Epizootic of anthrax in Falls County, Texas.

An epizootic of anthrax in Eastern Falls County, Texas, killed at least 238 animals during a 6-week period ending July 31, 1974. Infection appeared to be caused by the ingestion of contaminated soil and grass in the drought-stricken central Texas area. The participation of the Texas Department of Agriculture, the Texas National Guard, and other state agencies was of great assistance to the Texas Animal Health Commission in handling the epizootic and panic stricken public. Use of the unencapsulated Sterne strain spore vaccine was credited with preventing many livestock losses in the area. Contaminated city water was detected during the epizootic but human disease did not result.     

炭疽芽孢杆菌PA-LF1融合蛋白的原核表达及其反应原性研究

【目的】构建炭疽芽孢杆菌弱毒株C40-202PA-LF1融合基因表达载体并对其进行原核表达和反应原性检测,为炭疽亚单位疫苗制备、炭疽诊断和疫苗免疫效果检测提供依据。【方法】根据GenBank中登录的炭疽芽孢杆菌PA和LF基因序列设计2对引物,利用PCR方法从炭疽芽孢杆菌弱毒株C40-202中分别扩增出PA和LF1基因片段,经XhoⅠ限制性内切酶消化后,通过黏性末端进行连接,获得PA-LF1融合基因片段,利用SWISS-MODEL分析软件分别对PA、LF1和PA-LF1融合蛋白进行三级结构预测;将融合基因片段克隆至pET32a(＋)质粒中,构建重组质粒pET32a-PA-LF1,并将重组质粒pET32a-PA-LF1转化大肠杆菌BL21(DE3)感受态细胞进行诱导表达,SDS-PAGE分析重组蛋白表达,Western blotting鉴定融合蛋白并分析其反应原性。【结果】从炭疽芽孢杆菌弱毒C40-202株成功扩增出PA、LF1和PA-LF1融合基因;成功构建了炭疽芽孢杆菌PA-LF1融合基因表达质粒pET32a-PA-LF1,融合蛋白三级结构预测可折叠为正确的空间构象;构建的重组质粒经诱导表达、纯化和SDS-PAGE,获得分子质量为96 ku的融合蛋白,以包涵体形式表达;经Western blotting验证,纯化后的重组蛋白与经Ⅱ号炭疽芽孢苗免疫后的绵羊血清发生特异性结合,表明其具有良好的反应原性。【结论】PA-LF1融合蛋白具有良好的反应原性,可为炭疽诊断和疫苗免疫效果检测提供理论依据,同时也可作为一种炭疽亚单位疫苗的候选组分。     

The phenotypic and genotypic characterization of Bacillus anthracis isolates from Iran

To understand epidemiology of Bacillus anthracis in Iran, the morphological, biochemical, and virulence specifications of 32 B. anthracis isolates, collected from human, sheep, cattle, goat, and environmental specimens obtained from throughout Iran were examined by conventional and molecular approaches. B. anthracis isolates were characterized in multiple ways: (1) capsule formation both on bicarbonate agar and in defibrinated horse blood, (2) motility of vegetative forms, (3) hemolysis on 5% sheep blood agar, (4) penicillin G susceptibility, (5) lecithinase production on egg yolk agar, (6) gelatin hydrolysis, (7) ability to develop “string of pearls” on tryptose agar, and (8) capability to develop mucoid colonies in presence of CO₂ were assessed. In addition, biochemical properties such as indole, methyl red, catalase, citrate utilization, and finally nitrate reduction tests were used. All the tested isolates produced identical morphological and biochemical patterns with those of the vaccine strain B. anthracis 34F2 Sterne. In order to assess potential virulence of isolates at genomic level, PCR protocols assaying for the pXO1 and pXO2 loci were employed. The intriguing high level of phenotypic similarity between Iranian isolates of B. anthracis and the 34F2 Sterne strain deserves further studies at genomic level.     

Anthrax vaccine associated deaths in miniature horses

During a widespread anthrax outbreak in Canada, miniature horses were vaccinated using a live spore anthrax vaccine. Several of these horses died from an apparent immune-mediated vasculitis temporally associated with this vaccination. During the course of the outbreak, other miniature horses from different regions with a similar vaccination history, clinical signs, and necropsy findings were found.     

