Evaluation of the goat cellular immune response to rBtuB-Hia-FlgK peptides from Brucella melitensis.

Brucellosis is a zoonosis caused by Brucella; B. melitensis is the most prevalent species in goats and humans. Previously, three B. melitensis peptides, rBtuB-Hia-FlgK showed antigen-specific immune responses in rodent models. The goal of this study was to evaluate the goat Th1/Th2 immune response to B. melitensis peptides. Twenty-eight animals were separated into four groups and were immunized with the rBtuB-Hia-FlgK peptides cocktail, adjuvant, PBS and Rev-1 vaccine, respectively. Peripheral blood samples were collected on days 0, 15, and 80 post-inoculation. The CD4+ and CD8+ T cells proliferation, and cytokine production of the Th-1 (IL-2, IL-12, TNF-α, and IFN-γ) and Th-2 profiles (IL-4, IL-5, and IL-10) were evaluated. An increase of CD4+/CD8+ at 15 days post-vaccination was observed and continued until the 80th. In addition, the IFN-γ, TNF-α, and IL-2 mRNA expression were typically induced by the 15th day, but only IFN-γ levels were observed at day 80 post-immunization. Brucella pathogenesis is distinguished by the presence of a large amount of Th-1 cytokines. Although a reduced amount of IFN-γ in the culture supernatant was accurately detected compared with Rev-1 after 15 days, it could be influenced by the sampling schedule, as a higher cytokine production might be induced as early as the first-week post-vaccination. The results indicate that rBtuB-Hia-FlgK induced an immune response similar to the Rev-1 vaccine. The possible use of inert molecules with the unique ability to typically induce cellular response similar to attenuated vaccine represents an attractive option that should not be ruled out.

Immunogenic response of Brucella canis virB10 and virB11 mutants in a murine model.

The virB locus, which encodes the type IV secretion system, is a major component of virulence in Brucella. A non-polar virB10 mutant and a virB11 deletion mutant were constructed in Brucella canis. In the mouse model, both mutants were cleared at day 21 post-infection, indicating reduced virulence in mice. After challenging with wild-type B. canis, the amounts of CFU recovered at day 15 were significantly lower in the group previously vaccinated with the virB10 mutant. Levels of IgG1, IgG2a, IgG2b, and IgM, the induction of the cytokines IL-2, IL-4, IL-10, and the production of IFN-γ were measured in lymphocyte cultures. All strains elicited similar levels of different antibody isotype profiles, and no significant differences were detected (P < 0.05). The wild-type strain induced a rapid and strong INF-γ response at 24 h, while both mutants induced mild INF-γ responses at 24 h, which remained constant over the course of sampling. Our results suggest that the virB mutants elicit a protective immunity and may be considered as candidates for studies to be conducted in dogs against canine brucellosis.

Maternal blood lead level during pregnancy in South Central Los Angeles.

Twenty-five years of public health efforts produced a striking reduction in lead exposure; the blood lead average in the United States has decreased to less than 20% of levels measured in the 1970s. However, poor minority groups that live in large urban centers are still at high risk for elevated lead levels. In this study, our data showed that pregnant immigrants (n = 1,428) who live in South Central Los Angeles--one of the most economically depressed regions of California--have significantly higher (p < .0001) blood lead levels (geometric mean = 2.3 microg/dl [0.11 micromol/l]) than 504 pregnant nonimmigrants (geometric mean = 1.9 microg/dl [0.09 micromol/l]). The most important factors associated with lower blood lead levels in both groups were younger age; more-recent date of blood sampling (i.e., decreasing secular trend); and blood sampling in mid-autumn, instead of mid-spring (i.e., seasonal trend). Blood lead levels of immigrants were strongly dependent on time elapsed since immigration to the United States; each natural log increase in years of residence was associated with an approximately 19% decrease in blood lead levels. Although blood lead means for both groups were almost the same as the estimated national average, 25 of the 30 cases of elevated blood lead (i.e., > or = 10 microg/dl [0.48 micromol/l) occurred in the immigrant group. The odds ratio (95% confidence intervals within parentheses) for having elevated blood lead levels (a) was 9.3 (1.9, 45.8) if the immigrant engaged in pica; (b) was 3.8 (1.4, 10.5) if the immigrant had low dietary calcium intake during pregnancy; and (c) was .65 (.43, .98) for every natural log unit increase of years of residence in the United States. The control of pica and dietary calcium intake may offer a means of reducing lead exposure in immigrants.

Blood lead level and blood pressure during pregnancy in South Central Los Angeles.

In many studies in which the relationship between blood pressure and blood lead level has been examined, investigators have found significant--but small--associations. There was only one previous report of a significant association of blood lead with blood pressure in pregnant women. We measured blood lead level and sitting blood pressure of 1,627 women in their third trimester of pregnancy. We eliminated subjects with known causes of hypertension. Most women (98.4%) were normotensive. We controlled for body mass index, age, and stress--among other factors--and constructed multiple-regression models of lead association with diastolic and systolic blood pressures. Immigrants (73% of total) had significantly higher blood lead levels and different blood pressures than nonimmigrants, suggesting that analysis be stratified by "immigrant, nonimmigrant" status. Positive relationships between blood lead level and blood pressure were found only for immigrants (p < or = .001). From the 5th to 95th blood-lead percentiles (0.9-6.2 microg/dl) in immigrants, systolic blood pressure increased 2.8 mm Hg, and diastolic blood pressure increased 2.4 mm Hg. Higher prior lead exposure of immigrants (97.7% from Latin countries) than nonimmigrants might explain the differential effect of these low levels of blood lead on blood pressure in nonimmigrants. Perhaps some immigrants are at higher risk than nonimmigrants for lead-associated elevated blood pressure during pregnancy, despite blood lead levels within the currently considered acceptable range.