[Infectious diseases; virus diseases].
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Communicable Diseases↗
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[Pathology of the cytomegaly; inclusion body disease, virus disease of the salivary glands].
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Humans↗
Identification of alternative splicing and negative splicing activity of a nonsegmented negative-strand RNA virus, Borna disease virus.
Borna disease virus (BDV) is a nonsegmented negative-strand RNA virus that belongs to the Mononegavirales. Unlike other animal viruses of this order, BDV replicates and transcribes in the nucleus of infected cells. Previous studies have shown that BDV uses RNA splicing machinery for its mRNA expression. In the present study, we identified spliced RNAs that use an alternative 3' splice site, SA3, in BDV-infected cell lines as well as infected animal brain cells. Transient transfection analysis of cDNA clones of BDV RNA revealed that although SA3 is a favorable splice site in mammalian cells, utilization of SA3 is negatively regulated in infected cells. This negative splicing activity of the SA3 site is regulated by a putative cis-acting region, the exon splicing suppressor (ESS), within the polymerase exon of BDV. The BDV ESS contains similar motifs to other known ESSs present in viral and cellular genes. Furthermore, our results indicated that a functional polyadenylation signal just upstream of the BDV ESS is also involved in the regulation of alternative splicing of BDV. These observations represent the first documentation of complex RNA splicing in animal RNA viruses and also provide new insight into the mechanism of regulation of alternative splicing in animal viruses.
Alternative Splicing↗
Interaction between infectious bursal disease virus and Newcastle disease virus in chickens.
The Australian strain of infectious bursal disease virus (IBDV), 002/73, affected the response of chickens to Newcastle disease virus (NDV). The titre of serum antibodies to NDV in chickens infected with IBDV was significantly lower than that of birds infected with NDV alone. It also appeared that IBDV affected NDV excretion from chickens as NDV was more frequently isolated from chickens infected with IBDV, IBDV infection did not alter the pathogenicity of NDV in chickens. This Australian strain of IBDV therefore appeared to be immunodepressive in one-day-old chickens.
Animals↗
The in vivo and in vitro effects of chicken interferon alpha on infectious bursal disease virus and Newcastle disease virus infection.
The in vitro and in vivo effects of chicken interferon alpha on infectious bursal disease virus (IBDV) infection were investigated in this study. A cDNA of interferon alpha was first cloned from a Chinese strain chicken Shiqi by reverse transcription-polymerase chain reaction. The deduced amino acid sequence has one amino acid substitution with chicken interferon alpha 1 at residue 65 (N to S) and two amino acid substitutions with chicken interferon alpha 2 at residues 50 (N to S) and 58 (P to L), respectively. A prokaryotic expression system was employed to produce a large quantity of recombinant protein. Recombinant interferon was purified in a one-step process, and an optimal refolding process was devised. About 51% recombinant protein from inclusion bodies was refolded, and the final yield of the recombinant interferon reached 24.66 mg/liter culture. The recombinant interferon suppressed IBDV plaque formation in a dose-dependent manner and ameliorated IBDV and Newcastle disease virus infection in both specific-pathogen-free (SPF) and commercial chickens. The antiviral effect of interferon alpha is more significant in commercial chickens than in SPF chickens, and the route of administration affects the efficacy of interferon therapy. This is the first reported study of the effects of interferon alpha on IBDV infection.
Amino Acid Sequence↗
Serological status for Chlamydophila psittaci, Newcastle disease virus, avian polyoma virus, and Pacheco disease virus in scarlet macaws (Ara macao) kept in captivity in Costa Rica.
From 1998 to 1999, a total of 128 blood samples were collected from scarlet macaws (Ara macao), kept in captivity in 11 different aviaries located in six provinces of Costa Rica. The sera were examined for antibodies directed against Chlamydophila psittaci, Newcastle disease virus (NDV), avian polyoma virus (APV), and Pacheco disease virus (PDV). Testing by enzyme-linked immunosorbent assay (ELISA), showed 16 (12.39%) of the samples (n = 129) exhibited antibodies directed against C. psittaci. Employing haemagglutination inhibition tests for NDV antibodies, all of the samples were found to be negative. The prevalence of antibodies specific for APV was tested with a blocking ELISA and serum neutralization tests (SNT) and 12 of 128 samples (9.37%) were found to be positive with both tests. In SNT, two out of 128 samples (1.56%) were positive for PDV. This is the first description of the serological status in scarlet macaws in captivity in Costa Rica. The study demonstrates the absence of NDV antibodies in the birds investigated on one hand, but also indicates a health hazard for numerous avian species due to the risk of infections with C. psittaci, APV or PDV.