鸡马立克氏病双价疫苗的免疫效力试验

用“814”、B-1/att弱毒疫苗和HVT疫苗匹配组成双价疫苗,进行实验室和田间免疫效力试验。实验室试验表明,由“814”和HVT匹配构成的双价疫苗,免疫效果很好,优于单价疫苗,尤其明显优于HVT单价疫苗。此双价疫苗的田间试验,也取得了令人满意的结果。     

鸡新城疫、传染性支气管炎、禽流感(H9亚型)三联灭活苗(La Sota株+M41株+Re-9株)应用效果研究

鸡新城疫、传染性支气管炎、禽流感(H9亚型)三联灭活苗(La Sota株+M41株+Re-9株)(三联苗(Re-9株))为国内首个采用基因重组H9亚型禽流感疫苗株研制的新支流三联灭活疫苗。为研究疫苗上市后的实际应用效果,使用7日龄AA肉鸡和260日龄产蛋期蛋鸡评价三联苗(Re-9株)有效性。结果显示:肉鸡免疫后14 d即可激发抗体,免疫后21 d,新城疫病毒(NDV)、传染性支气管炎病毒(IBV)、H9亚型禽流感病毒(H9 AIV)的血凝抑制(HI)抗体分别达8.6log2、6.2log2、8.3log2,出栏时仍维持在较高水平;于免疫后14 d抽样进行NDV、H9 AIV攻毒,对照组均100%发病或排毒,免疫鸡均可获得100%保护;在蛋鸡上,免疫三联苗(Re-9株)后28 d,NDV、IBV、H9 AIV的HI抗体效价分别达12.0log2、7.8log2、12.2log2,免疫后6个月仍可以维持在较高水平。结果表明:三联苗(Re-9株)在实际应用中免疫效果较好,本研究将为鸡新城疫、传染性支气管炎、H9亚型禽流感的防控提供有力支撑。     

The ecology of anthrax spores: tough but not invincible.

Bacillus anthracis is the causative agent of anthrax, a serious and often fatal disease of wild and domestic animals. Central to the persistence of anthrax in an area is the ability of B. anthracis to form long-lasting, highly resistant spores. Understanding the ecology of anthrax spores is essential if one hopes to control epidemics. Studies on the ecology of anthrax have found a correlation between the disease and specific soil factors, such as alkaline pH, high moisture, and high organic content. Researchers initially suggested that these factors influenced vegetative anthrax bacilli. However, subsequent research has shown that vegetative cells of B. anthracis have very specific nutrient and physiological requirements and are unlikely to survive outside a host. Review of the properties of spores of B. anthracis and other Bacillus species suggests that the specific soil factors linked to epidemic areas reflect important environmental conditions that aid the anthrax spores in causing epidemics. Specifically, high levels of calcium in the soil may help to maintain spore vitality for prolonged periods, thereby increasing the chance of spores encountering and infecting a new host. Cycles of runoff and evaporation may collect spores dispersed from previous epidemics into storage areas, thereby concentrating them. Uptake of large doses of viable spores from storage areas by susceptible animals, via altered feeding or breeding behavior, may then allow the bacterium to establish infection and cause a new epidemic. Literature search for this review was done by scanning the Life Sciences Collection 1982-1994 using the keywords "anthrax" and "calcium and spore."     

Study on the efficacy and safety of different antigens and oil formulations of infectious coryza vaccines containing an NAD-independent strain of Avibacterium paragallinarum

The present study was designed to assess and compare three different formulations of the new Onderstepoort infectious coryza (IC) quadrivalent vaccine, which contain an NAD-independent strain of Avibacterium paragallinarum (previously known as Haemophilus paragallinarum), and a commercial IC vaccine, not containing an NAD-independent strain, for their safety and ability to protect chickens of varying ages against virulent challenges with four different serovars of A. paragallinarum, including the NAD-independent strain of the C-3 serovar. Four groups of 140 chickens each were vaccinated at the age of 17 weeks and revaccinated at the age of 19 weeks with each of the four vaccine formulations. A similar sized group of non-vaccinated chickens was used as control. Two rounds of challenge were conducted: a group of chicken in each vaccination group was challenged between 31 and 35 weeks of age, while another group was challenged between 51 and 55 weeks of age. The "in-contact" challenge model was used in this experiment. For each vaccination group, the four challenge strains representing four local serovars were used in each challenge round. The efficacy of the vaccines was compared based on overall protection levels obtained and the duration of protection. The safety of the different vaccines was determined by the severity of post-vaccination reactions. The need for the incorporation of the NAD-independent strain in the vaccine was evidenced by the low protection level against NAD-independent challenge recorded in the group of birds vaccinated with the commercial vaccine. The results obtained confirmed not only the variation in virulence of different South African serovars, with serovar C-3 being the most virulent and serovar B having almost no virulence but also the age related increase in susceptibility. The importance of a suitable formulation of the vaccine is discussed.     

Investigation, control and epizootiology of anthrax in a geographically isolated, free-roaming bison population in northern Canada.

