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Amino acid substitutions in the neuraminidase protein of an H9N2 avian influenza virus affect its airborne transmission in chickens.

Lv J, Wei L, Yang Y, Wang B, Liang W, Gao Y, Xia X, Gao L, Cai Y, Hou P, Yang H, Wang A, Huang R, Gao J, Chai T - Vet. Res. (2015)

Bottom Line: Cases of H9N2 avian influenza virus (AIV) in poultry are increasing throughout many Eurasian countries, and co-infections with other pathogens have resulted in high morbidity and mortality in poultry.In this study, we used specific-pathogen-free chickens housed in isolators to investigate the airborne transmissibility of five recombinant H9N2 AIV rescued by reverse genetic technology.The results show that airborne transmission of A/Chicken/Shandong/01/2008 (SD01) virus was related to the neuraminidase (NA) gene, and four amino acid mutations (D368E, S370L, E313K and G381D) within the head region of the SD01 NA, reduced virus replication in the respiratory tract of chickens, reduced virus NA activity, and resulted in a loss of airborne transmission ability in chickens.

View Article: PubMed Central - PubMed

Affiliation: College of Animal Science and Veterinary Medicine, Shandong Agricultural University; Sino-German Cooperative Research Centre for Zoonosis of Animal Origin Shandong Province; Key Laboratory of Animal Biotechnology and Disease Control and Prevention of Shandong Province, Shandong Agricultural University, Daizong Street 61, Taian, 271018, China. ljing20021812@163.com.

ABSTRACT
Cases of H9N2 avian influenza virus (AIV) in poultry are increasing throughout many Eurasian countries, and co-infections with other pathogens have resulted in high morbidity and mortality in poultry. Few studies have investigated the genetic factors of virus airborne transmission which determine the scope of this epidemic. In this study, we used specific-pathogen-free chickens housed in isolators to investigate the airborne transmissibility of five recombinant H9N2 AIV rescued by reverse genetic technology. The results show that airborne transmission of A/Chicken/Shandong/01/2008 (SD01) virus was related to the neuraminidase (NA) gene, and four amino acid mutations (D368E, S370L, E313K and G381D) within the head region of the SD01 NA, reduced virus replication in the respiratory tract of chickens, reduced virus NA activity, and resulted in a loss of airborne transmission ability in chickens. Similarly, reverse mutations of these four amino acids in the NA protein of r01/NASS virus, conferred an airborne transmission ability to the recombinant virus. We conclude that these four NA residues may be significant genetic markers for evaluating potential disease outbreak of H9N2 AIV, and propose that immediate attention should be paid to the airborne transmission of this virus.

No MeSH data available.


Related in: MedlinePlus

Virus titers of airborne H9N2 AIV in an isolator. Air samples were collected simultaneously from the space of two isolators using an AGI-30 liquid sampler operated continuously for an optimized time of 30 min at an airflow rate of 12.5 L/min. Virus titer in the air was expressed as values of EID50/L air. Each color bar represented the every recombinant virus concentration in the air collected every two days from the beginning of 2 dpi in an independent experiment. No airborne virus was detected in the experiment for r01/NASS and r01/NA381 viruses.
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Fig3: Virus titers of airborne H9N2 AIV in an isolator. Air samples were collected simultaneously from the space of two isolators using an AGI-30 liquid sampler operated continuously for an optimized time of 30 min at an airflow rate of 12.5 L/min. Virus titer in the air was expressed as values of EID50/L air. Each color bar represented the every recombinant virus concentration in the air collected every two days from the beginning of 2 dpi in an independent experiment. No airborne virus was detected in the experiment for r01/NASS and r01/NA381 viruses.

Mentions: As shown in Table 2, virus was detected in the oropharyngeal and cloacal swab samples of all rSD01 and r01/NASS inoculated chickens at 4 dpi. rSD01 and r01/NASS virus were also detected in direct contact chickens at 2–14 dpi or 4–10 dpi. rSD01 virus was detected in the oropharyngeal and cloacal swab samples of six aerosol contact chickens at 4 dpi, and ten chickens at 8 dpi. No virus was detected in aerosol contact chickens for r01/NASS. Seroconversion was observed for all inoculated chickens, with average antibody titers increasing until 21 dpi (Figures 2A and B). Seroconversion was also observed for rSD01 infected direct contact chickens and for aerosol contact chickens (Figure 2A). In contrast, seroconversion was not observed for aerosol contact chickens exposed to r01/NASS (Figure 2B). Virus aerosols were detected in the air of rSD01 isolators from 4–10 dpi, but not for r01/NASS isolators (Figure 3). These results indicate that recombinant virus rSD01 was detected in the air and transmitted by aerosols between chickens, but recombinant virus r01/NASS, in which the NA of virus SD01 was replaced by that of virus SS94, was not detected in the air and was not aerially transmitted. These results suggest that the NA gene is an important determinant in virus transmission by aerosols.Table 2


Amino acid substitutions in the neuraminidase protein of an H9N2 avian influenza virus affect its airborne transmission in chickens.

