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Summary A 16-year-old male Russian blue cat was presented with acute onset of paraparesis of the forelimbs that progressed to tetraparesis. Neurological examination revealed non-ambulatory tetraparesis with decreased postural reactions in all four limbs. Magnetic resonance imaging revealed multifocal nerve root swelling on the right at C6/C7 and C7/T1, while ultrasonography demonstrated swelling of the right brachial plexus. To understand the cause of the nerve swelling, the right musculocutaneous nerve arising from the brachial plexus and the pectoralis muscle were biopsied. Histologically, there was evidence of neurolymphomatosis (neurotropic lymphoma) with Wallerian degeneration and denervation atrophy of myofibres. The neoplastic lymphoid cells expressed CD79a, CD20 and CD56. Based on these findings, a diagnosis of B-cell neurolymphomatosis was made. Expression of CD56, synonymous with neural cell adhesion molecule, is rare in B-cell lymphomas and has not been reported in feline B-cell lymphomas or feline neurolymphomatosis. CD56 expression was suspected to have played an important role in neurotropism of the neoplastic cells in this case.

Porcine teschoviruses (PTVs) belong to the genus Teschovirus within the family Picornaviridae. PTVs are universal contaminants in pig herds in endemic and multi-infection statuses. Previous research has demonstrated PTV antigens and nucleic acid in renal glomeruli and tubular epithelia, suggesting the possibility that PTVs might be shed and transmitted via urine. The study aimed to demonstrate, in the context of pathogenesis, the presence of PTVs in the urine of naturally infected pigs. Viral loads of fluid and tissue samples quantified by an established qRT-PCR showed detection rates of 100% by head and in urine, feces, plasma and nasal swabs, and 38% in kidney. As predicted, PTVs were present in urine at 10(4.02 ± 1.45) copies/100 μl volume, equivalent to 17% of that in plasma. No significant differences were observed between healthy and culled pigs or among the 7 sampled herds. The presence of PTVs in urine was further substantiated by molecular serotyping. In particular, PTV-10 was identified in the urine of 3 piglets from 3 separate herds, consistent with the most prevalent serotype found in this study, and in plasma. The urine mixes with feces to form slurry making it easier for PTV to spread and contaminate the environment.

Bluetongue is a fatal viral disease in ruminants and has serious economic impacts on the livestock industry. Interactions between bluetongue virus (BTV) and immune cells are interesting because of the unique scenarios in each combination of animal species/breed and viral virulence/serotype. This study investigated the immune response in bovine peripheral blood mononuclear cells (PBMC) infected by the BTV2 Taiwan strain. The replication of the virus was limited in monocytes and monocyte-derived macrophages (MDM), and lymphocytes were less permissive. The cytokine mRNA of IL-4 in PBMC was expressed earlier and in greater quantities than that of innate immunity (TNFα, IL-1β) and cell mediated immunity (CMI) (IFNγ), and the IL-4 protein was stably present in the culture medium until 72 h post-infection (hpi). Even in MDM reconstituted with autologous lymphocyte (MDM-Lymphocyte), the IL-4 still had high mRNA expression level. The level of IgE antibody also increased at 24-72 hpi, suggestive of the engagement of type I hypersensitivity in the pathogenesis. The anti-viral activity contained in the culture supernatant was transferrable to recipient infected PBMC from other cows. However, in infected MDM largely free of lymphocytes, mRNA expressions of IL-1β, TNFα and IL-12p40 were normally expressed from 6 to 48 hpi, supporting the notion that IL-4 elaborated by lymphocytes in PBMC mediated the inhibition of both innate immunity and CMI to BTV2. The sum of responses subsequent to the early IL-4 expression likely constitutes part of the unique scenario in the current BTV2-Cow experimental combination biased toward Th2 response.

