Characterization Based on the 56-Kda Type-Specific Antigen Gene of Orientia tsutsugamushi Genotypes Isolated from Leptotrombidium Mites and the Rodent Host Post-Infection

Characterization of the 56-kDa type-specific antigen (TSA) genes of Orientia tsutsugamushi (OT) from three naturally infected, laboratory-reared mite colonies comprising three species (Leptotrombidium deliense [Ld], Leptotrombidium imphalum [Li], and Leptotrombidium chiangraiensis [Lc]) has revealed the presence of single and coexisting OT genotypes found in individual chiggers. The Karp genotype was found in all of the chiggers examined, whereas Gilliam and UT302 genotypes were only observed in combination with the Karp genotype. From analysis of these OT genotypes after transmission from chiggers to mice it was determined that with the Lc and Li mites, the OT genotype composition in the rodent spleens post-infection had not changed and therefore resembled that observed in the feeding chiggers. However, only the Karp genotype was found in rodents after feeding by Ld chiggers carrying Karp and Gilliam genotypes. The current findings reveal a complex association among the host, pathogen, and vector.     

Training enhances vascular relaxation after chemotherapy-induced vasoconstriction

PURPOSE: Although evidence is accumulating that suggests regular moderate physical activity improves physiological and psychological well-being of cancer patients undergoing chemotherapy, the mechanisms involved remain unclear. Therefore, the purpose of this study was to determine if exercise training improves endothelium-dependent vasodilation after exposure to the chemotherapeutic agent 5-fluorouracil (5-FU). METHODS: Rats were injected with N-methyl-N-nitrosourea (MNU) and assigned to either exercise (EX; treadmill running, 20-25 m.min(-1) grade, 30 min.d(-1), 5 d.wk(-1) for 8 wk) or sedentary (SED) groups. After the exercise training period, aortic rings were obtained and used to assess contractile and relaxation characteristics. In addition, endothelial nitric oxide synthase (eNOS) protein content and eNOS enzyme activity was determined. RESULTS: Exercise training resulted in increased maximal endothelium-dependent vasorelaxation to acetylcholine (ACh, 1 x 10(-5) M) (SED, 56 +/- 3%; exercise, 71 +/- 5%; P < 0.05) after norepinephrine-induced (1 x 10(-7) M) vasoconstriction. Exposure of aortic rings from each group to increasing concentrations of 5-FU (7 x 10(-5) x 10 M(-3)) resulted in vasoconstriction. Rings obtained from exercise-trained animals demonstrated enhanced vasorelaxation to ACh (1 x 10(-5) M) after 5-FU-induced vasoconstriction compared with rings obtained from SED animals (P < 0.05). In addition, exercise training enhanced eNOS protein content and eNOS activity. CONCLUSION: Exercise training enhances endothelium-dependent vasorelaxation after 5-FU-induced vasoconstriction, and this may be due, at least in part, to an increase in aortic eNOS protein content and activity. Such exercise-induced adaptations may help alleviate chemotherapy-related fatigue observed in cancer patients.     

CpG DNA, liposome and refined antigen oral cholera vaccine

An oral cholera vaccine made up of three Vibrio cholerae antigens, i.e. lipopolysaccharide (LPS), recombinant toxin co-regulated pili (rTcpA) and heat-treated cholera toxin (H-CT) has been developed in six different formulations. Eight-week-old Wistar rats were divided into nine groups and immunized as follows: the first group received the oral vaccine 1 consisting of the three antigens (LPS, rTcpA and H-CT) associated with a liposome (L) and bacterial CpG-DNA (ODN#1826). The rats of groups 2 and 3 received oral vaccines 2 and 3 consisting of the liposome-associated three antigens with and without non-bacterial CpG-DNA (ODN#1982), respectively. Rats of groups 4 received oral vaccine 4 consisting of the three antigens mixed with the ODN#1826, similar to vaccine 1, but without liposome. Rats of groups 5 and 6 received oral vaccines 5 and 6 consisting of the three antigens with and without ODN#1982, respectively, similar to vaccines 2 and 3, but without liposome. Rats of groups 7, 8 and 9 received oral placebos, namely liposomes (L), ODN#1826 (CpG), and vaccine diluent, i.e. 5% NaHCO3 solution, respectively. All vaccines were given in three doses at 14-day intervals. It was found that the combination of liposome and ODN#1826 in vaccine 1 evoked the highest immune response to V. cholerae antigen compared to other vaccine formulations and placebos, as measured by the appearance of antigen-specific antibody-producing cells in the intestinal lamina propria. The immunogenicity according to the magnitude of the immune response was: V1>V2=V3>V4>V5=V6>V7=V8=V9. The results of this study indicate that CpG-DNA and liposome are effective mucosal adjuvants for an oral cholera vaccine prepared from refined V. cholerae antigens and their combination seems to be synergistic. The potential role of liposome as a vaccine delivery vehicle has been confirmed.     

