The global integration has brought China closer t the rest of the world, especially after China succeeded in en tering the WTO and was entitled to host the 2008 Olympi Games in Beijing and the 2010 World Exposition in...The global integration has brought China closer t the rest of the world, especially after China succeeded in en tering the WTO and was entitled to host the 2008 Olympi Games in Beijing and the 2010 World Exposition in Shang hai.With the frequent exchanges between China and other countries in recent decades, more and more internationa friends have come to China.Meanwhile, more and mor bilingual sign words appear in the big cities in China so as t facilitate international friends’ stay in China.Therefore, th English translations of sign words are of paramount impor tance to international tourists.展开更多
Reverse genetics was used to study the effect of particular amino acids of infectious bursal disease virus (IBDV) on virulence. Using site-directed mutagenesis, altering of two amino acids in VP2 (Q253H, A284T) and VP...Reverse genetics was used to study the effect of particular amino acids of infectious bursal disease virus (IBDV) on virulence. Using site-directed mutagenesis, altering of two amino acids in VP2 (Q253H, A284T) and VP3 (H783Q, V862M, I921V) in the segment A of a Chinese very virulent IBDV field strain Harbin-1, 4 virus mutants including H253/284, H783/862, H862/921, H921/783 were rescued. To evaluate the characteristics of the recovered viruses in vivo, we inoculated 4-week-old chickens with virus mutants and rescued Harbin- 1 (rHarbin-1), analyzed their bursae for pathological lesions 4 days postinfection. rHarbin-1 and H783/862, H253/284 caused severe bursal lesion, milder lesion for H862/921, mildest for H921/783. However, H253/284 caused the lowest mortality. The results showed that residue at position Q253, A284 of VP2 and V862, I921 of VP3 gene are involved with virulence, but there is difference between VP2 and VP3’s role in virulence. The ability of 862 and 921 to control virulence in VP3 is stronger than 253 and 284.展开更多
文摘The global integration has brought China closer t the rest of the world, especially after China succeeded in en tering the WTO and was entitled to host the 2008 Olympi Games in Beijing and the 2010 World Exposition in Shang hai.With the frequent exchanges between China and other countries in recent decades, more and more internationa friends have come to China.Meanwhile, more and mor bilingual sign words appear in the big cities in China so as t facilitate international friends’ stay in China.Therefore, th English translations of sign words are of paramount impor tance to international tourists.
文摘Reverse genetics was used to study the effect of particular amino acids of infectious bursal disease virus (IBDV) on virulence. Using site-directed mutagenesis, altering of two amino acids in VP2 (Q253H, A284T) and VP3 (H783Q, V862M, I921V) in the segment A of a Chinese very virulent IBDV field strain Harbin-1, 4 virus mutants including H253/284, H783/862, H862/921, H921/783 were rescued. To evaluate the characteristics of the recovered viruses in vivo, we inoculated 4-week-old chickens with virus mutants and rescued Harbin- 1 (rHarbin-1), analyzed their bursae for pathological lesions 4 days postinfection. rHarbin-1 and H783/862, H253/284 caused severe bursal lesion, milder lesion for H862/921, mildest for H921/783. However, H253/284 caused the lowest mortality. The results showed that residue at position Q253, A284 of VP2 and V862, I921 of VP3 gene are involved with virulence, but there is difference between VP2 and VP3’s role in virulence. The ability of 862 and 921 to control virulence in VP3 is stronger than 253 and 284.
