PK15) cells have been widely used for the propagation of CSFV, but this cell line is not efficient or homogeneously susceptible to viral infection. To achieve a homogeneous PK15 cell line which enabled high titre replication of CSFV, we used the limiting dilution cell cloning method. We developed two cell clones, PK15-1A6 and PK15-3B1, which respectively have high- and low-permissive phenotypes to CSFV infection. The PK15-1A6, PK15-3B1, and PK15 parent cells showed different characteristics in cell proliferation rate, susceptibility to CSFV infection, and CSFV production. The mean virus titres per millilitre reflected by TCID₅₀ values in PK15-1A6, PK15-3B1, and PK15 parent cells were 106.85, 103.63, and 104.74, respectively. The PK15-1A6 cell clone is more permissive to CSFV infection than the PK15 parent cells. The screened high-permissive cells will be useful for CSFV propagation and vaccine development in vitro, and facilitate research on the pathogenicity of CSFV.
显示更多 [+] 显示较少 [-]Assessment of pig saliva as a Streptococcus suis reservoir and potential source of infection on farms by use of a novel quantitative polymerase chain reaction assay
2018
Arai, Sakura | Kim, Hyŏn-jŏng | Watanabe, Takayasu | Tohya, Mari | Suzuki, Eriko | Ishida-Kuroki, Kasumi | Maruyama, Fumito | Murase, Kazunori | Nakagawa, Ichiro | Sekizaki, Tsutomu
OBJECTIVE To evaluate colonization of Streptococcus suis and Streptococcus parasuis on pig farms in Japan and to identify sources of infections. SAMPLE Saliva, feces, and vaginal swab samples from 84 healthy pigs of several growth stages on 4 farms and swab samples of feed troughs and water dispensers at those farms. PROCEDURES Samples were collected from August 2015 to June 2016. Two quantitative PCR (qPCR) assays (one for S suis and the other for S parasuis) were designed for use in the study. The novel qPCR assays were used in combination with previously described qPCR assays for S suis serotype 2 or 1/2 and total bacteria. Relative abundance of bacteria in each sample was evaluated. RESULTS Streptococcus suis was detected in all saliva samples and some of the other samples, whereas S parasuis was not detected in any of the samples, including saliva samples, which indicated a difference in colonization preference. The ratio of S suis to total bacteria in saliva appeared to increase with age of pigs. Streptococcus suis serotype 2 or 1/2 was detected in a few saliva samples and feed trough swab samples at 2 farms where S suis infections were prevalent. CONCLUSIONS AND CLINICAL RELEVANCE Saliva, especially that of sows, appeared to be a reservoir and source of S suis infection for pigs. The qPCR assay described here may provide an effective way to monitor for S suis in live pigs, which could lead to effective disease control on pig farms.
显示更多 [+] 显示较少 [-]Efficacy of neem leaf powder for treatment of coccidiosis in young goats
2016
Chandrawathani P. | Priscilla F. X. | Ramlan M. | Ahmad Rasul R. | Premaalatha B. | Julailiyani K. | Jamnah O.
A study was carried out to analyse the efficacy of neem leaf powder, administered in a capsule against coccidiosis in young goats as well as to identify the species of coccidia found in a selected private farm in Sungai Siput, Perak. A total of seven Eimeria spp were found, in faecal samples from the experimental goats, namely; E. arloingi,E. hirci, E. alijevi, E. christenseni, E. jolchijevi, E. ninakohlyakimovae and E. caprina at a rate of 40%, 23%, 14%, 7%, 5% and 2% respectively. Two types of treatment for coccidiosis, herbal and synthetic, were given to 24 young goats for a period of 8 weeks to evaluate the effectiveness of a herbal product, that is the neem leaf powder capsule, a product of the Veterinary Research Institute.Results show that there is no significant differences (p>0.01) between neem capsule treatment and a synthetic drug (sulphurbased) treatment in treating coccidiosis infection. This study shows that neem leaf powder can be an effective substitute for controlling coccidiosis in goats
显示更多 [+] 显示较少 [-]Efficacy of Fostera PRRS modified live virus vaccine against a Canadian heterologous virulent field strain of porcine reproductive and respiratory syndrome virus
2016
Savard, Christian | Alvarez, Fernando | Provost, Chantale | Chorfi, Younes | D'Allaire, Sylvie | Benoit-Biancamano, Maria-Odile | Gagnon, Carl A.
Vaccination is a useful option to control infection with porcine reproductive and respiratory syndrome virus (PRRSV), and several modified live-PRRSV vaccines have been developed. These vaccines have shown some efficacy in reducing the incidence and severity of clinical disease as well as the duration of viremia and virus shedding but have failed to provide sterilizing immunity. The efficacy of modified live-virus (MLV) vaccines is greater against a homologous strain compared with heterologous PRRSV strains. The objective of this study was to evaluate the efficacy of Fostera PRRS MLV vaccine in protecting against challenge with a heterologous field strain widely circulating in the swine herds of eastern Canada. Forty-six piglets were divided into 4 groups: nonvaccinated-nonchallenged; nonvaccinated-challenged; vaccinated-challenged; and vaccinated-nonchallenged. The animals were vaccinated at 23 d of age with Fostera PRRS and challenged 23 d later with a heterologous field strain of PRRSV (FMV12-1425619). Overall, the vaccine showed some beneficial effects in the challenged animals by reducing the severity of clinical signs and the viral load. A significant difference between nonvaccinated and vaccinated animals was detected for some parameters starting 11 to 13 d after challenge, which suggested that the cell-mediated immune response or other delayed responses could be more important than pre-existing PRRSV antibodies in vaccinated animals within the context of protection against heterologous strains.
显示更多 [+] 显示较少 [-]