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Background: Respiratory Syncytial Virus (RSV) infection is a significant cause of bronchiolitis and pneumonia, mostly responsible for hospitalization and infant death worldwide. However, in recent years the importance of extrapulmonary RSV manifestations, especially at neurological level, have become evident. Seizures, lethargy, ataxia and status epilepticus are suggestive of brain involvement, but also in their absence a direct neurological damage RSV-related need to be evaluated., Case Presentation: A 40-day old male infant was admitted to the Emergency Department with severe bronchiolitis and dyspnea. The patient was reported to be coughing for a week with a vomiting episode in the previous two days. The nasopharyngeal swab confirmed the diagnosis of RSV infection and blood gas test showed hypoxemia and respiratory acidosis. For these reasons, the patient was provided with oxygen therapy. A few hours later, after an initial improvement in clinical parameters, a worsening of respiratory dynamics occurred and the patient was prepared for endotracheal intubation, but in the meantime death occurred. During all the observation period in the Emergency Room, no signs of neuropathological damage were evident. Post mortem examination showed lungs congestion with alveolar atelectasis and white matter degradation with severe edema at brain level. Microbiological analysis performed on autoptic samples confirmed the presence of RSV genome in tracheobronchial aspirate, meningeal swabs, pericardic and abdominal fluids, lung and brain biopsies., Conclusions: RSV is usually associated with respiratory diseases, however, as reported by an increasingly number of studies, the systemic dissemination of virus during severe disease can lead to a sudden infant death. The clinical picture herein reported showed a severe bronchiolitis resulting in a fatal and underestimated cerebral involvement due to RSV neurotropic behaviour and underline the need for clinicians to pay more attention to neurological involvement of RSV infection, even in absence of cerebral damage evidence., (© 2021. The Author(s).)

ABTRACT: A new potexvirus affecting ornamental allium spp in the Netherlands was identified and characterized at the molecular level. The virus had a single-stranded RNA genome of 7100 bp (excluding the 18 bp poly A tail). The genome organization was found to be typical of members of the genus Potexvirus and consisted of five open reading frames (ORF). Nucleotide and amino acid sequence comparisons with those of known potexvirus members showed that this virus is related to Hosta virus X and Hydrangea ringspot virus. Sequence similarities and phylogenetic relationships suggested that the allium virus is a new and distinct species in the genus Potexvirus and the name, Allium virus X (AlVX) is proposed.

Plants of Triteleia hyacinthina, Triteleia ixioides Starlight, and Triteleia laxa Corina with severe mosaic and yellow vein-banding were found to be infected with a potyvirus. The 3'-terminal region of the virus was amplified by RT-PCR from total RNA using a potyvirus-specific degenerate primer (poty5P: 5' GGN AAY AAY AGY GGN CAR CC 3') and an oligo-dTprimer. The sequence generated included the 3'-NIb protein coding region (680 nucleotides), the entire coat protein coding region (840 nucleotides), and 3'-untranslated region (UTR) (253 nucleotides). Amino acid identity of the whole CP between the triteleia virus and potyvirus member ranged from 54% Apium virus Y (ApVY) to 67% Auraujia mosaic virus (ArjMV) and Twisted-stalk chlorotic streak virus (TSCSV) and the core ranged from 59% (ApVY) to 75% (ArjMV). The 3-UTR showed no significant homology with other known potyviruses. Phylogenetic relationships suggest this triteleia virus is a new member of the Potyvirus genus and the name of "Triteleia mosaic virus" (TriMV) is proposed. This is the first report of a potyvirus infecting triteleia.

A distinct caulimovirus, associated with dahlia mosaic, was cloned and sequenced. The caulimovirus, tentatively designated as dahlia common mosaic virus (DCMV), had a double-stranded DNA genome of ca. 8 kb. The genome organization of DCMV was found to be typical of members of the genus Caulimovirus and consisted of six major open reading frames (ORFs), ORFs I-VI, and one minor ORF, ORF VII. Sequence comparisons with the DNA genomes of two known caulimoviruses isolated from dahlia, Dahlia mosaic virus (DMV) and an endogenous caulimovirus, DMV-D10, showed that DCMV is a member of a distinct caulimovirus species, with sequence identities among various ORFs ranging from 25 to 80%.

A semi-automated, rapid and sensitive method that combines magnetic capture-hybridization and reverse-transcription polymerase chain reaction (MCH/RT-PCR) for the detection of plant viruses is described. The assay uses a target specific biotin-labelled oligoprobe for RNA capture and streptavidin-coated magnetic beads for subsequent RNA-oligoprobe hybrid isolation from plant lysate. Detection and specific identification was accomplished by RT-PCR. This approach was investigated for the specific detection of Tobacco rattle virus and for the detection of viruses within the Potexvirus group in leaves, dormant bulbs and corms of flower bulbs of different species. Dilution series of TRV-infected tulip leaf sap showed that MCH/RT-PCR was 70,588 times more sensitive than enzyme-linked immunosorbent assay (ELISA) and was similar to that of RT-PCR. ELISA underestimated the infection levels of TRV in field samples compared to MCH/RT-PCR. The ability of MCH/RT-PCR to be performed in a microtiter plate on an automatic nucleic acid isolation station facilitates high throughput virus diagnostics. RNA isolation and purification was rapid, specific, sensitive, contamination-free and reproducible making this method amenable for routine indexing of stock plants as part of a management plan to reduce the propagation of virus-infected plants.

