Sequence determination and genetic analysis of the leader region of various equine arteritis virus isolates.

The entire leader sequence of ten equine arteritis virus (EAV) isolates including the Bucyrus reference strain was determined and analyzed at the primary nucleotide and secondary structure levels. The leader sequence of eight EAV isolates was determined to be 206 nucleotides (nt) in length, whereas those of the 86AB-A1 and 86NY-A1 isolates were found to be 205 and 207 nt in length, respectively. The sequence identity of the leader sequences between the different isolates and the Bucyrus reference strain ranged from 94.2 to 98.5%. An AUG start codon found at position 14 in all EAV isolates could initiate an open reading frame (ORF) that could produce a polypeptide of 37 amino acids, except for the 86NY-A1 isolate where the intraleader polypeptide would contain 54 amino acids. Five patterns of computer-predicted RNA secondary structures were identified in the ten EAV leader regions analyzed. All EAV isolates showed three conserved stem-loops (designated A, B and C). An additional conserved stem-loop (D) was observed in six EAV isolates, including the Bucyrus reference strain. Based on the presence or absence of stem-loop D, all EAV isolates analyzed in this study could be tentatively classified into two genogroups (I and II). The significance of the intraleader ORF and the predicted secondary structures has yet to be determined.

Nucleotide sequence and genetic analysis of the leader region of Canadian, American and European equine arteritis virus isolates.

The extreme 5' end, the entire leader sequence of the Arvac vaccine strain, and 10 equine arteritis virus (EAV) isolates, including the ATCC Bucyrus reference strain and 5 Canadian field isolates, were determined and compared at the primary nucleotide and secondary structure levels. The leader sequence of eight EAV isolates, including the Bucyrus reference strain, and the leader sequence of the Arvac vaccine strain was determined to be 206 nt in length (not including the putative 5' cap structure-associated nucleotide) whereas those of the 86AB-A1 and 86NY-A1 isolates were found to be 205 and 207 nt in length, respectively. The sequence identity of the leader sequences, between the different isolates and the Bucyrus reference strain, ranged from 94.2 to 98.5%. Phylogenetic analysis and estimation of genetic distances, based on the leader nucleic acid sequences, showed that all EAV isolates/strains are likely to represent a large phylogenetically-related group. An AUG start codon found at position 14 in all EAV isolates/strains could initiate an open reading frame (ORF) that could produce a polypeptide of 37 amino acids, except for the 86NY-A1 isolate where the intraleader polypeptide would contain 54 amino acids. Computer-predicted RNA secondary structures were identified in the 11 EAV leader regions analyzed. All EAV isolates/strains showed 3 conserved stem-loops (designated A, B and C). An additional conserved stem-loop (D) was observed in 7 EAV isolates, including the Bucyrus reference strain. The leader region distal to stem-loop D did not contain conserved sequences or stem-loop structures common to the EAV isolates/strains.

Expression cloning and humoral immune response to the nucleocapsid and membrane proteins of equine arteritis virus.

To provide a convenient and sensitive method for the detection of equine arteritis virus (EAV)-specific serum antibodies, we developed an immunoblot assay employing the EAV nucleocapsid (N) and membrane (M) proteins expressed in a procaryotic expression vector (pMAL-c2) for the production of recombinant maltose-binding (MBP) fusion proteins (MBP-N and MBP-M). The antigenic reactivity of the recombinant fusion proteins and their Xa factor cleavage EAV products was confirmed by immunoblot using horse antisera to EAV. Some horse sera, however, showed immune reactivity to the MBP fusion partner protein. Based on a total of 32 horse sera analyzed for the presence of EAV antibodies by immunoblot, using the MBP-N or -M fusion proteins and the Xa factor cleavage EAV products, and in the serum neutralization test, there was 100% concordance between the assays. Sera from horses experimentally infected with EAV were reactive in the immunoblot test with both the MBP-N and the MBP-M fusion proteins by day 14 after EAV exposure. The reactivity continued to the end of the experiment at day 145 after infection. This immune reactivity correlated with the detection of neutralizing antibodies in the serum samples. Based on these findings, the recombinant N and M proteins might be useful for serodetection of EAV-infected animals.

