Modern veterinary vaccines and the Shaman's apprentice

This paper is an overview and assessment of new, commercially available veterinary vaccines placed in a historical context. The authors critically evaluate the current state of the field of veterinary vaccines in both food and companion animals and the promises for future vaccine development. The authors maintain that there is considerable variability in safety and sustained efficacy among veterinary vaccines, especially those developed for companion animals. It is proposed that establishment of an international vaccine advisory committee be supported which would function to apprise the veterinary profession of the current status of vaccines and their use.     

Aspects of emergency vaccination against foot-and-mouth disease

Emergency vaccination is one of several measures which may be deployed to control outbreaks of foot-and-mouth disease. It can be a valuable adjunct to the application of the essential zoosanitary controls which must include rapid diagnosis, tracing, movement control and disinfection and which may also include slaughter of infected and in-contact animals and their safe disposal. Criteria which determine the successful application of emergency vaccination include access to vaccine(s) that (i) contain virus strain(s) of sufficient antigenic relatedness to the outbreak strain(s) (ii) are of the required type of vaccine formulation (iii) have acceptable innocuity and potency (iv) have appropriate availability, including quantity and immediacy of supply and (v) meet considerations of cost. Contingency planning should include provision for emergency vaccination and must address the complex decisions of not only when, where, and how to apply vaccine but also its economic consequences. Computer modelling may be a useful aid to cost benefit and decision support systems in this context. Planning must be detailed and regularly reviewed and should ensure, (i) that the legal and financial aspects are catered for (ii) that any contractual supply agreements are in place (iii) that information is collected and its currency maintained on the species, numbers and whereabouts of susceptible livestock (iv) that vaccination teams are formed and trained (v) that the vaccine cold chain is established and maintained (vi) that supplies of vaccination equipment are held in readiness and (vii) that briefing materials are available to inform the various stakeholders on relevant aspects of emergency vaccination. Knowledge concerning the characteristics and performance of emergency vaccines is summarised and areas identified for further research.     

Persistent detection of peste de petits ruminants antigen in the faeces of recovered goats

Peste des petits ruminants (PPR) disease was confirmed in West African Dwarf goats. They were managed symptomatically with antibiotics and antidarrhoeics. Following clinical recovery, faeces were collected every week from 40 recovered goats to monitor excretion of the PPR virus haemagglutinins in their faeces. All the 40 recovered goats shed the PPR virus haemagglutinins for 11 weeks post recovery. Nine goats (22.5%) continued shedding the viral antigen 12 weeks post recovery. There was correlation between weekly mean haemagglutination titre of the PPR virus and time post recovery with r = -0.7504 (p < 0.01).     

Towards a dengue vaccine: progress to date and remaining challenges

The increased incidence and extended geographical reach of Dengue virus over the past two decades have made the development of an effective vaccine an international urgency. Various strategies are being pursued, including live, vectored and killed/recombinant preparations. For all approaches, the challenge is to induce a broad durable immune response against all four serotypes of Dengue virus simultaneously whilst avoiding the possible exacerbation of risk of developing the severe forms of disease through incomplete or modified responses. This review presents the current state of knowledge and discusses the challenges of further clinical development.     

Pathogenic 'Bison-type' Mycobacterium avium subspecies paratuberculosis genotype characterized from riverine buffalo (Bubalus bubalis) in North India

