Rapid antigenic evolution in the influenza A virus hemagglutinin precludes effective vaccination with existing vaccines. To understand this phenomenon, we passaged virus in mice immunized with influenza vaccine. Neutralizing antibodies selected mutants with single-amino acid hemagglutinin substitutions that increased virus binding to cell surface glycan receptors. Passaging these high-avidity b...

Specific cytotoxic thymus-derived (T) lymphocytes were detected in the cervical lymph nodes and spleen during influenza infection of mice. The cytotoxic T cells can distinguish target cells infected with different influenza A subtypes. Infection with parent viruses and their recombinant progeny possessing the hemagglutinin of one parent and the neuraminidase of the other demonstrated that sign...

High hemagglutinin titres against chicken erythrocytes were detected in the sera of Trypanosoma congolense-infected sheep. Adsorption of sheep sera with solubilized T. congolense resulted in marked reduction of hemagglutinin titre. Heat inactivation of the sera at 56 degrees C for 30 min had no demonstrable effects on the hemagglutinin titre. Sera collected from the sheep before trypanosome inf...

Filamentous hemagglutinin (FHA), the major 230-kDa adhesin of the whooping cough agent Bordetella pertussis, is one of the most efficiently secreted proteins in Gram-negative bacteria. FHA is secreted by means of the two-partner secretion (TPS) pathway. Several important human, animal, and plant pathogens also secrete adhesins and other virulence factors by using this mode of secretion. A TPS s...

In the present study, 110 fungal strains of Persian Type Culture Collection (PTCC) including some selected strains isolated in various screening projects were tested for their potentiality to produce lovastatin, a competitive inhibitor of 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-CoA reduc-tase), the rate-limiting enzyme of cholesterol biosynthesis. The fungal strains were cultivated in a t...

The genomic segment encoding the putative hemagglutinin of infectious salmon anemia virus (ISAV) is described. Expression of the putative hemagglutinin in a salmon cell line demonstrated hemadsorptive properties of the protein for salmon erythrocytes. The polypeptide was recognized by an ISAV-specific monoclonal antibody. Nucleotide sequencing indicated the occurrence of a variable region in th...

The role of the immune response to measles virus in acute infection or in disease states associated with this virus is of major interest. The viral genome-specified surface antigens of measles, the hemagglutinin and fusion proteins, are likely to be of paramount importance with respect to the host immune response to the virus. This report describes initial studies aimed at assessing the immune ...

Purified type A influenza viral hemagglutinin stimulates an in vitro cell-mediated cytotoxic cell response that exhibits a high degree of specificity for the immunizing hemagglutinin. The response magnitude is proportional to the hemagglutinin dose used for stimulation. The lytic activity of the effector cells is H-2 restricted. Analysis of the specificity of the response indicated that these c...