Evaluation of a non-invasive, inhalational challenge method for rabies vaccine potency assay.

Veterinary rabies vaccines are essential for safeguarding the public from exposure to rabies virus, as vaccination of domestic animals provides a barrier between humans and wildlife reservoirs. Ensuring rabies vaccines are potent and effective is paramount in preventing human exposure to rabies virus. The National Institutes of Health (NIH) test, a mouse vaccination-challenge assay, is the most widely used and internationally recognized assay for potency testing of inactivated rabies vaccines, and it is currently considered the method of choice. In the NIH test, vaccinated mice are challenged by the intracranial (IC) route. The response to the IC challenge can be variable, which often results in invalid tests. In addition, the IC challenge-exposure raises animal welfare concerns. The objective of this study was to evaluate the intranasal route of challenge as a modification to the NIH test to reduce animal pain and suffering until harmonized requirements for in vitro testing of rabies vaccines are developed. Results confirm the intranasal route is an effective route of rabies challenge in mice. However, a valid challenge requires the use of a more concentrated inoculum, in comparison to the intracranial method.

Impact of Nutritional Risk on Self-Care Capacity: Social Support as a Source of Protection for Community-Dwelling Older Adults Living in a Rural Area.

BACKGROUND: Loss of independence is a major concern for rural older adults. Older adults living in rural areas are at an increased nutritional risk, which can lead to functional impairments in self-care capacity. Identifying factors, which have a role in sustaining rural older adults' self-care capacity, could help with maintaining independence as long as possible. OBJECTIVE: The objective of this study was to examine the effect of social support as a moderator between nutritional risk and self-care capacity. DESIGN: Cross sectional design using convenient sampling. SETTING: Rural Oklahoma counties designated as "non-metro" and having populations under 5,000. PARTICIPANTS: Participants included 171 community-dwelling older adults, 65 years of age and older. MEASUREMENTS: Data were collected using self-report surveys on self-care capacity (using the Duke Older Americans Resources and Services Procedures), social support (using the Social Provisions Scale), and nutritional risk (using the Mini-Nutritional Assessment short form). Using hierarchical linear regression techniques, data were analyzed to explore the moderating influence of social support in the association between nutritional risk and self-care capacity. RESULTS: A significant interaction emerged between nutritional risk, social support, and self-care capacity (ß = 0.20 p < 0.05). Thus, the deleterious impact of nutritional risk on self-care capacity was reduced by social support. CONCLUSIONS: Results provide further support of the "buffering-hypothesis" and have implications relative to the importance of accessible social provisions to enhance self-care capacity and quality of life among older adults residing in rural settings.

Potency testing of veterinary rabies vaccines: replacement of challenge by in vitro testing: considerations for development of alternative assays.

Vaccination of domestic animals against rabies creates a critical barrier between wildlife reservoirs and the human population. Ensuring these vaccines are potent and effective is paramount in preventing human exposure to this deadly and costly disease. The National Institutes of Health (NIH) test is, at present, the most widely used and internationally recommended potency assay for batch testing inactivated rabies vaccines. This test has numerous inherent limitations and disadvantages, including a lack of precision. The NIH test requires a large number of animals and involves unrelieved pain and suffering. A relevant in vitro assay should provide a more accurate, reproducible, rapid, safe, and humane rabies vaccine potency test.

A method to provide improved dose-response estimates for airborne pathogens in animals: an example using porcine reproductive and respiratory syndrome virus.

This paper describes a method to provide improved probability estimates that exposure to a specific dose of an airborne infectious pathogen will result in animal infection. Individual animals were exposed to a specific dose of airborne pathogen. Following exposure, animals were individually housed and monitored for evidence of infection. The detection of specific antibodies and/or the pathogen in diagnostic specimens was evidence that the exposure dose resulted in infection. If replicated over a range of doses, the results can be used to derive a dose-response curve for a variety of animal species and infectious pathogens. This information is useful in estimating the likelihood of infection associated with exposure to airborne infectious microorganisms. Applications include predicting the risk of transmission associated with exposure to airborne pathogens, modeling the transmission of airborne pathogens, and determining requirements for effective exposure doses for vaccines delivered in aerosols.

The United States pork niche market phenomenon.