Dahlia mosaic, caused by Dahlia mosaic virus (DMV), is one of the most important viral diseases of dahlia. Molecular characterization of DMV showed the association of two distinct caulimoviruses (DMV-D10, DMV-Portland) and a D10-like sequence variant (DMV-Holland) with the disease. Using primers specific to these two viruses and the sequence variant, a polymerase chain reaction-based assay was used to determine their relative incidence in several dahlia samples from the United States and the Netherlands. Testing was done on samples collected in 2005 and 2006 in the United States and in 2006 in the Netherlands. Results indicated the predominance of DMV-D10 over DMV-Portland and DMV-Holland in both the United States and the Netherlands. Using conserved regions of the viral genome, primers were designed and used to detect all three sequences. Results suggested that DMV-D10 is predominantly associated with dahlia mosaic, but diagnostics should also include testing for DMV-Portland and DMV-Holland.

A survey to identify virus diseases affecting Crocus spp. in the Netherlands was conducted during April 2004. Crocus spp. (cvs. Flavus, Pick-wick, Remembrance, and Grand Maitre) with symptoms suggestive of virus infection (stunting, yellowing, necrosis, and flower color breaking) were collected from several fields in the Breezand and Lisse districts in northern and southern Netherlands, respectively. All samples were tested for the presence of six known crocus-infecting viruses (1,2) using enzyme-linked immunosorbent assay (ELISA) and reverse transcription-polymerase chain reaction (RT-PCR) assays. The ELISA assay was performed with the following polyclonal and monoclonal antibodies: Iris severe mosaic virus (ISMV); Tobacco rattle virus (TRV) isolates F, Y, and J obtained from the Applied Plant Research Institute, Lisse, Netherlands; Arabis mosaic virus; Cucumber mosaic virus from the Plant Research International Institute, Wageningen, Netherlands; Iris yellow spot virus (IYSV) from the Virology Department at Wageningen University, Netherlands; and the potyvirus group-specific monoclonal antiserum from the DSMZ, Braunschweig, Germany. All samples that tested positive with a potyvirus antiserum were further tested for the presence of Bean yellow mosaic virus (BYMV) using a BYMV-specific antiserum. Serological results obtained indicated that BYMV, detected with the potyvirus antiserum and BYMV-specific antiserum, and ISMV were the most commonly encountered viruses. Tobacco necrosis virus (TNV) and TRV were only found occasionally, whereas IYSV, was not detected in any of the samples tested. To study the presence of viruses not yet reported, total RNA was extracted and tested with a RT-PCR assay with carlavirus, potexvirus, necrovirus (R. Miglino, unpublished), and potyvirus (3) genus-specific oligonucleotides. In accordance with the ELISA results, PCR amplicons were obtained with the potyvirus, TNV, and TRV primer sets. Furthermore, a 280-bp amplicon corresponding to the expected size was amplified in a RT-PCR assay performed on total RNA with a potexvirus genus-specific primer set. The reverse primer (5'-AGC ATG GCG CCA TCT TGT GAC TG-3') was located upstream in the conserved viral replicaseencoding region at position 4254-4231 of Narcissus mosaic virus (NMV) RNA genome (Genbank Accession No. D13747) and the forward primer (5'-CTG AAG TCA CAA TGG GTG AAG AA-3') was located downstream at position 3969-3992. Sequence homology using BLAST analysis of the cloned and sequenced PCR product showed 98% identity with NMV. Although the virus has a very narrow host range, the results of this study may have a significant impact on the crocus industry in the Netherlands. To our knowledge, this is the first report of NMV infecting crocus. References: (1) M. G. Bellardi and A. Pisi. Inf. Fitopatol. 37:33, 1987. (2) A. F. L. M. Derks. Crocus spp. Pages 260-264 in: Virus and Virus-like Diseases of Bulbs and Flower Crops. G. Loebenstein et al., eds. Wiley publishers, West Sussex, UK, 1995. (3) S. A. Langeveld et al. J. Gen. Virol. 72:1531, 1991.

RNA 3 of alfalfa mosaic virus (AMV) encodes the 5'-proximal movement protein (MP) gene and the 3'-proximal coat protein (CP) gene which is expressed from a subgenomic RNA. Several strategies were explored to use this RNA as a vector for expression of the green fluorescent protein (GFP) in Nicotiana tabaccum plants expressing the viral polymerase proteins P1 and P2 (P12 plants). Insertion of a subgenomic promoter (sgp)-GFP cassette between the CP gene and the 3'-untranslated region (UTR) interfered with RNA accumulation in protoplasts, indicating that cis-acting sequences required for replication were disrupted. When GFP was fused to the N-terminus of MP or CP, the chimeric RNAs accumulated in protoplasts but cell-to-cell movement in plants was blocked. Insertion of a GFP-sgp cassette immediately upstream of the CP gene caused a hypersensitive host response. However, insertion of a GFP-sgp cassette upstream of the MP gene did not affect symptom formation and yielded a vector that expressed GFP in inoculated but not in the systemic leaves of both P12 tobacco and non-transgenic N. benthamina plants. When the size of the GFP gene was reduced from 700 to 300 nucleotides, virus infection was observed in the non-inoculated leaves. Analysis of the progeny of some chimera revealed novel data on replication, encapsidation and recombination of AMV RNA 3.

In contrast to most alfalfa mosaic virus (AMV) strains (YSMV, S, M and 425), AMV strains VRU and 1 5/64 can form abnormally long virus particles, an ability which has been linked to the coat protein (CP). In order to study this phenomenon, the CP-encoding RNAs 3 of AMV strains VRU and 1 5/64 were cloned and fully sequenced. Comparative sequence analyses of AMV RNA 3 sequences derived from different strains revealed two non-conservative amino acid substitutions, Ser65 and Leu175, which occur exclusively in the closely related VRU- and 15/64-CPs. When these amino acid alterations were introduced into the CP of AMV strain 425 unusually long virus particles were assembled. This confirms that amino acids Ser66 and Leu175 of the CPs of AMV strains VRU and 15/64 are involved in the formation of tubular virus particles.