Angiostrongylus vasorum has been recognised as a cause of respiratory and circulatory distress among dogs in southwestern France for more than a decade, and the nematode now appears to be of increasing importance in the British Isles and Denmark. The aim of this review is to give a concise account of present knowledge of this intriguing parasitosis.
A new recombinant factor VIII (FVIII), N8, has been produced in Chinese hamster ovary (CHO) cells. The molecule consists of a heavy chain of 88 kDa including a 21 amino acid residue truncated B-domain and a light chain of 79 kDa. The two chains are held together by non-covalent interactions. The four-step purification includes capture, affinity purification using a monoclonal recombinant antibody, anion exchange chromatography and gel filtration. The specific clotting activity of N8 was 8800-9800 IU mg(-1). Sequence and mass spectrometry analysis revealed two variants of the light chain, corresponding to two alternative N-terminal sequences also known from plasma FVIII. Two variants of the heavy chain are present in the purified product, namely with and without the B-domain linker attached. This linker is removed upon thrombin activation of N8 rendering an activated FVIII (FVIIIa) molecule similar to plasma FVIIIa. All six known tyrosine sulphations of FVIII were confirmed in N8. Two N-linked glycosylations are present in the A3 and C1 domain of the light chain and two in the A1 domain of the heavy chain. The majority of the N-linked glycans are sialylated bi-antennary structures. An O-glycosylation site is present in the B-domain linker region. This site was glycosylated with a doubly sialylated GalNAc-Gal structure in approximately 65% of the product. In conclusion, the present data show that N8 is a pure and well-characterized FVIII product with biochemical properties that equal other FVIII products.
To characterize the variability of recent field isolates of canine distemper virus (CDV) from different hosts and geographical areas, we conducted nucleotide sequence analysis of the gene encoding the haemagglutinin (H), the attachment protein of this virus. Pronounced differences between field isolates were revealed in comparison to the Convac and Onderstepoort vaccine strains. The diversity of CDV appeared to exceed that determined for measles virus. Phylogenetic analysis also separated the field isolates of CDV from the vaccine strains and provided evidence for the existence of different contemporary genotypes of CDV. Isolates from a Greenlandic sledge dog and a Siberian seal formed a distinct lineage. The remaining isolates formed a group. This group contained two European isolates from mink and ferret, a single lineage comprising three European dog isolates, and another separate lineage of North American isolates from dog, javelina, raccoon and captive leopards.Canine distemper virus (CDV) is a highly contagious viral pathogen which can cause lethal systemic disease in dogs and other carnivores. CDV belongs to the genus Morbillivirus
Common frogs (Rana temporaria) were exposed either to third-stage larvae (L3) or to first-stage larvae (L1) of Angiostrongylus vasorum. Following exposure to L3, viable larvae could be detected in the frogs for at least 2 weeks. Following exposure to L1, the frogs developed viable L3 in their tissues within 30 days. In a test of the infectivity of these larvae, one fox was fed frogs previously infected with L3 and another fox was fed frogs previously infected with L1. On autopsy it was found that adult A. vasorum populations had been established in both foxes. Thus, it could be concluded that frogs can act not only as paratenic hosts but also as intermediate hosts for A. vasorum.
N-glycosylation is normally a cotranslational process that occurs during translocation of the nascent protein to the endoplasmic reticulum. In the present study, however, we demonstrate posttranslational N-glycosylation of recombinant human coagulation factor VII (FVII) in CHO-K1 and 293A cells. Human FVII has two N-glycosylation sites (N145 and N322). Pulse-chase labeled intracellular FVII migrated as two bands corresponding to FVII with one and two N-glycans, respectively. N-glycosidase treatment converted both of these band into a single band, which comigrated with mutated FVII without N-glycans. Immediately after pulse, most labeled intracellular FVII had one N-glycan, but during a 1-h chase, the vast majority was processed into FVII with two N-glycans, demonstrating posttranslational N-glycosylation of FVII. Pulse-chase analysis of N-glycosylation site knockout mutants demonstrated cotranslational glycosylation of N145 but primarily or exclusively posttranslational glycosylation of N322. The posttranslational N-glycosylation appeared to take place in the same time frame as the folding of nascent FVII into a secretion-competent conformation, indicating a link between the two processes. We propose that the cotranslational conformation(s) of FVII are unfavorable for glycosylation at N332, whereas a more favorable conformation is obtained during the posttranslational folding. This is the first documentation of posttranslational N-glycosylation of a non-modified protein in mammalian cells with an intact N-glycosylation machinery. Thus, the present study demonstrates that posttranslational N-glycosylation can be a part of the normal processing of glycoproteins.
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