One selection pressure shaping sequence evolution is the requirement that a protein fold with sufficient stability to perform its biological functions. We present a conceptual framework that explains how this requirement causes the probability that a particular amino acid mutation is fixed during evolution to depend on its effect on protein stability. We mathematically formalize this framework ...

Background and Aims: Since 1998, Iranian poultry industry has been affected by avian influenza (AI) virus, subtype H9N2. The association of high mortality and case report of H5N1 and H9N2 influenza virus in wild birds in recent years raised the suspicion of a possible new genetic modified AI virus. Methods: Partial nucleotide sequences and deduced amino acid of hemagglutinin (HA) genes of 4 H9...

Background: Botulinum neurotoxin (BoNT) complexes consist of neurotoxin and neurotoxin-associated proteins. Hemagglutinin-33 (HA-33) is a member of BoNT type A (BoNT/A) complex. Considering the protective role of HA-33 in preservation of BoNT/A in gastrointestinal harsh conditions and also its adjuvant role, recombinant production of this protein is favorable. Thus in this study, HA-33 was expr...

Worldwide, influenza affects millions of individuals and has the potential to cause serious illness or even death. The most effective approach prophylaxis is vaccination, but due strain viral mutation changes, seasonal vaccine frequently limited efficiency needs be administered annually. Although they have been employed clinically, more conserved universal antigens like M2 ectodomain (M2e) hema...

Understanding how influenza viruses traverse the mucus and recognize host cells is critical for evaluating their zoonotic potential, prevention treatment of disease. The surface A virus covered with receptor-binding protein hemagglutinin receptor-cleaving enzyme neuraminidase, which jointly control interactions between cell. These proteins are organized in closely spaced trimers tetramers to fa...

The impending influenza virus pandemic requires global vaccination to prevent large-scale mortality and morbidity, but traditional influenza virus vaccine production is too slow for rapid responses. In this study, bacterial system has been developed for expression and purification of properly folded HA1 antigen as a rapid response to emerging pandemic strains. Here, a recombinant H5N1 (A/Indone...

Influenza viruses possess at their surface two glycoproteins, the hemagglutinin and the neuraminidase, of which the antagonistic functions have to be well balanced for the virus to grow efficiently. Ferraris et al. isolated in 2003-2004 viruses lacking both a NA gene and protein (H3NA- viruses) (Ferraris O., 2006, Vaccine, 24(44-46):6656-9). In this study we showed that the hemagglutinins of tw...

Immune precipitation of 181 sera from 152 patients with natural measles was studied to determine the temporal course and frequency of antibody responses to nucleocapsid, fusion, hemagglutinin, and matrix proteins of measles virus. Large amounts of antibody to nucleocapsid protein developed in all patients by day one of the rash. Antibody to hemagglutinin and fusion proteins developed in all pat...

The genes coding for the surface glycoproteins hemagglutinin-neuraminidase (HN) of the peste des petits ruminants virus (PPRV) and hemagglutinin (H) of rinderpest virus (RPV) were cloned in a cytomagalovirus promoter driven expression vector and expressed transiently in mammalian cells. The protein expression was apparent 24 h after transfection and the expressed proteins were detected at the c...

This study examined the phylogenetic relationship of strains of canine distemper virus (CDV) collected from Paraná State, Brazil, based on the hemagglutinin gene. Urine samples were collected from 4 dogs from northern Paraná State that demonstrated clinical manifestations of canine distemper. The participation of CDV was initially confirmed by RT-PCR targeting the nucleocapsid protein, after wh...