Monitoring of pigeon paramyxovirus type-1 in organs of pigeons naturally infected with Salmonella Typhimurium.

&lt;p&gt;An experimental pigeon paramyxovirus (pPMV-1) infection was followed by reverse transcription-nested polymerase chain reaction for 31 days after infection, in 16 organs of inoculated or contact pigeons naturally infected with Salmonella Typhimurium. With two exceptions, both groups presented similar results. Typical nervous signs and a green diarrhoea were observed. The spread of pPMV-1 was relatively quick, all organs being largely positive at 4 days after inoculation or contact. The lung, spleen, caecal tonsils, kidneys and brain, for which almost all tested samples remained positive during most of the experiment, seemed to be the principal targets for virus persistence. However, the virus was significantly recovered later in the brain parts and for longer in the trachea of the contact pigeons than of the inoculated ones.&lt;/p&gt;</p

Molecular study of the quasispecies evolution of a typical pigeon paramyxovirus type 1 after serial passages in pigeons by contact.

&lt;p&gt;The quasispecies nature of a typical pigeon paramyxovirus type 1 (pPMV-1) was, for the first time, studied under conditions close to the natural infectious environment. The virus was serially passaged in pigeons by successive contacts. Viral heterogeneity was analysed in the kidneys and brain of five pigeons from the last contact, by reverse transcriptase-polymerase chain reactions performed on RNA directly extracted from the organ and targeting the P and HN genes of the virus. The viral diversity following in vivo passage was found to be different from that in the inoculum, but demonstrated the reality of the quasispecies concept for pPMV-1 strains. Moreover, some aberrant genomic RNAs comprising insertions in the P gene editing site or deletions in the HN gene were also detected, with possible consequences for the pathogenicity and infectivity of the virus.&lt;/p&gt;</p

Molecular characterisation of three avian paramyxovirus type 1 isolated from pigeons in France.

&lt;p&gt;Three avian Paramyxovirus type 1 (aPMV-1) isolated from pigeons duringpigeon paramyxovirosis outbreaks were molecularly characterised by sequencing parts of the six genes (NP, P, M, F, HN and L) of each strain. Virulent 99143 isolate was found to be very closely related to non-pathogenic vaccine strains of aPMV-1, even for its F protein cleavage site motif. Strains 99299 and 99106, typical pigeon paramyxovirus type 1 (pPMV-1) variants, exhibited between 10% and 20% difference with aPMV-1 at the nucleotide level. The aPMV-1 specific pattern of eight amino acids in the intracellular domain of HN protein was found different by one residue for these two isolates, and might represent a specific pattern for pPMV-1. The unique sequence of the polycistronic P gene editing site of 99299 and 99106 was characterised by four instead of three cytosine residues, and might so have an influence on the expression level of the three proteins encoded by P. This work is also the first to provide molecular data on NP, P and L genes of typical pPMV-1.&lt;/p&gt;</p

Quasispecies nature of an unusual avian paramyxovirus type-1 isolated from pigeons.

&lt;p&gt;An avian paramyxovirus type-1 (APMV-1) was classified as virulent according to its Intra Cerebral Pathogenicity Index (ICPI), but as avirulent according to the motif of its F protein cleavage site. Although this atypical APMV-1 was isolated from sick, unvaccinated pigeons, it was not grouped with pigeon variants regarding its antigenic and genetic characterisation. We analysed its quasispecies nature by cloning and sequencing parts of the genome in three different genes to evaluate if heterogeneity might explain the difference observed between the ICPI and the F protein cleavage site motif. Two distinct sub-populations were detected in the phosphoprotein gene. In the fusion protein gene, two clones were found to be related to typical pigeon variants in the hypervariable domain.&lt;/p&gt;</p

Incorporation of the influenza A virus NA segment into virions does not require cognate non-coding sequences.

&lt;p&gt;For each influenza virus genome segment, the coding sequence is flanked by non-coding (NC) regions comprising shared, conserved sequences and specific, non-conserved sequences. The latter and adjacent parts of the coding sequence are involved in genome packaging, but the precise role of the non-conserved NC sequences is still unclear. The aim of this study is to better understand the role of the non-conserved non-coding sequences in the incorporation of the viral segments into virions. The NA-segment NC sequences were systematically replaced by those of the seven other segments. Recombinant viruses harbouring two segments with identical NC sequences were successfully rescued. Virus growth kinetics and serial passages were performed, and incorporation of the viral segments was tested by real-time RT-PCR. An initial virus growth deficiency correlated to a specific defect in NA segment incorporation. Upon serial passages, growth properties were restored. Sequencing revealed that the replacing 5&amp;#39;NC sequence length drove the type of mutations obtained. With sequences longer than the original, point mutations in the coding region with or without substitutions in the 3&amp;#39;NC region were detected. With shorter sequences, insertions were observed in the 5&amp;#39;NC region. Restoration of viral fitness was linked to restoration of the NA segment incorporation.&lt;/p&gt;</p