MicroRNAs (miRNAs) are small noncoding RNAs of 18–25 nucleotides (nt) in length that represent key regulators of many normal cellular functions through the inhibition of mRNA translation and mRNA degradation.  To date, over 2 500 mature miRNAs have been identified in plants, animals and several types of viruses.  Influenza A virus (IAV), which is a negative-sense, single-stranded RNA virus, does not encode viral miRNA.  However, IAV infection can alter the expression of host miRNAs, either in cell culture or in host.  In turn, host miRNAs regulate IAV life cycle through directly binding to IAV genome or indirectly targeting host factors associated with viral replication.  In this review, we briefly summarized the role and significance of miRNA in relation to IAV pathogenesis.  Understanding the role of cellular miRNAs during viral infection may be beneficial to the identification of novel therapeutic strategies to block IAV replication.

 

Hepatitis-hydropericardium syndrome (HHS) is an infectious disease caused by fowl adenovirus serotype 4 (FAdV-4).  Several structural and non-structural proteins of FAdV-4 have been expressed in Escherichia coli and baculovirus expression system to develop candidate subunit vaccines.  However, the protective efficiency of baculovirus-expressed penton base protein has not been assessed.  In this study, two recombinant capsid proteins, penton base and fiber-2, were constructed.  And then, penton base and fiber-2 were administrated alone or together to specific pathogen-free (SPF) chickens at 14 days of life and boosted at 28 days of life.  At 42 days of life, the immunized groups and the control group were challenged with FAdV-4 virulent strain.  Results show that inoculating penton base or penton base+fiber-2 provided 100% protection to the chickens.  All groups vaccinated with the recombinant protein produced detectable antibodies and showed no apparent lesions.  Thus, baculovirus-expressed penton base protein is a promising candidate subunit vaccine.