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myfinalway

木虫 (正式写手)

应助: 6 (幼儿园)
金币: 1581.4
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帖子: 998
在线: 686.3小时
虫号: 775366
注册: 2009-05-20
性别: GG
专业: 兽医免疫学

[交流] 诚心求助疫苗翻译（本人金币不足，可以后面补上或者其他帮助作为感谢）

本人金币不够，但可以以后补上，管理员可以监督。也可以用其他帮助作为感谢。希望好心人不吝帮助，万分感激！！！！！
One limitation in the use of regular vaccines against AIV or
NDV is that vaccinated poultry frequently cannot be differentiated
from naturally infected birds, making serological surveillance dif-
ficult to perform. However, vaccination of birds with a bivalent
vaccine like rNDV_F3aa-chimericH7, which induces an immune
response against H7 HA and NDV in chickens, makes serological
surveillance against avian influenza possible because vaccinated
animals lack immune responses against antigens present in whole
influenza. Therefore, our bivalent vaccine would be suitable for use
as a ‘‘differentiating infected from vaccinated animals’’ (DIVA)
vaccine. NDV vaccines based on lentogenic strains of NDV are
widely used in poultry. A chimeric NDV_AIV bivalent vaccine
would be administered in the same way as the conventional NDV
vaccines, but would confer protection against both NDV and AIV.

Velogenic NDV strains are able to spread efficiently to neighboring
cells upon infection of a variety of cells in the absence of
exogenous proteases. This property is partially mediated by the F
protein of the virus. The F protein of NDV is synthesized as an
inactive precursor (F0) that needs to be cleaved into a heterodimer
(F1–F2) to be functional. Cleavage of the F protein is mediated by
a host protease that recognizes a cleavage site between the F1 and
F2 subunits. When the F1–F2 heterodimer is expressed on the
surface of infected cells, it induces fusion between the infected cell
and the neighboring cells, resulting in the formation of syncytia.
Because the induction of syncytia helps the spread of the virus from
cell to cell, the use of a vaccine with a velogenic NDV-derived F
cleavage site in poultry may raise potential safety concerns. However,
when we introduced a multibasic cleavage site in the F protein
of the highly attenuated rNDV_B1, the resulting viruses did not
acquire the characteristics typical of velogenic strains with MDTs of
_60 hr in chicken embryos.

We postulated that enhanced incorporation of the H7 HA
protein into rNDV virions may afford a better humoral immune
response, resulting in higher levels of protection in chickens against
highly pathogenic AIV. However, it was previously observed that
virion incorporation of an influenza virus WSN HA protein
expressed from rNDV was lower than the homologous HA protein
expressed from influenza virus (21). If the H7 HA protein contained
the cytoplasmic tail and transmembrane domains of the
NDV envelope glycoprotein (F), which are required for efficient
viral assembly, in place of its own, this resulted in enhanced
incorporation of HA into the viral particle and in improved
immunogenicity of the virus. Indeed, the use of an improved NDV
vector that had enhanced cell-to-cell transmission and allowed for
efficient incorporation of the avian HA into virus particles resulted
in 90% protection against challenge with type A HPAI strains and
complete protection against velogenic NDV.

In summary, the use of reverse genetics systems for the construction
of chimeric influenza or NDV viruses provides a practical
strategy for the protection of poultry against existing and newly
emerging viruses of HPAI, as well as against NDV. It is expected
that these approaches will also prove useful in the development of
bivalent vaccines for other pathogens.

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