Influenza A viruses: Current perspectives on swine flu virus

ABSTRACT Interferon-mediated host responses are of great importance for controlling influenza A virus infections. It is well established that the interferon-induced Mx proteins possess powerful antiviral activities toward most influenza viruses. Here we analyzed a range of influenza A virus strains for their sensitivities to murine Mx1 and human MxA proteins and found remarkable differences. Virus strains of avian origin were highly sensitive to Mx1, whereas strains of human origin showed much weaker responses. Artificial reassortments of the viral components in a minireplicon system identified the viral nucleoprotein as the main target structure of Mx1. Interestingly, the recently reconstructed 1918 H1N1 “Spanish flu” virus was much less sensitive than the highly pathogenic avian H5N1 strain A/Vietnam/1203/04 when tested in a minireplicon system. Importantly, the human 1918 virus-based minireplicon system was almost insensitive to inhibition by human MxA, whereas the avian influenza A virus H5N1-derived system was well controlled by MxA. These findings suggest that Mx proteins provide a formidable hurdle that hinders influenza A viruses of avian origin from crossing the species barrier to humans. They further imply that the observed insensitivity of the 1918 virus-based replicon to the antiviral activity of human MxA is a hitherto unrecognized characteristic of the “Spanish flu” virus that may contribute to the high virulence of this unusual pandemic strain.

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The Etiology of Viral Lower Respiratory Tract Infections at a Tertiary Hospital in Jordan over Five Years

The International Arabic Journal of Antimicrobial Agents ◽

10.3823/831 ◽

2019 ◽

Vol 9 (2) ◽

Author(s):

Isam Bsisu ◽

Zaina Obeidat ◽

Nidaa Ababneh ◽

Mai Altous ◽

Mohammed Obeidat ◽

...

Keyword(s):

Respiratory Tract ◽

Real Time ◽

Real Time Pcr ◽

Lower Respiratory Tract ◽

Influenza A ◽

Fast Track ◽

Swine Flu ◽

Pandemic H1n1 ◽

Causative Agents ◽

Flu Virus

Background Lower respiratory tract infection (LRTI) is the most common condition treated in primary care and is considered the third leading cause of death worldwide. The objective of our study is to determine the etiological agents that cause viral LRTI in Jordan, aiming to help physicians to choose the appropriate treatment strategy. Materials and Methods We conducted a retrospective study on patients who were admitted with the diagnosis of LRTI between January, 2011 and January, 2016. We used Fast-track Diagnostics (FTD)® Respiratory 21 Kit (Fast-track Diagnostics, Luxembourg) real-time PCR to determine the viral etiology of LRTI, and we investigated pandemic H1N1 2009 swine flu virus using rapid test PCR. Results This study involved 495 patients with a mean age of 57.79 ± 18.43 years. The causative agents were identified in 157 patients out of 495 patients (31.7%). FTD real-time PCR was done for 170 patients, and the test was positive for seasonal Influenza A virus in 7.1% of patients, influenza B in 4.1%, RSV in 4.7%, metapneumovirus in 4.1%, adenovirus in 4.1%, corona 229E/NL63 in 4.1%, parainfluenza virus in 7.6%, and rhinovirus in 3.5%. The percent of cases who were positive for pandemic H1N1 2009 swine flu virus was 4.2%. The rate of ICU admission was 16.8%, and the mortality rate of LRTI was as low as 3.64%. Conclusions Viral LRTI is more common in winter season in Jordan, especially in January. Remarkably, Influenza A and Parainfluenza viruses were the main viral causative agents for LRTI in our study.

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