The immunogenicity and tissue reactivity of Mycobacterium avium subsp paratuberculosis inactivated whole cell vaccine is dependent on the adjuvant used

Johne's disease (JD) is a chronic enteritis caused by Mycobacterium avium subspecies paratuberculosis (MAP). Current commercial vaccines are effective in reducing the occurrence of clinical disease although vaccinated animals can still become infected and transmit MAP. Many vaccinated sheep develop severe injection site lesions. In this study a range of adjuvants (Montanide^TM ISA 50V, ISA 50V2, ISA 61VG, ISA 70 M VG, ISA 71 VG, ISA 201 VG and Gel 01 PR) formulated with heat-killed MAP were tested to determine the incidence of injection site lesions and the types of immune profiles generated in sheep. All the novel formulations produced fewer injection site lesions than a commercial vaccine (Gudair®). The immune profiles of the sheep differed between treatment groups, with the strength of the antibody and cell mediated immune responses being dependant on the adjuvant used. One of the novel vaccines resulted in a reduced IFN-γ immune response when a second “booster” dose was administered. These findings have significance for JD vaccine development because it may be possible to uncouple protective immunity from excessive tissue reactivity, and apparently poorly immunogenic antigens may be re-examined to determine if an appropriate immune profile can be established using different adjuvants. It may also be possible to formulate vaccines that produce targeted immunological profiles suited to protection against other pathogens, i.e. those for which a bias towards cellular or humoral immunity would be advantageous based on understanding of pathogenesis.

Sheep and cattle exposed to Mycobacterium avium subspecies paratuberculosis exhibit altered total serum cholesterol profiles during the early stages of infection

Pathogenic mycobacteria such as Mycobacterium tuberculosis are capable of utilising cholesterol as a primary carbon-based energy source in vitro but there has been little research examining the significance of cholesterol in vivo. Johne's disease is a chronic enteric disease of ruminants caused by Mycobacterium avium subspecies paratuberculosis (MAP). This study sought to evaluate the levels of total serum cholesterol in the host following exposure to MAP. Blood samples were collected from both sheep and cattle prior to experimental challenge with MAP and at monthly intervals post-challenge. Total serum cholesterol levels in sheep challenged with MAP were significantly elevated at 9 weeks post-inoculation (wpi) in comparison to controls. When stratified based on disease outcome, there was no significant difference in serum cholesterol at the timepoints examined between MAP exposed sheep that were susceptible and those that were resistant to Johne's disease. There was a similar elevation in serum cholesterol at 9 wpi in cattle with histopathological gut lesions associated with disease or those with an early high IFN-γ response. Total serum cholesterol in exposed cattle was significantly lower when compared to controls at 13 wpi. Taken together, these results demonstrate changes in serum cholesterol following MAP exposure and disease progression which could reflect novel aspects of the pathogenesis and immune response associated with MAP infection in both sheep and cattle.

Case definition terminology for paratuberculosis (Johne's disease)

Paratuberculosis (Johne's disease) is an economically significant condition caused by Mycobacterium avium subsp. paratuberculosis. However, difficulties in diagnosis and classification of individual animals with the condition have hampered research and impeded efforts to halt its progressive spread in the global livestock industry. Descriptive terms applied to individual animals and herds such as exposed, infected, diseased, clinical, sub-clinical, infectious and resistant need to be defined so that they can be incorporated consistently into well-understood and reproducible case definitions. These allow for consistent classification of individuals in a population for the purposes of analysis based on accurate counts. The outputs might include the incidence of cases, frequency distributions of the number of cases by age class or more sophisticated analyses involving statistical comparisons of immune responses in vaccine development studies, or gene frequencies or expression data from cases and controls in genomic investigations. It is necessary to have agreed definitions in order to be able to make valid comparisons and meta-analyses of experiments conducted over time by a given researcher, in different laboratories, by different researchers, and in different countries. In this paper, terms are applied systematically in an hierarchical flow chart to enable classification of individual animals. We propose descriptive terms for different stages in the pathogenesis of paratuberculosis to enable their use in different types of studies and to enable an independent assessment of the extent to which accepted definitions for stages of disease have been applied consistently in any given study. This will assist in the general interpretation of data between studies, and will facilitate future meta-analyses.

