Oral vaccination of brushtail possums with BCG: Investigation into factors that may influence vaccine efficacy and determination of duration of protection

AIMS: To determine factors that may influence the efficacy of an oral pelleted vaccine containing Mycobacterium bovis bacille Calmette-Guérin (BCG) to induce protection of brushtail possums against tuberculosis. To determine the duration of protective immunity following oral administration of BCG.

METHODS: In Study 1, a group of possums (n=7) was immunised by feeding 10 pellets containing dead Pasteur BCG, followed 15 weeks later with a single pellet of live Pasteur BCG. At that time, four other groups of possums (n=7 per group) were given a single pellet of live Pasteur BCG orally, a single pellet of live Danish BCG orally, 10 pellets of live Pasteur BCG orally, or a subcutaneous injection of live Pasteur BCG. For the oral pelleted vaccines, BCG was formulated into a lipid matrix, and each pellet contained approximately 10⁷ colony forming units (cfu) of BCG, while the vaccine injected subcutaneously contained 10⁶ cfu of BCG. A sixth, non-vaccinated, group (n=7) served as a control. All possums were challenged by the aerosol route with a low dose of virulent M. bovis 7 weeks after vaccination, and killed 7–8 weeks after challenge. Protection against challenge with M. bovis was assessed from pathological and bacteriological findings.

In Study 2, lipid-formulated live Danish BCG was administered orally to three groups of possums (10–11 per group), and these possums were challenged with virulent M. bovis 8, 29 or 54 weeks later. The possums were killed 7 weeks after challenge, to assess protection in comparison to a non-vaccinated group.

RESULTS: The results from Study 1 showed that vaccine efficacy was not adversely affected by feeding dead BCG prior to live BCG. Feeding 10 vaccine pellets induced a level of protection similar to feeding a single pellet. Protection was similar when feeding possums a single pellet containing the Pasteur or Danish strains of BCG. All vaccinated groups had significantly reduced pathological changes or bacterial counts when compared to the non-vaccinated group. In Study 2, oral administration of Danish BCG induced protection against challenge with M. bovis, which persisted for at least 54 weeks after vaccination. Some protection was observed in possums challenged 54 weeks after vaccination, but this protection was significantly less than that observed in groups vaccinated 29 or 8 weeks prior to challenge. There was a strong relationship between the proportion of animals producing positive lymphocyte proliferation responses to M. bovis antigens and protection against challenge with M. bovis.

CONCLUSIONS: Factors considered potentially capable of interfering with vaccination, including feeding dead BCG to possums prior to feeding live BCG, feeding multiple doses of BCG at one time, and changing strains of BCG, were shown not to interfere with the acquisition of protective immune responses in possums. Protection against tuberculosis was undiminished up to 29 weeks after vaccination with BCG administered orally. It is concluded that vaccination of possums by feeding pellets containing BCG is a robust and efficient approach to enhance the resistance of these animals to tuberculosis.     

In search of the first flower: A jurassic angiosperm, archaefructus, from northeast china

Angiosperm fruiting axes were discovered from the Upper Jurassic of China. Angiosperms are defined by carpels enclosing ovules, a character demonstrated in this fossil. This feature is lacking in other fossils reported to be earliest angiosperms. The fruits are small follicles formed from conduplicate carpels helically arranged. Adaxial elongate stigmatic crests are conspicuous on each carpel. The basal one-third of the axes bore deciduous organs of uncertain affinities. No scars of subtending floral organs are present to define the individual fertile parts as floral units, but the leaf-like structures subtending each axis define them as flowers. These fruiting axes have primitive characters and characters not considered primitive.     

Forest fires: An example of self-organized critical behavior

Despite the many complexities concerning their initiation and propagation, forest fires exhibit power-law frequency-area statistics over many orders of magnitude. A simple forest fire model, which is an example of self-organized criticality, exhibits similar behavior. One practical implication of this result is that the frequency-area distribution of small and medium fires can be used to quantify the risk of large fires, as is routinely done for earthquakes.     

Compensation of horizontal temperature and salinity gradients in the ocean mixed layer

Establishment of the temperature-salinity relationship in the ocean has concerned oceanographers for decades because of its importance for understanding ocean circulation. High-resolution measurements in the ocean mixed layer are used to show that temperature and salinity gradients on horizontal scales of 20 meters to 10 kilometers tend to compensate in their effect on density. These observations support the notion of a horizontal mixing in the mixed layer that depends on density gradient.     