After the broad industrialization of the US pork industry, there has been a development of niche markets for export and domestic pork; that is, there is a pork niche market phenomenon. The US pork niche market phenomenon is characterized, and 2 of the major markets are explained in detail. With the Midwest's tradition of a diversified family-based agriculture and record low hog prices of the late 1990s, the conditions were conducive for this phenomenon to develop. Pork niche markets utilize various sales methods including Internet sales, local abattoir sales, direct marketing, farmer networks, and targeting to organized groups. In 2003, there were approximately 35 to 40 active pork niche marketing efforts in Iowa. The Berkshire breed is an example of a swine breed that has had a recent resurgence because of niche markets. Berkshire pork is known for tenderness and excellent quality. Berkshire registrations have increased 4-fold in the last 10 yr. One of the larger niche marketers of "natural pork" is Niman Ranch Pork, which has more than 400 farmer-producers and processes about 2,500 pigs weekly. Many US consumers of pork are interested in issues concerning the environment, food safety, pig welfare, and pig farm ownership and structure. These consumers may be willing to pay more for pork from farmers who are also concerned about these issues. Small- and medium-sized swine farmers are active in pork niche markets. Niche markets claim product differentiation by superior or unique product quality and social attributes. Quality attributes include certain swine breeds, and meat quality, freshness, taste or flavor, and tenderness. Social or credence attributes often are claimed and include freedom from antibiotics and growth promotants; local family farm production; natural, organic, outdoor, or bedded rearing; humane rearing; known origin; environmentally friendly production; and the absence of animal by-products in the feed. Niche pork markets and alternative swine production practices offer an unusual contrast to commodity pork markets and industrial confinement swine production. Because they strive to have these attributes in their product, the niche pork market producers are a distinct clientele group. If niche pork markets continue to flourish, the markets and the producers that supply them will be a viable sector in a diverse US pork industry.

Optimization of a sampling system for recovery and detection of airborne porcine reproductive and respiratory syndrome virus and swine influenza virus.

The objective of this research was to optimize sampling parameters for increased recovery and detection of airborne porcine reproductive and respiratory syndrome virus (PRRSV) and swine influenza virus (SIV). Collection media containing antifoams, activated carbons, protectants, and ethylene glycol were evaluated for direct effects on factors impacting the detection of PRRSV and SIV, including virus infectivity, viability of continuous cell lines used for the isolation of these viruses, and performance of reverse transcriptase PCR assays. The results showed that specific compounds influenced the likelihood of detecting PRRSV and SIV in collection medium. A subsequent study evaluated the effects of collection medium, impinger model, and sampling time on the recovery of aerosolized PRRSV using a method for making direct comparisons of up to six treatments simultaneously. The results demonstrated that various components in air-sampling systems, including collection medium, impinger model, and sampling time, independently influenced the recovery and detection of PRRSV and/or SIV. Interestingly, it was demonstrated that a 20% solution of ethylene glycol collected the greatest quantity of aerosolized PRRSV, which suggests the possibility of sampling at temperatures below freezing. Based on the results of these experiments, it is recommended that air-sampling systems be optimized for the target pathogen(s) and that recovery/detection results should be interpreted in the context of the actual performance of the system.

Probability of porcine reproductive and respiratory syndrome (PRRS) virus infection as a function of exposure route and dose.

At the most elemental level, the design of effective strategies to control and/or eliminate porcine reproductive and respiratory syndrome (PRRS) virus depend on an accurate and comprehensive understanding of virus transmission. As a general rule, transmission is highly dependent on the route of exposure and the dose of virus. The objective of this study was to derive PRRS virus isolate VR-2332 dose-response curves for oral and intranasal routes of exposure, i.e., determine the probability that a specific virus dose would result in infection. Individually housed pigs approximately 21 days of age were exposed to specific doses of PRRS virus isolate VR-2332 by either oral or intranasal routes. Positive controls were intramuscularly inoculated with 10(2.2) 50% tissue culture infective dose (TCID50) of PRRS virus and negative controls were orally administered 100ml of diluent with no virus. Pigs were monitored for evidence of infection for 21 days following exposure, i.e., serum samples were collected on days 0, 7, 14, 21, and tested for virus and PRRS virus-specific antibodies. Dose-response curves and 95% confidence intervals for oral and intranasal routes of exposure were derived using logistic models (logit and probit). The infectious dose50 (ID50) for oral exposure was estimated to be 10(5.3) TCID50 (95% CI, 10(4.6) and 10(5.9)); the ID50 for intranasal exposure was estimated to be 10(4.0) TCID50 (95% CI, 10(3.0) and 10(5.0)). Given these estimates, it is worth noting that intramuscular exposure of animals to 10(2.2) TCID50 (positive controls) resulted in infection in all animals. Thus pigs were the most susceptible to infection via parenteral exposure.