Lv J, Wei L, Yang Y, Wang B, Liang W, Gao Y, Xia X, Gao L, Cai Y, Hou P, Yang H, Wang A, Huang R, Gao J, Chai T - Vet. Res. (2015)

Virus titers of airborne H9N2 AIV in an isolator. Air samples were collected simultaneously from the space of two isolators using an AGI-30 liquid sampler operated continuously for an optimized time of 30 min at an airflow rate of 12.5 L/min. Virus titer in the air was expressed as values of EID50/L air. Each color bar represented the every recombinant virus concentration in the air collected every two days from the beginning of 2 dpi in an independent experiment. No airborne virus was detected in the experiment for r01/NASS and r01/NA381 viruses.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4404070&req=5

Fig3: Virus titers of airborne H9N2 AIV in an isolator. Air samples were collected simultaneously from the space of two isolators using an AGI-30 liquid sampler operated continuously for an optimized time of 30 min at an airflow rate of 12.5 L/min. Virus titer in the air was expressed as values of EID50/L air. Each color bar represented the every recombinant virus concentration in the air collected every two days from the beginning of 2 dpi in an independent experiment. No airborne virus was detected in the experiment for r01/NASS and r01/NA381 viruses.
Mentions: As shown in Table 2, virus was detected in the oropharyngeal and cloacal swab samples of all rSD01 and r01/NASS inoculated chickens at 4 dpi. rSD01 and r01/NASS virus were also detected in direct contact chickens at 2–14 dpi or 4–10 dpi. rSD01 virus was detected in the oropharyngeal and cloacal swab samples of six aerosol contact chickens at 4 dpi, and ten chickens at 8 dpi. No virus was detected in aerosol contact chickens for r01/NASS. Seroconversion was observed for all inoculated chickens, with average antibody titers increasing until 21 dpi (Figures 2A and B). Seroconversion was also observed for rSD01 infected direct contact chickens and for aerosol contact chickens (Figure 2A). In contrast, seroconversion was not observed for aerosol contact chickens exposed to r01/NASS (Figure 2B). Virus aerosols were detected in the air of rSD01 isolators from 4–10 dpi, but not for r01/NASS isolators (Figure 3). These results indicate that recombinant virus rSD01 was detected in the air and transmitted by aerosols between chickens, but recombinant virus r01/NASS, in which the NA of virus SD01 was replaced by that of virus SS94, was not detected in the air and was not aerially transmitted. These results suggest that the NA gene is an important determinant in virus transmission by aerosols.Table 2

Bottom Line: Cases of H9N2 avian influenza virus (AIV) in poultry are increasing throughout many Eurasian countries, and co-infections with other pathogens have resulted in high morbidity and mortality in poultry.In this study, we used specific-pathogen-free chickens housed in isolators to investigate the airborne transmissibility of five recombinant H9N2 AIV rescued by reverse genetic technology.The results show that airborne transmission of A/Chicken/Shandong/01/2008 (SD01) virus was related to the neuraminidase (NA) gene, and four amino acid mutations (D368E, S370L, E313K and G381D) within the head region of the SD01 NA, reduced virus replication in the respiratory tract of chickens, reduced virus NA activity, and resulted in a loss of airborne transmission ability in chickens.

View Article: PubMed Central - PubMed

Affiliation: College of Animal Science and Veterinary Medicine, Shandong Agricultural University; Sino-German Cooperative Research Centre for Zoonosis of Animal Origin Shandong Province; Key Laboratory of Animal Biotechnology and Disease Control and Prevention of Shandong Province, Shandong Agricultural University, Daizong Street 61, Taian, 271018, China. ljing20021812@163.com.

ABSTRACT
Cases of H9N2 avian influenza virus (AIV) in poultry are increasing throughout many Eurasian countries, and co-infections with other pathogens have resulted in high morbidity and mortality in poultry. Few studies have investigated the genetic factors of virus airborne transmission which determine the scope of this epidemic. In this study, we used specific-pathogen-free chickens housed in isolators to investigate the airborne transmissibility of five recombinant H9N2 AIV rescued by reverse genetic technology. The results show that airborne transmission of A/Chicken/Shandong/01/2008 (SD01) virus was related to the neuraminidase (NA) gene, and four amino acid mutations (D368E, S370L, E313K and G381D) within the head region of the SD01 NA, reduced virus replication in the respiratory tract of chickens, reduced virus NA activity, and resulted in a loss of airborne transmission ability in chickens. Similarly, reverse mutations of these four amino acids in the NA protein of r01/NASS virus, conferred an airborne transmission ability to the recombinant virus. We conclude that these four NA residues may be significant genetic markers for evaluating potential disease outbreak of H9N2 AIV, and propose that immediate attention should be paid to the airborne transmission of this virus.

No MeSH data available.


Related in: MedlinePlus