Despite low per-animal productivity of ruminants in developing countries, Johne's disease has not been investigated in buffaloes, which are primarily found in these countries. This is due to lack of expertise, diagnostic kits and priority to production diseases like Johne's disease. Presence of pathogenic Mycobacterium avium subspecies paratuberculosis (Map) was investigated by screening of target tissues (mesenteric lymph nodes and large intestine) by culture and IS 900 PCR, in 50 sacrificed buffaloes. Indigenous ELISA kit originally developed for goats and sheep was standardized in buffaloes and used to estimate sero-presence of Map in 167 serum samples representing population of buffaloes in Agra region of North India. In culture, 48.0% buffaloes were positive from 50 tissues each from mesenteric lymph nodes (34.0%) and large intestine (36.0%). IS 900 PCR was standardized using specific primers (150 C and 921) and 229 bp-amplified product was characteristic for Map. Of the 25 mesenteric lymph nodes, 40.0% were positive in IS 900 PCR. Genomic DNA from Map cultures was successfully amplified from all the 24 isolates (100.0%). Map was further genotyped as 'Bison type' using IS 1311 PCR-REA. Culture of tissues showed high presence of Map in target tissues, despite high culling rate in buffalos in view of high demand of buffalo meat. Specific tissue-PCR provided rapid confirmation of Map infection in sacrificed buffaloes. In tissue-PCR, all the cultures were positive as compared to 40.0% detected directly from tissues. ELISA kit using indigenous protoplasmic antigen was highly sensitive as compared to commercial antigen in detecting Map infection therefore, could be used as 'Herd Screening Test' in buffaloes against Johne's disease. This pilot study first time reports a highly pathogenic 'Bison-type' genotype of M. avium subspecies paratuberculosis from the riverine buffaloes (Bubalus bubalis) of Agra region in North India.     

Histopathological classification of systemic Mycobacterium avium complex infections in slaughtered domestic pigs

The aim of this study was to classify the histopathological features of pigs infected with Mycobacterium avium complex (MAC). We used slaughtered pig organs systemically infected with MAC. The results showed granulomatous lesions which were observed predominantly in the digestive organs and regional lymph nodes rather than respiratory organs. The histological picture showed a wide range of granulomatous stages from exudative to fibrotic reactions to the MAC infection. Eosinophils and giant cells were characteristically observed in the exudative reactions. The histopathological type in primary focus tended to be maintained in the respective organs. Most strains with the same genotype showed pathogenicity for guinea pigs irrespective of the type of granuloma. Although these findings suggest that different stages of a granulomatous lesion originating from the same causative agent might influence histological patterns, other possibilities such as the hereditary background of the host, or the effects of viral infections should be considered.     

温度对豹纹鳃棘鲈幼鱼呼吸代谢的影响

研究了温度为15、20、25、30、35℃时豹纹鳃棘鲈幼鱼的代谢情况,并分析了幼鱼利用蛋白质、脂肪和糖类作为能源物质的供能情况。试验结果表明,在15~30℃范围内,各试验组耗氧率、排氨率和二氧化碳排出率均随温度的升高而升高,且差异显著(P0.05);在15~30℃范围内,各试验组呼吸熵、氨熵、代谢率和排泄率均随温度的升高而升高,35℃时均下降。根据氧氮比的分析结果可知,豹纹鳃棘鲈幼鱼主要利用脂肪和蛋白质供能,且随着温度的升高,脂肪和碳水化合物供能的比例逐渐增大。Q10的变化规律反映出豹纹鳃棘鲈幼鱼的适温范围为15~30℃,且温度显著影响豹纹鳃棘鲈幼鱼的代谢率。     

不同套种作物对宽叶羌活生长的影响

［目的］研究不同套种作物对宽叶羌活生长的影响,为羌活栽培技术的研究提供科学依据。［方法］分别将羌活与蚕豆套种、羌活与小麦套种、羌活与油菜套种,并观察不同套种田羌活根部性状、叶部性状及生物量性状;测定试验地土壤中各养分含量的变化。［结果］蚕豆、小麦、油菜对套种羌活的基本苗、出叶数、侧根数没有显著影响;蚕豆茬口促进羌活根、叶片、茎的生长及生物量的增加作用明显高于小麦田和油菜田的促进作用;蚕豆、小麦、油菜茬口的全氮、全磷、全钾、有机质和pH值在生长季变化较小,速效养分普遍下降,其中,蚕豆茬下降明显,尤以速效氮下降最明显。［结论］ 小麦茬口有利于促进羌活根的生长,蚕豆茬口有利于促进羌活叶的生长。     

微波消解——石墨炉原子吸收法测定椰果中铬

椰果是以椰子汁(乳)为主要原料，经灭菌、发酵制成的一种纤维素凝胶状物质。采用微波消解法溶解椰果样品，较干灰法节约时间、提高准确度；较压力罐消解法更方便、安全。试验证明，此法消解椰果快速、完全，样液透明，方法准确可靠。微波消解——石墨炉原子吸收法测定椰果中铬是一种比较理想的方法。