Animals↗
Comparison of two aquatic alphaviruses, salmon pancreas disease virus and sleeping disease virus, by using genome sequence analysis, monoclonal reactivity, and cross-infection.
Cell culture isolates of salmon pancreas disease virus (SPDV) of farmed Atlantic salmon and sleeping disease virus (SDV) of rainbow trout were compared. Excluding the poly(A) tracts, the genomic nucleotide sequences of SPDV and SDV RNAs include 11,919 and 11,900 nucleotides, respectively. Phylogenetic analysis places SPDV and SDV between the New World viruses of Venezuelan equine encephalitis virus and Eastern equine encephalitis virus and the Old World viruses of Aura virus and Sindbis virus. When compared to each other, SPDV and SDV show 91.1% nucleotide sequence identity over their complete genomes, with 95 and 93.6% amino acid identities over their nonstructural and structural proteins, respectively. Notable differences between the two viruses include a 24-nucleotide insertion in the C terminus of nsP3 protein of SPDV and amino acid sequence variation at the C termini of the capsid and E1 proteins. Experimental infections of Atlantic salmon and rainbow trout with SPDV and SDV confirmed that the disease lesions induced by SPDV and SDV were similar in nature. Although infections with SPDV and SDV produced similar levels of histopathology in rainbow trout, SDV induced significantly less severe lesions in salmon than did SPDV. Virus neutralization tests performed with sera from experimentally infected salmon indicated that SPDV and SDV belonged to the same serotype; however, antigenic variation was detected among SDV and geographically different SPDV isolates by using monoclonal antibodies. Although SPDV and SDV exhibit minor biological differences, we conclude on the basis of the close genetic similarity that SPDV and SDV are closely related isolates of the same virus species for which the name Salmonid alphavirus is proposed.
Alphavirus↗
Antibody detection in matched chicken sera and egg-yolk samples by commercial enzyme-linked immunosorbent assay kits for Newcastle disease virus, infectious bronchitis virus, infectious bursal disease virus, and avian reovirus.
ELISA kits have been used to detect antibody in egg yolk. The major advantage eggs offer over blood samples is the ability to collect samples without compromising flock biosecurity. A disadvantage to using egg yolk over sera concerns the method of preparing yolk for antibody testing. The technique used in this study involved a simple dilution method with no mixing or extraction. To determine the adequacy of yolk samples to replace serum samples, a serum sample and the first six eggs were obtained from each of 50 commercial leghorn hens. Mean titers were consistently larger for serum than for yolk, but the size of the difference varied with the virus. The variation of mean egg titer was comparable to that of the serum titer. Correlations between a hen's serum titer and the mean titer from hen eggs were only moderate, ranging from 0.35 to 0.85 across viruses and systems. The ability to predict the serum titer of a single hen by the mean titer from hen eggs may be inadequate.
Animals↗
Virus-like particles in bovine turbinate cells infected with bovine virus diarrhoea/mucosal disease virus.
Thin sections of bovine turbinate cells grown in culture and infected with the NADL strain of bovine virus diarrhoea/mucosal disease virus have been examined by electron microscopy. Infected cells exhibited ultrastructural modification of the rough endoplasmic reticulum and associated with this small numbers of virus-like particles were observed. Advanced stages of cytopathic effect were illustrated by cells showing a marked increase in electron-density. These features were not observed in uninfected control cultures.
Animals↗
Retroviral expressed hemagglutinin-neuraminidase protein protects chickens from Newcastle disease virus induced disease.
