Effect of prior vaccination with a seasonal trivalent influenza vaccine on the antibody response to the influenza pandemic H1N1 2009 vaccine: a randomized controlled trial

Vaccination with the non-adjuvanted split-virion A/California/7/2009 influenza vaccine (pandemic H1N1 2009 vaccine) began in October 2009 in Japan. The present study was designed to assess the effect of prior vaccination with a seasonal trivalent influenza vaccine on the antibody response to the pandemic H1N1 2009 vaccine in healthy adult volunteers. One hundred and seventeen participants aged 22 to 62 were randomly assigned to two study groups. In Group 1 (the priming group), participants were first vaccinated with the seasonal trivalent influenza vaccine followed by two separate one-dose vaccinations of the pandemic H1N1 2009 vaccine, whereas in Group 2 (the non-priming group), the participants were first vaccinated with one dose of the pandemic H1N1 2009 vaccine, followed by simultaneous vaccination of the seasonal trivalent vaccine and the second dose of the pandemic H1N1 2009 vaccine. The participants in Group 2 had a seroprotection rate (SPR) of 79.7% and a seroconversion rate (SCR) of 79.7% in the hemagglutination-inhibition test after the first dose of the pandemic H1N1 2009 vaccine, indicating that the pandemic H1N1 2009 vaccine is sufficiently immunogenic. On the other hand, the participants of Group 1 had a significantly weaker antibody response, with a SPR of 60.8% and a SCR of 58.5%. These results indicate that prior vaccination with the seasonal trivalent influenza vaccine inhibits the antibody response to the pandemic H1N1 2009 vaccine. Therefore, the pandemic H1N1 2009 vaccine should be administered prior to vaccination with the seasonal trivalent influenza vaccine.     

Resistance of a rodent malaria parasite to a thymidylate synthase inhibitor induces an apoptotic parasite death and imposes a huge cost of fitness

Background

The greatest impediment to effective malaria control is drug resistance in Plasmodium falciparum, and thus understanding how resistance impacts on the parasite''s fitness and pathogenicity may aid in malaria control strategy.

Methodology/Principal Findings

To generate resistance, P. berghei NK65 was subjected to 5-fluoroorotate (FOA, an inhibitor of thymidylate synthase, TS) pressure in mice. After 15 generations of drug pressure, the 2% DT (the delay time for proliferation of parasites to 2% parasitaemia, relative to untreated wild-type controls) reduced from 8 days to 4, equalling the controls. Drug sensitivity studies confirmed that FOA-resistance was stable. During serial passaging in the absence of drug, resistant parasite maintained low growth rates (parasitaemia, 15.5%±2.9, 7 dpi) relative to the wild-type (45.6%±8.4), translating into resistance cost of fitness of 66.0%. The resistant parasite showed an apoptosis-like death, as confirmed by light and transmission electron microscopy and corroborated by oligonucleosomal DNA fragmentation.

Conclusions/Significance

The resistant parasite was less fit than the wild-type, which implies that in the absence of drug pressure in the field, the wild-type alleles may expand and allow drugs withdrawn due to resistance to be reintroduced. FOA resistance led to depleted dTTP pools, causing thymineless parasite death via apoptosis. This supports the tenet that unicellular eukaryotes, like metazoans, also undergo apoptosis. This is the first report where resistance to a chemical stimulus and not the stimulus itself is shown to induce apoptosis in a unicellular parasite. This finding is relevant in cancer therapy, since thymineless cell death induced by resistance to TS-inhibitors can further be optimized via inhibition of pyrimidine salvage enzymes, thus providing a synergistic impact. We conclude that since apoptosis is a process that can be pharmacologically modulated, the parasite''s apoptotic machinery may be exploited as a novel drug target in malaria and other protozoan diseases of medical importance.     

Novel causes of generalized glucocorticoid resistance.

Glucocorticoid resistance is a rare condition characterized by generalized, partial, target-tissue insensitivity to glucocorticoids. Compensatory elevations in circulating adrenocorticotropic hormone (ACTH) concentrations lead to increased secretion of cortisol and adrenal steroids with mineralocorticoid and/or androgenic activity, but no clinical evidence of hypercortisolism. The clinical spectrum of the condition is broad, ranging from asymptomatic to severe cases of hyperandrogenism, fatigue and/or mineralocorticoid excess. The molecular basis of glucocorticoid resistance has been ascribed to mutations in the human glucocorticoid receptor (hGR) gene, which impair glucocorticoid signal transduction, thereby altering tissue sensitivity to glucocorticoids. The study of functional defects of natural hGR mutants enhances our understanding of the molecular mechanisms of hGR action and highlights the importance of integrated cellular and molecular signaling mechanisms for maintaining homeostasis and preserving normal physiology.     

Overexpression of the genes from thermophiles in Escherichia coli by high-temperature cultivation

Twenty-nine aminotransferase genes from Pyrococcus horikoshii, Aeropyrum pernix, and Sulfolobus tokodaii were cloned and expressed in Escherichia coli. The expression of several of the genes at 15, 25, or 37 °C resulted in the formation of insoluble protein aggregates. Therefore, we developed a simple method to express these genes into soluble proteins, by cultivating E. coli clones at a higher temperature. Thus, four genes could be expressed efficiently into soluble and active enzymes by cultivating the respective E. coli clones at 46 °C. Subsequently, the method was applied to the expression into soluble proteins of other aminotransferase genes that were derived from nine species of thermophilic microorganisms.     

Biodesulfurization of Naphthothiophene and Benzothiophene through Selective Cleavage of Carbon-Sulfur Bonds by Rhodococcus sp. Strain WU-K2R

Naphtho[2,1-b]thiophene (NTH) is an asymmetric structural isomer of dibenzothiophene (DBT), and in addition to DBT derivatives, NTH derivatives can also be detected in diesel oil following hydrodesulfurization treatment. Rhodococcus sp. strain WU-K2R was newly isolated from soil for its ability to grow in a medium with NTH as the sole source of sulfur, and growing cells of WU-K2R degraded 0.27 mM NTH within 7 days. WU-K2R could also grow in the medium with NTH sulfone, benzothiophene (BTH), 3-methyl-BTH, or 5-methyl-BTH as the sole source of sulfur but could not utilize DBT, DBT sulfone, or 4,6-dimethyl-DBT. On the other hand, WU-K2R did not utilize NTH or BTH as the sole source of carbon. By gas chromatography-mass spectrometry analysis, desulfurized NTH metabolites were identified as NTH sulfone, 2′-hydroxynaphthylethene, and naphtho[2,1-b]furan. Moreover, since desulfurized BTH metabolites were identified as BTH sulfone, benzo[c][1,2]oxathiin S-oxide, benzo[c][1,2]oxathiin S,S-dioxide, o-hydroxystyrene, 2-(2′-hydroxyphenyl)ethan-1-al, and benzofuran, it was concluded that WU-K2R desulfurized NTH and BTH through the sulfur-specific degradation pathways with the selective cleavage of carbon-sulfur bonds. Therefore, Rhodococcus sp. strain WU-K2R, which could preferentially desulfurize asymmetric heterocyclic sulfur compounds such as NTH and BTH through the sulfur-specific degradation pathways, is a unique desulfurizing biocatalyst showing properties different from those of DBT-desulfurizing bacteria.