Comparison of humoral and cellular immune responses to a pentavalent modified live virus vaccine in three age groups of calves with maternal antibodies,before and after BVDV type 2 challenge

The aim of this study was to evaluate the ability of a pentavalent (BVDV types 1 and 2, BHV-1, BRSV, and PI-3) modified live virus (MLV) vaccine given to 1–2-, 4–5-, and 7–8-week-old calves with maternal antibodies to induce humoral and cellular immune responses and protect calves from virulent BVDV type 2. Eight calves in each age group were vaccinated and four served as controls. All calves were challenged intranasally with BVDV type 2, 12 weeks after vaccination. SVN titers to all five viruses declined in all groups after vaccination (except 4–5-week-old calves to BVDV type 1). After challenge, the SVN titers for both types of BVDV showed anamnestic responses in calves vaccinated at 4–5 and 7–8 weeks, but not at 1–2 weeks of age. In all groups, T cell subsets responded specifically to BVDV types 1 and 2 but not to BHV-1, BRSV, or PI-3 after vaccination by increasing their expression of activation markers (CD25, IFN-γ and IL-4). All vaccinated calves were significantly protected from BVDV type 2 challenge.     

Vaccination with NS1-truncated H3N2 swine influenza virus primes T cells and confers cross-protection against an H1N1 heterosubtypic challenge in pigs

The diversity of contemporary swine influenza virus (SIV) strains impedes effective immunization of swine herds. Mucosally delivered, attenuated virus vaccines are one approach with potential to provide broad cross-protection. Reverse genetics-derived H3N2 SIV virus with truncated NS1 (NS1Δ126 TX98) is attenuated and immunogenic when delivered intranasally in young pigs. We analyzed T-cell priming and cross-protective efficacy in weanling piglets after intranasal inoculation with NS1Δ126 TX98 versus wild type TX98. In vivo replication of the truncation mutant was minimal compared to the wild type virus. T-cell responses were greater in magnitude in pigs infected with the wild type virus in in vitro restimulation assays. According to the expression of activation marker CD25, peripheral T cell recall responses in NS1Δ126 TX98 infected pigs were minimal. However, intracellular IFN-γ data indicate that the attenuated virus induced virus-specific CD4⁺CD8^-, CD4⁺CD8⁺, CD4^-CD8⁺, and γδ T cells within 28 days. The IFN-γ response appeared to contract, as responses were reduced at later time points prior to challenge. CD4⁺CD8⁺ cells isolated 5 days after heterosubtypic H1N1 challenge (day 70 overall) showed an elevated CD25 response to virus restimulation. Pigs previously infected with wild type TX98 were protected from replication of the H1N1 challenge virus. Vaccination with NS1Δ126 TX98 was associated with significantly lower levels of Th1-associated cytokines in infected lungs but provided partial cross-protection against the H1N1 challenge. These results demonstrate that NS1Δ SIV vaccines can elicit cell-mediated cross-protection against antigenically divergent strains.     

Synergistic effect of vancomycin combined with cefotaxime,imipenem, or meropenem against Staphylococcus aureus with reduced susceptibility to vancomycin

Background/aim We investigated the synergistic effect between vancomycin and β-lactams against vancomycin-susceptible (VSSA) and nonsusceptible MRSA isolates [heterogeneous vancomycin-intermediate S. aureus (hVISA) and VISA].Materials and methods A total of 29 MRSA, including 6 VISA, 14 hVISA, and 9 VSSA isolates, were subjected to a microbroth dilution-minimum inhibitory concentration (MIC) checkerboard using vancomycin combined with cefotaxime, imipenem, or meropenem. To confirm synergistic activity, the representative strains of VISA, hVISA, and VSSA were then selected for the time-kill curve method.Results The combination of vancomycin with imipenem, meropenem, or cefotaxime exhibited synergistic effects against 17 (2 VISA, 9 hVISA, and 6 VSSA), 14 (3 VISA, 9 hVISA and 2 VSSA), and 5 (3 VISA and 2 hVISA) isolates, respectively. Additive and indifferent effects were found in the remaining isolates, but no antagonistic effect was observed. Using time-kill assay, the vancomycin combined with either imipenem or cefotaxime demonstrated synergism against both VISA and hVISA isolates, while the synergistic effect with meropenem was obtained only in the VISA isolates.Conclusion This study demonstrated in vitro enhanced antibacterial activity of vancomycin plus β-lactams against clinical hVISA or VISA isolates. These combinations may be an alternative treatment for MRSA infections in clinical practice.     

