RESUMO
Israel acute paralysis virus (IAPV) is associated with colony collapse disorder of honey bees. Nonetheless, its role in the pathogenesis of the disorder and its geographic distribution are unclear. Here, we report phylogenetic analysis of IAPV obtained from bees in the United States, Canada, Australia, and Israel and the establishment of diagnostic real-time PCR assays for IAPV detection. Our data indicate the existence of at least three distinct IAPV lineages, two of them circulating in the United States. Analysis of representatives from each proposed lineage suggested the possibility of recombination events and revealed differences in coding sequences that may have implications for virulence.
Assuntos
Abelhas/virologia , Demografia , Filogenia , Picornaviridae/genética , Picornaviridae/fisiologia , Animais , Austrália , Sequência de Bases , Análise por Conglomerados , Primers do DNA/genética , Israel , Dados de Sequência Molecular , América do Norte , Alinhamento de Sequência , Análise de Sequência de DNA , Especificidade da EspécieAssuntos
Bacillus cereus/enzimologia , Mycoplasma/citologia , Penicilinase , Soroalbumina Bovina , Acholeplasma laidlawii/citologia , Animais , Anticorpos , Reações Antígeno-Anticorpo , Bovinos , Membrana Celular/efeitos dos fármacos , Detergentes , Estabilidade de Medicamentos , Temperatura Alta , Iodo , Lipídeos , Substâncias Macromoleculares , Membranas Artificiais , Meticilina , Mycoplasma/efeitos dos fármacos , Mycoplasma/crescimento & desenvolvimento , Mycoplasma/metabolismo , Ácidos Oleicos/metabolismo , Sulfatos , Trítio , Vibração , Inibidores de beta-LactamasesRESUMO
Cefoxitin, a poor substrate of the RTEM beta-lactamase (penicillin amido-beta-lactam hydrolase, EC 3.5.2.6), induces a reversible change in the conformation of the enzyme. The change is manifested in gradual loss of catalytic activity and increased susceptibility to proteolytic inactivation. It is prevented by antibodies, which stabilize the native conformation. By contrast, divalent cations, which have no effect on the native enzyme, delay recovery from the cefoxitin-induced state, presumably by reacting with sites made accessible in the partly unfolded enzyme. Prolonged exposure to excess of cefoxitin causes a similar delay. The kinetic evidence, namely, the initial burst of consumption of cefoxitin and the subsequent gradual recovery of activity with better substrates, appears to be consistent with acylation of the active site by cefoxitin followed by a slower deacylation step [Fisher et al. (1980) Biochemistry 19, 2895-2901]. However, additional evidence leads us to conclude that the kinetics observed reflect deformation of the active site, rather than its blockage, by cefoxitin. Of most significance is the transient change in specificity, i. e. a preferential interaction of the recovering enzyme with substrates which are closest in structure to cefoxitin.