Variation in susceptibility of different breeds of sheep to Mycobacterium avium subspecies paratuberculosis following experimental inoculation

Exposure to Mycobacterium avium subspecies paratuberculosis (MAP) does not always lead to Johne’s disease. Understanding differences in disease susceptibility of individual animals is a key aspect to controlling mycobacterial diseases. This study was designed to examine the susceptibility or resistance of various breeds of sheep to MAP infection. Merino, Suffolk first cross Merino, Border Leicester, and Poll Dorset sheep were orally inoculated with MAP and monitored for 14 months. Clinical disease occurred more frequently in the Merino (42%) and Suffolk first cross Merino (36%) compared to the Border Leicester (12%) and Poll Dorset (11%) breeds. Infection risk, as determined by culture of gut and associated lymphoid tissues, ranged from 75% for the Suffolk first cross Merino to 47% for the Poll Dorset sheep. Significant differences were identified in the site in the intestines of the most severe histopathological lesions and the immune responses to infection between the breeds. However, there was no difference in faecal MAP shedding by clinical cases between breeds. All breeds tested were susceptible to MAP infection, as determined by infection and clinical disease development, although there were differences in the proportions of diseased animals between the breeds. Poll Dorset and Border Leicester sheep were more resilient to MAP infection but there was evidence that more animals could have developed disease if given more time. These findings provide evidence of potential differential disease susceptibility between breeds, further our understanding of disease pathogenesis and risks of disease spread, and may have an influence on control programs for paratuberculosis.

Applying the One Health Concept to Mycobacterial Research - Overcoming Parochialism

Mycobacterial infections remain a public health problem. Historically important, globally ubiquitous and with a wide host range, we are still struggling to control mycobacterial infections in humans and animals. While previous reviews have focused on individual mycobacterial infections in either humans or animals, a comprehensive review of the zoonotic aspect of mycobacteria in the context of the One Health initiative is lacking. With the purpose of providing a concise and comprehensive resource, we have collated literature to address the zoonotic potential of different mycobacterial species and elaborate on the necessity for an inter-sectorial approach to attain a new vision to combat mycobacterial infections.

Effects of initial body mass index on development of gestational diabetes in a rural Sri Lankan population: A case-control study

AIM

High pre-pregnancy body mass index (BMI) and excessive pregnancy weight gain lead to higher incidence of gestational diabetes mellitus (GDM). Aim of the study was to assess the effects of initial BMI and pregnancy weight gain on development of GDM in a rural Sri Lankan population. It was also hypothesized that these effects could be more pronounced in shorter mothers.

METHODS

A case-control study was conducted at two rural hospitals in Sri Lanka. A case was defined as a pregnant mother admitted for the completion of pregnancy and diagnosed to have GDM (n=99). A similar group of mothers without GDM were recruited as controls (n=336). Data were collected through health records and direct interviews.

RESULTS

Mean age of GDM and non-GDM mothers were 32.8 years 28.1 years, respectively. High pre-pregnancy BMI was a significant risk for GDM, with a rising trend with increasing BMI. In contrast to underweight mothers, the risk increases from normal weight [odds ratio (OR)=6.6, 95% confidence interval (CI) 2.2-19.4, p<0.01], overweight (OR=17.1, 95% CI 5.8-49.9, p<0.01) and to obese (OR=32.4, 95% CI 10.0-104.5, p<0.01). There was no significant difference in weight gain across mother's height groups. Height or leg length did not show an association with GDM. Family history of diabetes and past GDM were associated with GDM. GDM mothers had higher likelihood for cesarian deliveries, and babies with higher birth weight.

CONCLUSION

The pre-pregnancy BMI was the most important modifiable risk factor for GDM, and it should be the main preventive measure.

Does a Th1 over Th2 dominancy really exist in the early stages of Mycobacterium avium subspecies paratuberculosis infections?

The immune response of ruminants to Johne's disease has been long associated with a cell mediated immune (CMI) response in the early stages of infection with a switch to an antibody response later as the disease manifests. This study examines the immune response in sheep to Mycobacterium avium subspecies paratuberculosis (Map) infections, specifically the antigen-specific interferon gamma (IFN-γ) and antibody responses as surrogates of T helper-1 (Th1) and Th2 immunity. The difference in IFN-γ production between paucibacillary and multibacillary diseased animals was also examined. The results show that sheep are more likely to have a combined antibody and IFN-γ response (seen in 50% of the animals) rather than a switch from an IFN-γ to antibody response (39%). Multibacillary diseased animals were found to have a decrease in functional ability to produce IFN-γ from cells stimulated with MAP-specific antigens and non-specific mitogens. This indicates that the immune responses to Map infections are more complex than thought, where both antibody and cellular immunity may play key roles in the early stages of disease manifestation or resistance. The loss of the cellular response in multibacillary animals may be an indication that the entire immune response is dysfunctional, with the cell mediated responses becoming affected first.