Porcine teschoviruses (PTVs) belong to the genus Teschovirus within the family Picornaviridae. PTVs are universal contaminants in pig herds in endemic and multi-infection status. To further the understanding of PTV pathogenesis in endemically infected pigs, a set of samples was studied by real time reverse transcription PCR (qRT-PCR) to quantitate viral loads in tissues and by in situ hybridization (ISH) to locate PTV signals in target cells, both targeting the 5'-NTR. cRNA of PTV-1 and PTV-7, in vitro transcribed from cloned fragments of 5'-NTR of 2 viruses, was used to construct standard curves and to run parallel in qRT-PCR, which had detection limits of 10(1) copies/per reaction, with a linearity in between 10(1) and 10(7) copies/per reaction and correlation coefficients of 0.997-0.9988. The qRT-PCR specifically amplified RNA from PTV-1 to -11, while excluding those of Sapelovirus, PEV-9 and PEV-10. Inguinal lymph node (LN) had the highest viral load of all (assuming 100%), followed by ileac LN (89-91%), tonsil (66-68%), ileum (59-60%), spleen (38-40%), and kidney (30-31%), with the least in brain (22.9%) of the inguinal LN. The 22.9% load in brain was higher than that anticipated from a simple fecal-oral-viremia operative model. The results suggested in addition that intranasal infection and retrograding axonal infection from the tonsils were equally operative and significant. ISH revealed PTV signals in a wider variety of tissue cell types than before. PTV signals were noted most impressively in neurons of the cerebral cortex and hippocampus and in the dark zone of the germinal center and adjacent paracortex of regional LN. Multiple operative models indicated that PTVs seemed to have no difficulty invading the brain. The key to whether encephalitis would ensue resided in the animal's immune status and topographic differences of neurons' susceptibilities to PTVs. When common co-infected agents are present, as is typical in the field, PTVs may synergize in causing diseases.

Porcine teschoviruses (PTVs) belong to the genus Teschovirus within the family Picornaviridae. Hitherto, PTVs have had 13 serotypes associated with a variety of clinical diseases. The virulent PTV-1 strains were associated with highly fatal, nonsuppurative encephalomyelitis of pigs (Teschen disease) in the 1930-1950s. Today, less virulent Talfan strains of PTV-1 are more widespread, and PTVs have contaminated swine herds worldwide (endemic or enzootic) together with a variety of common swine pathogens (multi-infection status). The aim of this study was to investigate the extent to which PTVs play a role in causing diseases in the field, under the endemic and multi-infection situation, when most pigs in the herds are infected and immune. Based on the fecal-oral model of pathogenesis, a set of 15 organs were collected from 30 culled post-weanling piglets of 4-8 weeks old. For nested RT-PCR targeted on the 5'-NTR, the PTV detection rate was 96.7% (by heads), confirming the endemic status, and infection was most commonly detected in the intestines (averaged 61%) and lymphoid organs (averaged 59%), followed by visceral organs (averaged 37%) and the CNS (different parts varied from 17 to 47%). The correlation of PTVs detected by nested RT-PCR and a histological lesion were analyzed by Chi-square test showing that in the field situation only non-suppurative encephalitis in the caudal part of the brain (P=0.054) may be marginal significantly attributed to infection by PTVs. By genotyping based on partial VP1 sequences, 5 serotypes, namely PTV-1, -4, -6, -7, and -11, were identified, with some animals having two serotypes co-existed in different organs.

BTV2/KM/2003 and BTV12/PT/2003 are the first identified bluetongue viruses in Taiwan. The prototype virus BTV2/KM/2003 was previously characterized in various respects as low virulent. In the present study, nucleotide sequences of the ten genome segments and their coding regions of the Taiwan strains were determined and analyzed. The two strains had >96.8% nucleotide and >97.9% deduced amino acid identities to each other, except for the VP2 genes. Their genome sequences, except for NS1 and VP2 genes, clustered overall in the Asian lineage, and were closely related to strains from China, India, Indonesia, and Japan. The phylogenetic trees and nucleotide identities of six BTV genes were suggestive of the geographical origin of the bluetongue virus strains analyzed, with a few exceptions. To examine which genes better distinguished strains from different origins (topography), the distribution of and the levels of differences in nucleotide identities were analyzed, revealing that VP3, NS2, and NS3 genes were more suitable for topotyping of BTVs. Analysis of ratios of non-synonymous/synonymous substitutions (dN/dS values) between putative ancestry and their descendant strains suggested that most BTV genes evolved under a negative selection, whereas the VP7 gene evolved under positive selection, and its non-synonymous substitutions accumulated more rapidly in strains from the Mediterranean region.

Bluetongue is an arthropod-borne viral disease affecting domestic and wild ruminants. Taiwan, with the Tropic of Cancer crossing through it, was considered free of bluetongue virus (BTV) before 2001. The goals of this study are to identify the serotype and phylogeny of Taiwan BTV isolates and to understand the serological status and chronology of BTV infection. Analysis of the S10 gene segment revealed that Taiwan BTV isolates are closely related to Chinese strains. Seropositive results were found in 32.7% of the cattle and 8.2% of the goats by head, and 90.7% of the cattle herds and 28.9% of the goat flocks. Anti-BTV antibodies have existed in goat sera since 1989 and in bovine sera since 1993, and over the years, the seropositive rates in rapidly urbanized districts have decreased, most likely due to the loss of vector habitats. Seropositive rates for sheep were variable, due to a small sample size and a small sheep population. Thus far, all natural BTV infections have been subclinical, consistent with experimental sheep inoculation, revealing that the Taiwan isolate is of low virulence.