Effect of dietary Echinacea purpurea on viremia and performance in porcine reproductive and respiratory syndrome virus-infected nursery pigs.

The effect of dietary Echinacea purpurea on performance, viremia, and ontogeny of the humoral antibody response against porcine reproductive and respiratory syndrome virus (PRRSV) infection was evaluated in weaned pigs. In three replicates, 120 weaned pigs (25 +/- 1 d of age; 8.46 +/- 0.48 kg of BW) from a PRRSV-naive herd were allotted randomly to one of eight pens (diets) in two separate rooms (four pens/room), with each pen containing five pigs. Pigs began one of four dietary treatments (as-fed basis) 1 wk before inoculation with PRRSV: 1) basal diet composed of corn, soybean meal, whey, and essential vitamins and minerals; 2) basal diet plus carbadox (0.055 g/kg of diet; as-fed basis); 3) basal diet plus Echinacea 2% (2% of the total diet); 4) basal diet plus Echinacea 4% (4% of the total diet). The diets were formulated to be isocaloric and isolysinic. Echinacea purpurea was purchased in powder form and determined by chemical analysis to contain 1.35% cichoric acid (as-fed basis). Seven days after starting the diets, all pigs in one room were intranasally inoculated with PRRSV isolate ATCC VR-2332 at a concentration of 10(4) tissue culture infectious dose50/mL. To monitor the effects of Echinacea and PRRSV challenge, BW and blood samples were obtained from all pigs at 7-d intervals. Serum samples were analyzed for the presence of PRRSV and PRRSV-specific antibodies. All challenged pigs became infected with PRRSV, and all unchallenged pigs remained free of infection. No differences (P > 0.10) in ADG, ADFI, or gain:feed (G:F) were observed in PRRSV-challenged compared with unchallenged animals. For PRRSV-challenged animals receiving diets supplemented with Echinacea at 2 or 4%, no differences (P > 0.10) were observed in ADG, ADFI, or G:F ratio. Among PRRSV-challenged pigs, dietary Echinacea did not affect (P > 0.10) the rate or level of the ELISA-detectable antibody response from d 7 to 42 or the level and duration of PRRSV in serum. For PRRSV-unchallenged animals receiving diets supplemented with Echinacea at 2 or 4%, no differences (P > 0.10) were observed in ADG, ADFI, and G:F ratio. Under the conditions of this study, dietary Echinacea did not enhance growth, exhibit antiviral effects to PRRSV, or show any evidence of immune enhancing properties.

The effects of chromium and copper supplementation on mitogen-stimulated T cell proliferation in hypercholesterolaemic postmenopausal women.

The purpose of this study was to analyse effects of chromium and/or copper supplementation on immune function in hypercholesterolaemic postmenopausal women. A 2 x 2 factorial research design was used and 40 subjects were supplemented with 0.394 g lactose, 200 microg Cr, 3.0 mg Cu, or 200 microg Cr and 3.0 mg Cu/d for 12 weeks. A significant interactive effect of Cr and Cu supplementation on lymphocyte proliferation was observed with ConA 50 microg/ml stimulation. After 12 weeks of supplementation, ConA-stimulated (50 microg/ml) lymphocyte proliferation was significantly lower when Cu was added to the Cr supplementation group. Moreover, ConA-stimulated (100 microg/ml) lymphocyte proliferation was significantly lower in the Cu supplementation group compared to the Cr supplementation group after 12 weeks of supplementation. These results suggest that Cu blocks enhancement of lymphocyte proliferation by Cr supplementation and that Cu supplementation has potential suppressive effects on the immune function in these subjects.

Fiber intake of older adults: relationship to mineral intakes.

This study evaluated reported dietary fiber and mineral intakes of 45 healthy adults, 60 years and over, using two sets of three-day dietary food records. The average age of the participants was 73 years, with an age range of 60 to 87 years. Mean reported dietary fiber intake was 18.3 g per day. Percentage of dietary fiber from different food sources was; breads and cereals 33%, vegetables 22%, fruits 21%, beans and legumes 7%, nuts and seeds 3%, combination foods 7% and others 7%. Significant positive correlations were observed between dietary fiber intake and copper, magnesium, selenium, potassium, iron and zinc intakes. Those participants with dietary fiber intakes of 20 g/day or more had significantly higher intakes of copper, magnesium, selenium, potassium and iron compared to those who had dietary fiber intakes less than 20 g/day, although mean kilocalorie intakes were not significantly different. Thus, increasing grain products, vegetables and fruits to increase dietary fiber intake, also may improve the mineral intakes of older adults.