In July 1993 anthrax caused significant mortality in an isolated, free-ranging population of bison (Bos bison athabascae) west of Great Slave Lake in the Northwest Territories. There was no previous record of anthrax in this area. An emergency response was undertaken to reduce the scale of environmental contamination and dissemination of anthrax spores and hence to reduce the likelihood of future outbreaks. One-hundred-and-seventy-two bison, 3 moose (Alces alces), and 3 black bear (Ursus americanus) carcasses were found. Visual detection of carcasses was enhanced with the use of an airborne, remote infrared sensing camera mounted externally on a helicopter. Fifty-five percent of the carcasses were located in forested or shrub-covered sites where detection would not have been likely without the thermal imaging equipment. Carcasses were disposed of by incineration and the sites were decontaminated with formaldehyde. Application of formaldehyde to carcasses prevented scavenging. The outbreak occurred after a prolonged period of drying between April and mid-July 1993 which followed several successive years of flooding of bison habitat. The "spore concentration hypothesis" provides the most conservative explanation for the occurrence of anthrax under the observed conditions.     

Increased mortality in mice infected with rabies virus and subsequently vaccinated against rabies

When mice infected 1 or 2 days before by an IM inoculation after high passage of the virus in the species ("challenge virus standard" strain) received an injection of live (Flury) or inactivated virus, their mortality was increased in comparison with unvaccinated controls. In the case of the inactivated virus vaccine, mortality was proportional to the dose of vaccine received. Conversely, when vaccination was carried out in mice recently infected with the same doses of a heterologous strain adapted to foxes, this phenomenon could not be demonstrated. The consequences of these observations on failures of treatment in animals infected with a homologous strain, cases of rabies occurring after vaccination or quality control of vaccines are discussed.     

Comparison of antibody values in sera of pigs vaccinated with a subunit or an attenuated vaccine against classical swine fever

Ten pigs, aged 85 days, were vaccinated with a subunit vaccine containing 32 g of classical swine fever virus glycoprotein E2 (gp E2) (group 1), and a further 10 pigs were vaccinated with a C strain vaccine (10^4±0.15 TCID₅₀/ml), produced by amplification in minipig kidney (MPK) cell culture (group 2). Nine non-vaccinated pigs served as a control group (group 3). Serum samples were collected before (day 0) and at 4, 10, 21 and 28 days after vaccination and were analysed by two commercially available enzyme immunoassays and by a neutralizing peroxidase-linked assay (NPLA). At the same times, peripheral blood was taken for determining the total leukocyte count and the body temperature was taken daily. Antibodies were not detected in serum samples collected before vaccination (day 0), and no side-effects that could be connected with vaccination were observed during the trial. Ten days after vaccination 6/10 pigs vaccinated with the subunit vaccine were seropositive. On days 21 and 28, the ratios of serologically positive to vaccinated pigs were 9/10 and 10/10, respectively. Four of the ten pigs that were vaccinated with the C strain vaccine were positive on day 21 and 9/10 on day 28. However, the results of the NPLA showed that only 4/10 pigs had an antibody titre >1:32 at the end of the trial in both the vaccinated groups, even though the subunit vaccine initiated an earlier and higher level of neutralizing antibodies than the vaccine produced from the C strain. Challenge was performed 28 days after vaccination on four randomly selected pigs from both vaccinated groups. The pigs survived the challenge without showing any clinical signs of classical swine fever (CSF), while two nonvaccinated control pigs died on the 10th and 12th days after infection.     

H9N2亚型禽流感疫苗株的筛选及其免疫效果评价

通过交叉血凝试验,疫苗备用毒株免疫SPF鸡后再用同源和异源毒株攻毒,评价疫苗备用毒株对SPF鸡保护效果。结果显示,H9N2疫苗备用株免疫SPF鸡后,再用H9亚型流感病毒流行株攻毒,SPF鸡咽喉和泄殖腔排毒量大大降低。结果表明,本试验筛选的疫苗备用毒株对H9N2亚型流感病毒具有一定的保护率,完全符合疫苗株要求。     

Antibody response in vaccinated pregnant mares to recent G3BP[12] and G14P[12] equine rotaviruses

Background

Both the G3P[12] and the G14P[12] type of equine group A rotavirus (RVA) have recently become predominant in many countries, including Japan. G3 types are classified further into G3A and G3B. The G3A viruses have been circulating in Europe, Australia, and Argentina, and the G3B viruses have been circulating in Japan. However, only an inactivated vaccine containing a single G3BP[12] strain is commercially available in Japan. To assess the efficacy of the current vaccine against recently circulating equine RVA strains, we examined antibody responses in pregnant mares to recent G3BP[12] and G14P[12] strains by virus neutralization test.