Growing conditions and postharvest management can affect the essential oil of Origanum vulgare L. ssp. hirtum (Link) Ietswaart

Origanum vulgare subsp. hirtum (Link) Ietswaart (Greek oregano) has been cultivated since ancient times thanks to its herbal and therapeutic properties. Currently, it is added in various commercial preparations thanks to its essential oil composition. This group of secondary compounds is affected in quantity and quality by biotic and abiotic factors during the cultivating phase and by the postharvest management. Thus, the aims of the work were to study: (1) how the growing conditions (soil full-light treatment; pot full-light treatment; pot 50%-shade treatment) can affect the essential oil content and the essential oil profile of Greek oregano branches at full-blossoming stage; and (2) how the postharvest management (distillation of the essential oil from fresh herbs, dehumidified herbs or oven-dried herbs) can affect the essential oil content and the essential oil profile of this species. The growing conditions significantly affected the biometrical parameters. The pot full-light treatment contained the highest dry matter percentage (36.5%) and the highest essential oil content, which was directly correlated to the former parameter (r = 0.890**). The postharvest management did not affect the essential oil content. The growing condition significantly affected the characterizing γ-terpinene, cis-sabinene hydrate, 4-terpineol, α-terpinene, linalyl acetate, and β-bisabolene, while it did not affect carvacrol (mean value 15.8%), p-cymene (mean value 6.0%), or sabinene (mean value 3.9%). The postharvest management significantly affected carvacrol, cis-sabinene hydrate, 4-terpineol, p-cymene, α-terpinene, linalyl acetate, and β-bisabolene, while it did not affect γ-terpinene (mean value 14.7%). The response of some compounds to growing conditions led us to hypothesise an essential oil profile of the plants grown in pots at 50%-shade to be more of a vegetative stage type oil than the essential oil profile of the plants grown in soil, although all were at the blossoming stage. The analyses on the individual compounds indicated that, even though the essential oil content in oregano did not change with a change in postharvest management, biochemical changes occurred on the profile. These could be due to enzyme activity, dilution effect or temperature effect during the drying processes. The oven-drying process and the dehumidifying process changed the essential oil profile in a similar way compared to the essential oil profile distilled from fresh herbs. Thus, when it is not possible to extract the essential oil directly from fresh herbs, processors can dry the oregano according to the equipments they have available.     

First reports of Trichinella pseudospiralis in wild boars (Sus scrofa) of Italy

Trichinella pseudospiralis is a non-encapsulated species infecting both mammals and birds. In Italy, this parasite was reported only in two night-birds of prey of Central Italy. In January 2010, Trichinella larvae were detected in three wild boars (Sus scrofa) of two regions of Northern Italy by enzymatic digestion. The parasites were identified as T. pseudospiralis by multiplex-PCR. The first infected wild boar was hunted in the Emilia Romagna region and the other two infected wild boars were bred outdoors in a small family farm of the Friuli Venezia Giulia region. These new epidemiological data reinforce the role of the wild boar as the main reservoir of T. pseudospiralis in Europe.     

Factors associated with low vitamin D status of Australian alpacas

Objective To investigate factors associated with low vitamin D status of alpacas at pasture in southern Australia. Design A 2‐year survey of alpacas from two farms in South Australia and three in Victoria. Blood samples were collected from 20 to 30 alpacas on each farm on five occasions each year. Breed, gender, age and fleece colour of animals were recorded. Method Blood samples were assayed for plasma 2.5‐hydroxycholecalciferol (25‐OH D₃) and plasma inorganic phosphorus (Pi). Data sets from 802 animal samples were analysed by multiple regression to determine variables associated with low vitamin D status of alpacas. The relationship between plasma 25‐OH D₃ and plasma Pi was also investigated. Results Vitamin D status was significantly affected by month of sampling, with low values in late winter and high values in summer. Plasma vitamin D concentrations increased with age, were higher in alpacas with light fleeces than in those with dark fleeces and were also higher in the Suri than in the Huacaya breed. Plasma Pi concentrations were generally lower in alpacas with plasma 25‐OH D₃ values < 25 nmol/L. Conclusions Young alpacas with dark fleeces are most at risk from vitamin D insufficiency in late winter in southern Australia. The present study indicates that plasma Pi values are not a reliable indicator of vitamin D status of alpacas as assessed by plasma 25‐OH D₃ concentrations.