Humoral immune responses following experimental infection of goats with Mycoplasma capricolum subsp. capripneumoniae.

Goats housed in microbiologically secure facilities were experimentally endobronchially infected with Mycoplasma capricolum subsp. capripneumoniae (Mccp), causal agent of contagious caprine pleuropneumonia (CCPP). The animals were monitored over an 8-week period post-infection (p.i.). Elevated temperatures were observed 2-7 days p.i., reaching a maximum of 41.5 degrees C in one animal (1884). By 8 weeks p.i. the infection was successfully cleared, with no Mccp being recovered from the lungs, serum or nasal passages. Mccp was not isolated from serum throughout the experiment, either directly by culture or indirectly via polymerase chain reaction (PCR). Humoral immune responses against Mccp capsular polysaccharide (CPS) were generally poor when measured by ELISA. CPS antigen was present in the serum of all infected animals early in the infection (day 14 p.i.), although in one animal (1855) CPS antigen persisted throughout. This was the only animal to exhibit a serious cough (day 5-19 p.i.). Successful diagnosis of CCPP was achieved using two different types of latex agglutination test (CPS antibody and CPS antigen detection test), immunoblotting and a blocking ELISA, although the latter lacked sensitivity until later in the infection (35-40 days p.i.). Only a single animal (1855) was detected positive using the current complement fixation test (CFT). Strong immune responses to protein antigens were detected by IgG and IgM immunoblotting from the first time point at day 14 p.i. IgM immunodominant bands of 220, 85, 62 and 40kDa were observed in the 3 infected animals and from CFT-positive CCPP field sera. Band intensity gradually diminished throughout the experiment. IgG immunodominant bands of 108, 70, 62, 44, 40 and 23kDa were shared between experimentally-infected and field sera, with band intensity either remaining unchanged or increasing from day 14 p.i. These bands were not present using pre-infection sera. Of the diagnostic tests used, only the CPS antibody detection latex agglutination test and IgG immunoblotting gave positive diagnoses throughout the entire period post-infection (days 14-53 p.i.).     

Ergovaline does not alter the severity of ryegrass staggers induced by lolitrem B

AIM: To investigate a possible interaction between lolitrem B and ergovaline by comparing the incidence and severity of ryegrass staggers in sheep grazing ryegrass (Lolium perenne) containing lolitrem B or ryegrass containing both lolitrem B and ergovaline.

METHODS: Ninety lambs, aged approximately 6 months, were grazed on plots of perennial ryegrass infected with either AR98 endophyte (containing lolitrem B), standard endophyte (containing lolitrem B and ergovaline) or no endophyte, for up to 42 days from 2 February 2010. Ten lambs were grazed on three replicate plots per cultivar. Herbage samples were collected for alkaloid analysis and lambs were scored for ryegrass staggers (scores from 0–5) weekly during the study. Any animal which was scored ≥4 was removed from the study.

RESULTS: Concentrations of lolitrem B did not differ between AR98 and standard endophyte-infected pastures during the study period (p=0.26), and ergovaline was present only in standard endophyte pastures. Ryegrass staggers was observed in sheep grazing both the AR98 and standard endophyte plots, with median scores increasing in the third week of the study. Prior to the end of the 42-day grazing period, 22 and 17 animals were removed from the standard endophyte and AR98 plots, respectively, because their staggers scores were ≥4. The cumulative probability of lambs having scores ≥4 did not differ between animals grazing the two pasture types (p=0.41).

CONCLUSIONS AND CLINICAL RELEVANCE: There was no evidence for ergovaline increasing the severity of ryegrass staggers induced by lolitrem B. In situations where the severity of ryegrass staggers appears to be greater than that predicted on the basis of concentrations of lolitrem B, the presence of other tremorgenic alkaloids should be investigated.     