The hemagglutinin-neuraminidase (HN) gene and the phosphoprotein (P) gene of Newcastle disease virus (NDV) were inserted into a replication competent avian leukosis virus vector. The expression of the HN gene from this vector in chick embryo cells has been previously reported. The P gene is also expressed from this vector in chick embryo cells. The retroviruses were used to immunize 4-week-old chickens. Birds receiving the virus containing the HN gene developed low levels of serum HI titers and NDV neutralization titers. Upon challenge, all birds vaccinated with the HN gene containing virus were protected from disease but not viral infection and replication. In contrast, birds immunized with the P gene containing retrovirus developed more severe clinical signs of disease earlier than birds receiving no immunization or retrovirus alone. The results obtained with the HN gene may have potential application to reducing disease due to NDV genetically engineered vaccines.
Animals↗
Epidemiologic association between antibody titres against bovine virus diarrhoea virus, rinderpest disease virus and infectious bovine rhinotracheitis virus in a buffalo herd.
The association between antibody titres against bovine virus diarrhoea virus (BVDV), infectious bovine rhinotracheitis virus (IBRV) and rinderpest disease virus (RPDV) in buffaloes was investigated in a cross-sectional study. Thirty-six lactating buffaloes from a herd in Landhi Cattle Colony, Karachi were bled and serum samples subjected to a micro-neutralisation test at the Plum Island Animal Disease Center, USA, to categorise each buffalo either as positive or negative against each of 3 viral antigens. Log-linear analysis was used to evaluate the association among 3 categorical variables. The "best-fitting" log-linear model was the model of complete independence. This model includes all 3 main effects (BVDV, IBRV, RPDV), suggesting that the seropositivity of buffaloes against these viral antigens tended to occur independently. Estimates of parameters of the model showed that the proportion of buffaloes seropositive (97.2%) to RPDV antigen tended to be higher than expected, whereas the proportion of BVDV seropositive (30.6%) and IBRV seropositive (16.7%) buffaloes tended to be smaller than expected.
Animals↗
Differential sensitivity of two related viruses, Newcastle disease virus and Sendai virus, to interferon in mouse Had-2 cells: selective inhibition of translation of NDV mRNA.
Had-2, a mouse mutant cell line derived from FM3A, constitutively releases interferon-alpha and beta and acquires resistance to Newcastle disease virus (NDV) and other viruses. However, Had-2 was found as susceptible to Sendai virus (HVJ) as FM3A. Even when Had-2 cells were infected simultaneously with NDV and HVJ, only the replication of NDV was inhibited, while that of HVJ was not. Northern blot hybridization analysis indicated that accumulation of NDV-specific primary transcripts was somewhat reduced in Had-2, but the reduction was insufficient to critically suppress the viral replication. Moreover, this decrease was not observed in the presence of cycloheximide, and a closely comparable amount of the primary transcripts was detected in both Had-2 and FM3A cells. The mRNA accumulated in the presence of cycloheximide was translated efficiently on removal of the inhibitor in FM3A cells, but not at all in Had-2 cells. Thus the translation of NDV mRNA was the major target of interferon in Had-2 cells. The fact that the synthesis of HVJ proteins was unaffected in Had-2 cells may imply that a host-cell component that distinguishes between NDV and HVJ mRNAs is involved in their translation.
Animals↗
Influence of vaccination on Aujeszky's disease virus and disease transmission.
Parenteral vaccination of fattening pigs with either modified live or inactivated Aujeszky's disease virus did not prevent infection with field strain virus or the development of clinical disease. The duration and severity of the clinical syndrome was, however, reduced and vaccinated pigs did not suffer the severe weight loss and high mortality experienced by non-vaccinated pigs in the acute phase of disease. The range of tissues in which challenge virus replication took place was more restricted in vaccinated animals and the concentration of virus in infected tissues was reduced. Vaccination shortened the duration of field virus excretion and carriage in the tonsil. Replication of modified live vaccine virus was restricted to the site of inoculation in the neck and associated lymph nodes for two days after vaccination and it was not excreted by vaccinated pigs. Attempts to infect pigs by feeding them tissues taken from non-vaccinated or vaccinated pigs soon after challenge infection were unsuccessful.
Animals↗
[On the hitherto unknown, in monkeys originating infectious disease: Marburg virus disease].
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Adult↗
PCR amplification of a specific double-stranded RNA region of Fiji disease virus from diseased sugarcane.