Industrial swine production is affected by several serious viral diseases, such as pseudorabies, hog cholera, porcine reproductive and respiratory syndrome, which are frequently complicated with the increased incidence of bacterial complications such as Actinobacillus pleuropneumoniae (APP). This clinical observation is suggestive of a virus-bacteria synergism on the pathogenesis. One hypothesis is that viruses induce polymorphonuclear cell (PMNs, primarily neutrophils) dysfunction resulting in defective antibacterial resistance. The purpose of this study was to use the pseudorabies virus (PrV) as a model to explore the possibility of virus-induced PMN dysfunctions in pigs. The goals were to evaluate, in ex vivo settings, the oxidative burst (OB) function of pig PMNs, and to evaluate whether PrV could affect these responses to APP. We found that PrV served as a mild OB stimulant (2-fold) to pig PMNs, which also launched a significant burst to phorbol 12-myristate 13-diacetate (PMA; 61-fold), to non-opsonized, heat-killed and formaldehyde-fixed APP (8-fold), and to normal pig serum-opsonized APP (34-fold). Interestingly, the PMA-induced OB could be reduced 50-70% by preincubating PMNs with PrV, and the critical target was not likely the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase itself. Inactivated PrV was as efficient as viable PrV at exerting the inhibitory effect. On the other hand, PrV exerted a primarily additive effect on APP-induced OB, when the cytotoxic effect of APP on PMNs was avoided. The current finding suggests the possibility that activated PMNs are susceptible to PrV-induced dysfunction, and that the PrV-APP synergism may require upstream stimuli of PMNs to be initiated.

Mouse hepatitis virus (MHV), a coronavirus, causes encephalitis and demyelination in susceptible rodents. Previous investigations have shown that the MHV spike (S) protein is a critical determinant of viral tropism and pathogenicity in mice and rats. To understand the molecular basis of MHV neuropathogenesis, we studied the spike protein gene sequences of several neutralization-resistant variants of the JHM strain of MHV, which were selected with monoclonal antibodies (MAbs) specific for the S protein. We found that variant 2.2-V-1, which was selected with MAb J.2.2 and primarily caused demyelination, had a single point mutation at nucleotide (NT) 3340, as compared to the parental JHM virus, which predominantly caused encephalitis. This site was in the S2 subunit of the S protein. In contrast, variant 7.2-V-1, which was selected with MAb J.7.2 and primarily caused encephalitis, had two point mutations at NT 1766 and 1950, which were in the S1 subunit. Finally, the double mutant 2.2/7.2-V-2, which was selected with both MAbs J.2.2 and J.7.2, and was attenuated with respect to both virulence and the ability to cause demyelination, had a deletion spanning from NT 1523 to 1624 in the S1 and a point mutation at NT 3340 in the S2. We conclude that at least two regions of the S protein contribute to neuropathogenicity of MHV. We have also isolated a partial revertant of 2.2-V-1, which was partially resistant to MAb J.2.2 but retained the same neuropathogenicity as the variant 2.2-V-1. This revertant retained the mutation at NT 3340, but had a second-site mutation at NT 1994, further confirming that NT 3340 contributed to the pathogenic phenotype of MHV. By comparing these results with MHV variants isolated in other laboratories, which had mutations in other sites on the S gene and yet retained the demyelinating ability, we suggest that the ability of JHM viruses to induce demyelination is determined by the interaction of multiple sites on the S gene, rather than the characteristics of a single, unique site. Our study also revealed the possible presence of microheterogeneity of S gene sequence, particularly in the S1 region, in these viruses. The sequence microheterogeneity may also contribute to the differences in their biological properties.

The neurotropic mouse hepatitis viruses (MHV), in particular strain JHM (JHMV or MHV-4), cause experimental central nervous system demyelination that pathologically resembles multiple sclerosis, an important human demyelinating disease. The mechanism of JHMV-induced demyelination remains unclear, though its tropism for oligodendrocytes had led to the belief that JHMV causes demyelination by direct lysis of these myelin-producing cells. However, several studies have also implicated the involvement of immune responses in the demyelinating process. In this communication, we present evidence that generalized immunosuppression with gamma irradiation prevents JHMV-induced demyelination, a finding that was not limited to a particular strain of JHMV or to one strain of mouse. In addition, significant paralytic-demyelinating disease was restored to infected, irradiated mice after the adoptive transfer of nylon wool nonadherent splenic cells and appeared to be restricted by the major histocompatibility complex (MHC). These observations indicate that the principal mechanisms of JHMV-induced demyelination are most likely immunopathological.