Findings

After vaccination in five pregnant mares, the geometric mean serum titers of virus-neutralizing antibody to recent G3BP[12] strains increased 5.3- to 7.0-fold and were similar to that against homologous vaccine strain. Moreover, antibody titers to recent G14P[12] strains were also increased 3.0- to 3.5-fold.

Conclusions

These results suggest that inoculation of mares with the current vaccine should provide foals with virus-neutralizing antibodies against not only the G3BP[12] but also the G14P[12] RVA strain via the colostrum.     

Use of serology and real time PCR to control an outbreak of bovine brucellosis at a dairy cattle farm in the Nile Delta region,Egypt

Background

Bovine brucellosis remains one of the most prevalent zoonotic infections affecting dairy cattle in developing countries where the applied control programs often fail. We analyzed the epidemiologic pattern of bovine brucellosis in a dairy cattle herd that showed several cases of abortions after regular vaccination with RB51 (B. abortus vaccine). In 2013 thirty dairy cows, from a Holstein-Friesian dairy herd with a population of 600 cattle, aborted five months post vaccination by a regular RB51 vaccine. Blood samples were drawn from milking cows and growing heifers, as well as heifers and cows pregnant up to 6 months. These samples were collected in June 2013 (n?=?257) and May 2014 (n?=?263) and were tested by real time (rt)-PCR as well as serological tests, in particular Rose Bengal Test (RBT), Enzyme-Linked Immunosorbent Assays (ELISA) and Fluorescence Polarization Assay. Tissue specimens were also collected from an aborted fetus and cultured. Isolates were subjected to bacteriological typing tests at the genus and species levels.

Results

Five months post vaccination with RB51 vaccine, Brucella (B.) DNA was detected in blood samples of cows by rt-PCR. The serological tests also revealed the spread of Brucella field strains within the herd in 2013. Four Brucella isolates were recovered from specimens collected from the aborted fetus. These isolates were typed as follows: one B. abortus RB51 vaccine strain and three isolates of B. abortus field strain. The seropositive cows with positive rt-PCR might indicate an infection by the Brucella field strain; while the positive rt-PCR results from seronegative animals may either be due to circulating RB51 vaccine DNA in vaccinated animals or to circulating field strain in infected animals before seroconversion.

Conclusion

The results herein suggest that PCR can be a good supplementary tool in an outbreak situation, if an assay is available that can differentiate vaccine and field strains with a high analytical sensitivity. We recommend using RBT and ELISA in parallel in outbreak situations, to identify as many infected animals as possible during the initial screenings. This test procedure should be repeated for at least three successive negative tests, with one month interval.

     

IBV肾型地方分离株弱毒疫苗与同类冻干疫苗的免疫效力试验比较

本试验对人工致弱IBV肾型地方分离株(SF株)与相应进口弱毒疫苗和国产弱毒疫苗进行了免疫效力比较试验。结果表明SF株免疫后产生抗体的时间和抗体效价高低与其他疫苗相当甚至略高,对攻毒鸡的保护率均为100%。剖检实验鸡,采集肾脏样本做肾脏组织切片,观察发现接种致弱的SF株疫苗后,引起的肾脏组织病理变化比选用的2种国产疫苗病理变化轻微,而与进口疫苗引起的病理变化程度相当,属可逆性病变。     

Molecular identification of the vaccine strain from the inactivated oil emulsion H9N2 low pathogenic avian influenza vaccine

In order to control the H9N2 subtype low pathogenic avian influenza (LPAI), an inactivated vaccine has been used in Korea since 2007. The Korean veterinary authority permitted the use of a single H9N2 LPAI vaccine strain to simplify the evolution of the circulating virus due to the immune pressure caused by the vaccine use. It is therefore important to determine the suitability of the vaccine strain in the final inactivated oil emulsion LPAI vaccine. In this study, we applied molecular rather than biological methods to verify the suitability of the vaccine strain used in commercial vaccines and successfully identified the strain by comparing the nucleotide sequences of the hemagglutinin and neuraminidase genes with that of the permitted Korean LPAI vaccine strain. It is thought that the method used in this study might be successfully applied to other viral genes of the LPAI vaccine strain and perhaps to other veterinary oil emulsion vaccines.     