Sequence determination of the extreme 5' end of equine arteritis virus leader region.

The extreme 5' end of the leader sequence of four equine arteritis virus (EAV) strains was obtained by using rapid amplification of cDNA end method (5' RACE), and sequenced. Seventeen more nucleotides were added upstream of the 5' end of the EAV published genomic sequence. A common feature among the analyzed EAV isolates was the presence of an AUG start codon within the added sequence and the appearance of an intraleader open reading frame (ORF) of 111 nucleotides which was predicted to encode a peptide of 37 amino acids. The role of this putative intraleader ORF has yet to be determined.

The 64 kDa lipoprotein of Mycoplasma gallisepticum has two distinct epitopes responsible for haemagglutination and growth inhibition.

A major Mycoplasma gallisepticum polypeptide of 64 kDa (p64) was characterized using two distinct monoclonal antibodies (MAbs), MAb KI produced in our laboratory and MAb MyG 001 produced by Avakian & Ley (1993). The p64 antigen was shown to be a lipoprotein in a radioimmunoprecipitation assay using [(3)H] palmitic acid-labelled M. gallisepticum cultures. The two MAbs inhibited the growth of M. gallisepticum in liquid medium and reacted to two distinct epitopes on the same p64 antigen in competitive enzyme-linked immunosorbent and chemiluminescence Western immunoblot assays. MAb Kl inhibited haemagglutination of chicken and turkey erythrocytes whereas MAb MyG 001 did not. The results of our study indicate that p64 has two distinct epitopes involved in haemagglutination and growth inhibition of M. gallisepticum. MAb Kl also inhibited the attachment of the mycoplasma to TLT lymphoblastoid chicken B cell line, suggesting that p64 is a cytadhesin.

[Postoperative blindness after buccal tumorectomy and bilateral radical neck dissection]. / Cécité postopératoire après tumorectomie buccale et curage cervical bilatéral.

A case of bilateral blindness in a 47-year-old patient after buccal tumorectomy and bilateral neck dissection is reported. The diagnosis of posterior optic ischaemia was substantiated by the features of blindness and the negativity of cerebral CT-scanography and NMR imaging. The respective roles of atherosclerosis, arterial hypotension, acute anaemia and increased intracranial pressure are discussed. Preventive measures include a strict control of blood pressure, blood loss and head position.

Metabolic radiolabelling of Mycoplasma gallisepticum on Vero cells and radioimmunoprecipitation assay.

A monoclonal antibody (MAb) A2 was produced against a major polypeptide of Mycoplasma gallisepticum with a molecular mass of 64 kDa. MAb A2 reacted in immunoblot at a titre of 10(4.33) and had a titre of 10(4.5) in an enzyme-linked immunosorbent assay. In a radioimmunoprecipitation assay (RIPA) using metabolic [35S]methionine radiolabelling of M. gallisepticum suspension in Vero cell culture, MAb A2 was able to precipitate the 64 kDa protein and another protein of 47 kDa. The present study involving [35S]methionine labelling of M. gallisepticum in Vero cells represents a novel approach for labelling and characterizing the conformation-dependent mycoplasmal antigens in a RIPA system.

[Irreversible bilateral blindness after functional neck dissection. Apropos of a case and a review of the literature]. / Cécité bilatérale irréversible après curage cervical fonctionnel bilatéral. A propos d'un cas et revue de la littérature.

Postoperative blindness due to ischemic optic neuropathy is a rare and dramatic complication. A review of the literature from 1960 until nowadays reveal several physiopathological mechanisms of the blindness. Through the description of their clinic case of a fourty seven years old man showing definitive postoperative blindness after sustaining surgery for epidermoid carcinoma of the mouth floor, the authors suggest as etiology the conjunction of the following factors: brain venous high pressure, head and neck oedema, hypotension and the vascular state of the patient. Special perioperative care taking in account the risk factors is needed to prevent this complication.