Cyclic AMP Signalling During Mammalian Sperm Capacitation – Still Largely Terra Incognita

Cyclic AMP is known to play a major role in intracellular signalling during mammalian sperm capacitation. However, despite much research, many of the molecular details of cyclic AMP's involvement remain obscure. In this review, I discuss the following aspects, presenting some original data as illustration where relevant. With respect to cyclic AMP synthesis, uncertainties exist as to the number of forms of adenylyl cyclase that are present in the spermatozoon, whether they are cytosolic or bound to subcellular structures, and which physiological effectors they respond to (e.g. bicarbonate, Ca²⁺, or receptor‐coupled G‐proteins). While net intracellular levels of cyclic AMP in spermatozoa depend upon the relative activities of adenylyl cyclase and phosphodiesterase, there are wide between‐sample variations within species, both in basal levels and in levels attained after activation of the cyclase (e.g. after sperm treatment with bicarbonate). Moreover, minor changes in bulk cyclic AMP levels can result in large changes in cyclic AMP‐dependent functions. Finally, while cyclic AMP levels respond very rapidly to sperm treatment by effectors such as bicarbonate and Ca²⁺ (key components of capacitating media), there are big discrepancies between the rates of functional response. For example, enhancement of motility and collapse of phospholipid asymmetry take place within a few minutes, whereas more than 1 h of exposure to capacitating conditions is needed for cyclic AMP‐dependent protein tyrosine phosphorylation to become detectable or for the sperm population to attain a capacitated state.     

Studies on helminthosis at the centre for tropical veterinary medicine (CTVM)

Summary The research work relating to helminths, which has been conducted within the Helminthology Section of the CTVM, often in collaboration with colleagues from the tropics is reviewed and placed into a historical perspective. The research has, in the main, concentrated on the trematodesFasciola hepatica andFasciola gigantica and the cestodesTaenia saginata andTaenia solium, but work on other parasites including gastro-intestinal nematodes is also considered. All of these parasites are of obvious veterinary/economic importance particularly in the tropics and subtropics. While the zoonotic importance ofT. saginata andT. solium has been recognised for many years, it is only more recently that the zoonotic impact ofFasciola spp. has been generally acknowledged.

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Estudios Sobre Enfermedades Causadas Por Helmintos En El CTVM

Resumen El artículo revisa y sitúa en una perspectiva histórica la investigación sobre helmintos realizada en la sección de helmintología del CTVM, a menudo en colaboración con otros investigadores de países tropicales. La investigación se ha centrado principalmente en los trematodosFasciola hepatica y Fasciola gigantica y en los cestodosTaenia saginata y Taenia solium, aunque en el artículo se incluye también el trabajo realizado con nematodos gastrointestinales y otros parásitos. Todos los parásitos mencionados tienen una importancia obvia desde el punto de vista veterinario y económico, particularmente en los trópicos y subtrópicos. Mientras que la importancia deT. saginata yT. solium como zoonosis ha sido siempre reconocida, el posible carácter zoonótico deFasciola spp. ha sido descubierto muy recientemente.

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Etudes Sur Les Helminthiases A CTVM

Résumé Le travail de recherche portant sur les helminthes, qui a été mené dans le groupe Helminthologie à CTVM, souvent en collaboration avec des collègues des pays tropicaux, est passé en revue et mis dans une perspective historique. La recherche a principalement porté sur les trematodesFasciola hepatica etFasciola gigantica et sur les cestodesTaenia saginata etTaenia solium, cependant d'autres travaux ont également porté sur d'autres parasites et sur des nématodes gastro-intestinaux.Tous ces parasites sont d'une importance économique/vétérinaire évidente et ceci particulièrement dans les pays tropicaux et sub-tropicaux. Tandis que l'importance deT. saginata etT. solium, sur la zoonose, a toujours été reconnue, ce n'est que récemment que l'impact deFasciola spp sur la zoonose a été repertorié.

     

Infestation of sheep with the stored product mite Sancassania berlesei (Acaridae)

A sheep reared outdoors in Victoria was found to be heavily infested with a stored product mite, Sancassania berlesei (Acaridae), apparently subsequent to an earlier flystrike. Laboratory observation revealed the infestation to be self-sustaining. Shearing rapidly resolved the infestation but treatment with diazinon was ineffective. The infestation could be transferred to other sheep only in the presence of moisture; once established it caused an extensive skin lesion with considerable fluid loss, apparently contributing to the death of one animal. This lesion was extremely attractive to blowflies. Animals infested with mites showed few signs of irritation.