Background: The involvement of the storage mite Tyrophagus putrescentiae in allergies has been increasingly reported in many countries. Molecular analysis has shown that group 3 mite allergens are homologous to trypsin. Similar allergens have not been identified in T. putrescentiae. Our aims were to characterize group 3 allergens in T. putrescentiae and to investigate their significance in allergenicity. Methods: cDNAs of PreTyr p 3 and rTyr p 3 from T. putrescentiae were cloned and expressed in Escherichia coli. Native Tyr p 3 (nTyr p 3) was purified from spent growth medium with an affinity column coupling of antibody. Biological activities of rTyr p 3 were compared with nTyr p 3 in terms of IgE activity, enzymatic activity and histamine release. Results: Full-length cDNA of PreTyr p 3 encodes a 285-amino acid trypsin-like protease and acquires enzymatic activity after removing the pre- and pro-sequences. rTyr p 3 is a 26-kDa protein with equivalent IgE reactivity but weaker enzymatic activity than that of nTyr p 3. A limited level of cross-reactivity has been found between rTyr p 3, Der p 3 and Blomia. Eight of 10 T. putrescentiae-sensitized individuals showed >50% histamine release after triggering with rTyr p 3. Conclusions: Our studies demonstrate that Tyr p 3 is a frequent allergen (58%) in T. putrescentiae-sensitized patients. Since rTyr p 3 displays equivalent biological activities as nTyr p 3, the role of group 3 allergens can be studied using rTyr p 3 to elucidate the pathogenic effects and diagnostic applications of Tyr p 3.
Aedes aegypti (L.) and Aedes albopictus (Skuse) differ in their distribution in Taiwan. The former species is distributed in the south of Taiwan, whereas the latter is found throughout the island. One possible explanation proposes that low temperatures in the winter prevent the expansion of Ae. aegypti. Hence, the impact of low temperatures on immatures of both species was studied in the laboratory and in the field. Our study showed that, under most conditions, Ae. aegypti were more sensitive to low temperatures than Ae. albopictus both in the laboratory and in the field. The survival rates at 10 degrees C for the first and fourth instars of Ae. albopictus were significantly better than those of Ae. aegypti. At 2.5 and 5.0 degrees C, the first instars of Ae. albopictus survived better than the same stadium of Ae. aegypti, but the fourth instars of Ae. aegypti survived better. Short exposures to low temperatures did not affect the acclimatization of Ae. aegypti immatures but longer exposures did increase the physiological adaptation to low temperatures. For Ae. albopictus, exposure to low temperatures increases the acclimatization of this species. In field experiments, Ae. aegypti larvae had a significantly higher mortality than Ae. albopictus during exposures to cold fronts in the 2004 winter. We conclude that low temperatures in northern and central Taiwan have a negative impact on the distribution of Ae. aegypti, but this factor alone is not sufficient to prevent this species from occupying the rest of Taiwan.
Tyrophagus putrescentiae and Dermatophagoides pteronyssinus are causative factors for the development of airway hypersensitivity. The main objective in this study was to identify the cross-reactive allergens between T. putrescentiae and D. pteronyssinus and investigate their sensitization in patients with allergic rhinitis. The prevalence of sensitization to mites was determined by skin prick tests and histamine release assays. Both immunoblot and ELISA inhibition assays were performed by using the recombinant allergens of T. putrescentiae and D. pteronyssinus. The cross-reactive allergens were identified by using IgE-binding inhibition analysis. The correlations of specific IgE between T. putrescentiae and D. pteronyssinus to group 2 and group 3 mite allergens were compared. A total of 117 allergic rhinitis patients, aged between 16 and 40 years old were recruited to be included in this study. The results showed that 70% (82/117) of allergic rhinitis subjects had skin test positive reactions to D. pteronyssinus or T. putrescentiae. Among these mite-sensitive subjects, there were 81 subjects (81/82) sensitive to D. pteronyssinus and 34 subjects (34/82) sensitive to T. putrescentiae. Among the T. putrescentiae hypersensitive subjects, 97% (33/34) were also sensitized to D. pteronyssinus. In the IgE-binding inhibition analysis, 59% (13/22) subjects had IgE-binding activity of T. putrescentiae that was completely absorbed by D. pteronyssinus, especially components with MW at 16 kDa. In ELISA inhibition testing, 69% of IgE-binding was inhibited by rTyr p 2, and 45% inhibited by rTyr p 3. The titers of IgE antibodies to rTyr p 2 and rDer p 2 were well correlated, but not rTyr p 3 and rDer p 3. In conclusion, most T. putrescentiae sensitized subjects were also sensitized to D. pteronyssinus in young adult allergic rhinitis patients. The complete absorption of IgE binding activity by D. pteronyssinus indicates that T. putrescentiae hypersensitivity might be due to the cross-reactivity, not dual-sensitization of D. pteronyssinus and T. putrescentiae. The IgE-binding titers of group 2 allergens were well correlated and the binding activity of Tyr p 2 could be absorbed by Der p 2, suggesting that group 2 allergens are the major cross-reactive allergen of D. pteronyssinus and T. putrescentiae.
Aedes aegypti (L.) and Aedes albopictus (Skuse) differ in their distribution in Taiwan. The former species is distributed in the south of Taiwan, whereas the latter is found throughout the island. One possible explanation proposes that low temperatures in the winter prevent the expansion of Ae. aegypti. Hence, the impact of low temperatures on immatures of both species was studied in the laboratory and in the field. Our study showed that, under most conditions, Ae. aegypti were more sensitive to low temperatures than Ae. albopictus both in the laboratory and in the field. The survival rates at 10 degrees C for the first and fourth instars of Ae. albopictus were significantly better than those of Ae. aegypti. At 2.5 and 5.0 degrees C, the first instars of Ae. albopictus survived better than the same stadium of Ae. aegypti, but the fourth instars of Ae. aegypti survived better. Short exposures to low temperatures did not affect the acclimatization of Ae. aegypti immatures but longer exposures did increase the physiological adaptation to low temperatures. For Ae. albopictus, exposure to low temperatures increases the acclimatization of this species. In field experiments, Ae. aegypti larvae had a significantly higher mortality than Ae. albopictus during exposures to cold fronts in the 2004 winter. We conclude that low temperatures in northern and central Taiwan have a negative impact on the distribution of Ae. aegypti, but this factor alone is not sufficient to prevent this species from occupying the rest of Taiwan.
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