猪多杀性巴氏杆菌对HeLa细胞附着能力的研究

本研究通过猪肺疫的活菌疫苗和死菌疫苗多杀性巴氏杆菌菌株(Pasteurella multocida,Pm)对小鼠的毒力试验测定它们的毒力性。结果表明,死菌疫苗Pm的毒力性比活菌疫苗Pm的强,即死亡率分别为10 0 %和0 %。通过两菌株对He L a细胞的附着试验测定它们的附着能力,结果证明强毒菌的附着能力明显地比弱毒菌强(P<0 .0 1) ,平均附着数分别为11.96和2 .4 4 ;从上述菌株细胞荚膜中分别提取荚膜蛋白,用SDS- PAGE分离测定两菌株荚膜蛋白质结构,结果表明39k Da荚膜蛋白是强毒菌的特异性蛋白。以上研究结果证明Pm的毒力与He L a细胞的附着能力是密切相关的,同时暗示本菌39k Da荚膜蛋白可能与它们的毒力和He L a细胞的附着能力有关     

Safety of Mycoplasma gallisepticum vaccine strain 6/85 after backpassage in turkeys

The objective of this research was to evaluate the safety of the 6/85 strain vaccine strain of Mycoplasma gallisepticum in turkeys by backpassing the vaccine strain up to 10 times by contact infection in turkeys and challenging turkeys with the resulting backpassaged strain. The vaccine strain, however, did not spread to in-contact turkeys, and it was necessary to reisolate the organism before challenging turkeys for the next passage. The challenge strain, therefore, was one that had been backpassaged four times in turkeys, with a total in vivo time in turkeys of 66 days. The backpassaged 6/85 vaccine strain was no different in pathogenicity than the original vaccine strain, except that at 10 days postchallenge, it was isolated in higher numbers from air sacs. Both the original 6/85 vaccine strain and the backpassaged strain were apathogenic in turkeys, except for a slightly increased diameter of the tracheal mucosa at 10 days postchallenge; at 20 days postchallenge the tracheal mucosal thickness was no different from that of controls.     

Pathology of inhalational anthrax infection in the african green monkey

There is a critical need for an alternative nonhuman primate model for inhalational anthrax infection because of the increasingly limited supply and cost of the current model. This report describes the pathology in 12 African green monkeys (AGMs) that succumbed to inhalational anthrax after exposure to a low dose (presented dose 200-2 x 10(4)colony-forming units [cfu]) or a high dose (presented dose 2 x 10(4)-1 x 10(7) cfu) of Bacillus anthracis (Ames strain) spores. Frequent gross lesions noted in the AGM were hemorrhage and edema in the lung, mediastinum, and mediastinal lymph nodes; pleural and pericardial effusions; meningitis; and gastrointestinal congestion and hemorrhage. Histopathologic findings included necrohemorrhagic lymphadenitis of mediastinal, axillary, inguinal, and mesenteric lymph nodes; mediastinal edema; necrotizing splenitis; meningitis; and congestion, hemorrhage, and edema of the lung, mesentery, mesenteric lymph nodes, gastrointestinal tract, and gonads. Pathologic changes in AGMs were remarkably similar to what has been reported in rhesus macaques and humans that succumbed to inhalational anthrax; thus, AGMs could serve as useful models for inhalation anthrax studies.     

Anthrax outbreak in a Swedish beef cattle herd - 1st case in 27 years: Case report

After 27 years with no detected cases, an outbreak of anthrax occurred in a beef cattle herd in the south of Sweden. The outbreak was unusual as it occurred in winter, in animals not exposed to meat-and-bone meal, in a non-endemic country.The affected herd consisted of 90 animals, including calves and young stock. The animals were kept in a barn on deep straw bedding and fed only roughage. Seven animals died during 10 days, with no typical previous clinical signs except fever. The carcasses were reportedly normal in appearance, particularly as regards rigor mortis, bleeding and coagulation of the blood. Subsequently, three more animals died and anthrax was suspected at necropsy and confirmed by culture and PCR on blood samples.The isolated strain was susceptible to tetracycline, ciprofloxacin and ampicillin. Subtyping by MLVA showed the strain to cluster with isolates in the A lineage of Bacillus anthracis.Environmental samples from the holding were all negative except for two soil samples taken from a spot where infected carcasses had been kept until they were picked up for transport.The most likely source of the infection was concluded to be contaminated roughage, although this could not be substantiated by laboratory analysis. The suspected feed was mixed with soil and dust and originated from fields where flooding occurred the previous year, followed by a dry summer with a very low water level in the river allowing for the harvesting on soil usually not exposed. In the early 1900s, animal carcasses are said to have been dumped in this river during anthrax outbreaks and it is most likely that some anthrax spores could remain in the area.The case indicates that untypical cases in non-endemic areas may be missed to a larger extent than previously thought. Field tests allowing a preliminary risk assessment of animal carcasses would be helpful for increased sensitivity of detection and prevention of further exposure to the causative agent.