Delayed visual maturation in Karen refugee infants

Thirty-eight babies born to Karen mothers living in camps for displaced persons in north-western Thailand have delayed visual maturation (DVM type 1) that recovers within 6 months. Vitamin A concentrations were deficient in 16% of breast-milk samples from lactating mothers and vitamin B(1) concentrations were deficient in 60% of plasma samples. Infantile beriberi was common in this population. The levels of fatty acids in plasma and milk in Karen women were excellent at birth and in the postpartum period. The degree of deficiencies in these vitamins and the concentration of essential fatty acids in cord blood and maternal breast-milk did not correlate significantly with visual impairment in the infants. DVM might be caused by nutritional deficiency or toxic effects during critical periods of gestation that lead to delayed cortical myelination or structural defects which impinge on parietal cortex function.     

Chloroquine prophylaxis against vivax malaria in pregnancy: a randomized, double-blind, placebo-controlled trial

OBJECTIVE: To assess the safety of chloroquine (CQ) as prophylaxis against Plasmodium vivax infection during pregnancy. METHOD: One thousand pregnant Karen women were enrolled in a randomized, double-blind, placebo-controlled trial of chemoprophylaxis with chloroquine (500 mg phosphate (or 300 mg base) weekly). Women received a median (range) chloroquine phosphate total dose of 9500 (1500-17 500) mg. The mothers were actively followed from inclusion to delivery and their infants until 12 months of age. RESULTS: Chloroquine prophylaxis completely prevented P. vivax episodes; 10.1% (95%CI: 7.3-14.5) of women in the placebo group experienced at least one episode of vivax malaria but no episode occurred in women in the CQ group. By contrast, the numbers of P. falciparum episodes were similar in each group: 7.4% (95%CI: 3.7-11.1) and 5.6% (95%CI: 3.3-7.9) in the placebo and CQ groups respectively (P = 0.56). Chloroquine prophylaxis was well tolerated and there was no difference in the proportions of reported side effects between CQ treated and placebo groups except for the duration of palpitations and sleeping disorders which were more frequent in those who had received CQ. Chloroquine prophylaxis had no impact on maternal anaemia, birth weight, gestational age, development of newborns or on growth, neurological development or visual acuity in infants at 1 year of age. CONCLUSION: Chloroquine is safe and effective as prophylaxis against P. vivax during pregnancy in this population.     

Double infection of heteroserotypes of dengue viruses in field populations of Aedes aegypti and Aedes albopictus (Diptera: Culicidae) and serological features of dengue viruses found in patients in southern Thailand

In order to understand more about the epidemiology of DHF, a study of the type of dengue viruses and vectors under natural conditions was carried out. Mosquito vectors in the field and the serum of DHF patients in southern Thailand were examined. The two mosquito species are abundant and DHF incidence remains high in this region. Dengue viruses were examined in field-caught mosquitoes by RT-PCR technique. The mosquitoes were caught in 4 provinces: Krabi, Phuket, Phang-Nga and Surat Thani during the late dry season until the early rainy season in 2005. Three dengue serotypes (DEN-2, DEN-3, DEN-4) were detected in Ae. aegypti males and females, and 2 (DEN-2, DEN-3) were detected in Ae. albopictus females. Double infection with 2 serotypes of dengue viruses (DEN-2 and DEN-3) were detected in Ae. aegypti males and females and Ae. albopictus females. DEN-2 and DEN-1 were the most prevalent serotypes found in the serum of the patients in this area, followed by DEN-4 and DEN-3. The prevalence of the predominant dengue serotype varied from province to province. Detection of viruses in adult male mosquitoes reveals the role of transovarial transmission of dengue viruses in field populations of DHF vectors and elucidates circulation of dengue viruses in vectors in the natural environment of endemic areas. The incidence of multiple serotypes of dengue virus in Ae. aegypti and Ae. albopictus in the same area points toward a high risk for an epidemic of DHF. These findings provide greater understanding of the relationship among mosquito vectors, virus transmission and DHF epidemiology in endemic areas.