A fatal case of phlegmonous colitis in chronic hepatitis C receiving combination interferon and ribavirin therapy

Phlegmonous colitis is an acute suppurative infection of the large bowel that is rarely described, rapidly fatal and often escapes clinical attention. Patients with chronic hepatic diseases appear to be predisposed to this condition. We report a novel case of fatal phlegmonous colitis in a cirrhotic patient receiving combination pegylated interferon and ribavirin for chronic hepatitis C, highlighting the importance of early recognition of this aggressive infectious entity.

Workplace factors: The key to successful and sustained continuation of a general practice-based smoking cessation programme

Health promotion activity such as smoking cessation is now expected in primary care settings, including general practice. However, successful implementation and continuation of health promotion programmes is often difficult to achieve in any consistent way across a locality. This study aimed to investigate factors associated with implementation and maintenance difficulties for a smoking cessation programme in primary care, despite the provision of well-received training and support for practice nurses and general practitioners. A descriptive evaluation using numerical data and semi-structured interviews was used for general practices in the Wellington region of New Zealand during 2001-2002. The Can Quit Practice smoking cessation programme was developed and made available to all 114 general practices in the Wellington area. Data were collected and interviews conducted about implementation and ongoing programme delivery. One-third (39/114, 34%) of practices accepted and completed training for at least one staff member, usually a practice nurse. Subsequently, only 44% of practices (17/39) went on to achieve full programme implementation. Key factors precluding implementation included inadequate funding for practice nurse and general practitioner time, high patient workloads, lack of practice nurse autonomy and limited practice-wide commitment to smoking cessation. Unfavourable workplace factors can preclude the successful implementation and maintenance of an effective smoking cessation programme for patients, even when health professionals are aware of the benefits of smoking cessation, recognise the worth of offering such programmes, and receive acceptable training and ongoing support at no cost.

Bone marrow stem cell and progenitor response to injury

Hematopoietic stem cells represent a long term reservoir of cells to populate blood with multiple formed cells. These hematopoietic stem cells proliferate and mature into lymphoid, erythroid, and myeloid precursor cells, with the balance of these cell populations modulated by major thermal injury, with or without sepsis. Recent studies indicate that thermal injury shifts this balance to favor the monocyte/macrophage lineage at the expense of neutrophil production. The mechanisms for these changes are now being elucidated with the results of clinical importance, because understanding the dynamics of the different precursor pools could be used to identify patients at greater risk for systemic inflammatory sequelae following major thermal injury.

Use of water-miscible retinyl palmitate as markers of chylomicrons gives earlier peak response of plasma retinyl esters compared with oil-soluble retinyl palmitate

Delayed peak response of plasma retinyl esters (RE) relative to plasma triacylglycerols (TAG) and apolipoprotein (Apo) B-48 responses following a fat load supplemented with vitamin A raised doubts about the use of vitamin A to label dietary-derived lipids and lipoproteins. The present study compared the use of water-miscible and oil-soluble retinyl palmitate (RP) as markers of dietary-derived lipoproteins in healthy subjects along with the measurements of postprandial plasma TAG and ApoB-48 responses to investigate whether the delayed peak response observed was due to delayed intestinal output of RE from oil-based solutions. Nine healthy female subjects were given a standard test meal containing a dose (112 mg) of RP in either water-miscible or oil-soluble form in random order, on two separate occasions after a 12 h overnight fast. The results showed that the mean plasma RE concentrations reached a peak significantly later than mean plasma TAG and ApoB-48 concentrations when oil-soluble RP was consumed, whereas plasma RE peaked earlier relative to plasma TAG and ApoB-48 responses when water-miscible RP was used. The results suggested a more rapid absorption with a significantly higher and earlier peak response of plasma RE when water-miscible RP was consumed. This was in contrast to the delayed initial appearance and later sustained higher concentrations of plasma RE during the late postprandial period when oil-soluble RP was consumed. The RE response to the water-miscible RP showed better concordance with plasma TAG response than that of oil-soluble RP.

5,5-Diaryl-2-amino-4-pentenoates as novel, potent, and selective glycine transporter type-2 reuptake inhibitors

A novel series of 5,5-diaryl-2-amino-4-pentenoates was synthesized and found to be potent and selective glycine transporter type-2 reuptake inhibitors.