A 450-bp region from one species of the segmented dsRNA genome of Fiji disease virus (FDV) was amplified from total nucleic acid extracts of diseased plants by reverse transcription with MMLV, followed by amplification with Taq DNA polymerase (RT-PCR). Other FDV-specific regions (c 150 bp and c 270 bp) were also amplified from the dsRNA template. FDV cDNA was only synthesised when the viral dsRNA template was boiled and quenched with FDV-specific or random hexamer primers. The reverse transcriptase/DNA polymerase enzyme rTth appeared to yield only the 150 bp fragment from the dsRNA template under the conditions used. The level of sensitivity of RT-PCR for purified FDV dsRNA was 100 ag, approximately 10(4)-fold more sensitive than detection with biotinylated DNA probe.
Base Sequence↗
Genetic and phenotypic correlations between antibody responses to Escherichia coli, infectious bursa disease virus (IBDV), and Newcastle disease virus (NDV), in broiler lines selected on antibody response to Escherichia coli.
The genetic control of antibody (Ab) response to Escherichia coli (EC), infectious bursa disease virus, and Newcastle disease virus and the genetic and phenotypic correlation between these Ab responses, were evaluated under farm conditions in which chicks were simultaneously exposed to these antigens. The experimental population comprised five groups: two lines divergently selected for high (HH) or low (LL) Ab response to EC vaccination; a commercial broiler dam-line (CC), from which HH and LL had been derived; and the HH x CC and LL x CC hybrid groups (HC and LC, respectively). Lines LL and HH expressed similar symmetric divergence to all three antigens. The ranking of the LL, LC, CC, HC, and HH genetic groups according to their mean Ab responses and their very high linear correlation with the LL vs. HH genomic scale clearly indicate the additive nature of the genetic divergence between these lines. Several estimates of correlation were calculated between Ab responses of each pair of antigens and between BW and Ab to each antigen. The high correlation between group means, the near-zero within-group correlation, and the low phenotypic correlation indicate the strongly positive genetic correlation between Ab responses and no correlation with BW. The results of this study suggest that overall immunocompetence of commercial broilers can be improved by selection for high Ab response of young chicks to controlled immunization with a single antigen, without counteracting further selection for high BW.
Animals↗
Approaches to the control of respiratory virus diseases.
Viruses of various biological types are known to cause a wide range of acute respiratory infections, ranging from mild colds and catarrh to severe bronchiolitis and pneumonia. Bacteria also cause respiratory diseases including serious conditions such as otitis media and pneumonia. The whole situation is complex and to understand the epidemiology we also need to consider nutrition, environment, climate, and chronic diseases. Acute respiratory viral diseases are very common in all areas of the world and contribute to morbidity and probably to mortality. There are no antiviral drugs or vaccines which would be generally useful. It ought to be possible to reduce the effects of these diseases by improving the standard of general management of cases. This would involve careful nursing, administration of appropriate antibiotics, and referral of severe cases to a properly staffed and equipped hospital. Further research is needed to develop ways of doing this and to evaluate the results.
Acute Disease↗
Persistence of Escherichia coli, Salmonella choleraesuis, Aujeszky's Disease virus and Blue Eye Disease virus in ensilages based on the solid fraction of pig faeces.
AIMS: This study was carried out to determine the survival time of Escherichia coli, Salmonella choleraesuis, Aujeszky's Disease virus and Blue Eye Disease virus in ensilages based on the solid fraction of pig faeces. METHODS AND RESULTS: The four micro-organisms were inoculated into microsilos based on the solid fraction of pig faeces, sorghum and molasses. They were left for 0, 7, 14, 28 and 56 days, after which the state of each microsilo was evaluated, and isolation of the inoculated agents was attempted. The four inoculated agents were isolated only on day 0 of ensilage. The viral agents were identified through the cytopathic effect and fluorescence. CONCLUSIONS, SIGNIFICANCE AND IMPACT OF THE STUDY: It is concluded that ensilages based on the solid fraction of pig faeces appear to reduce the risk of the transmission of the agents inoculated in this study and help to reduce the environmental impact by using the solid in animal feed.
Animals↗