Epidemiological and clinical observation of a minor localized epidemic of acute febrile disease (Coxsackie virus disease).
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Complement in human serum inactivated several enveloped viruses, but for some viruses the degree of inactivation depended on their passage history. In short, human serum detected cell-induced modifications of virions. Normal human serum, lacking detectable neutralizing antibodies to the virions, inactivated lymphocytic choriomeningitis virus (LCMV) and Newcastle disease virus (NDV) when the viruses were passed through some cell lines but not others. Host cell modification was further documented with LCMV since antibody to the cell (in conjunction with a complement source) inactivated virus produced by that cell. The mechanism by which human serum inactivated LCMV passed through L cells was determined. By using serum immunochemically depleted in the classical complement pathway component C4 and/or the alternative complement pathway component factor B, as well as other methods, it was shown that LCMV was inactivated via the classical complement pathway. Absorption and immune precipitation experiments indicated that the inactivation of LCMV by complement was mediated by natural antibody directed against the host (L-929) cell. NDV grown in chick embryo cells could be unactivated by either complement pathway in the absence of the other. A requirement for antibody could not be demonstrated in the NDV system. On the basis of these data it is proposed that alterations in virulence dependent upon passage of the virus in cells or animals may be partially explained by changes in virus sensitivity to human serum inactivation.
Borna disease virus is a neurotropic negative-strand RNA virus that infects a wide range of vertebrate hosts, causing disturbances in movement and behavior. We have cloned and sequenced the 8910-nucleotide viral genome by using RNA from Borna disease virus particles. The viral genome has complementary 3' and 5' termini and contains antisense information for five open reading frames. Homology to Filoviridae, Paramyxoviridae, and Rhabdoviridae is found in both cistronic and extracistronic regions. Northern analysis indicates that the virus transcribes mono- and polycistronic RNAs and uses termination/polyadenylylation signals reminiscent of those observed in other negative-strand RNA viruses. Borna disease virus is likely to represent a previously unrecognized genus, bornaviruses, or family, Bornaviridae, within the order Mononegavirales.
Two hundred thirty specimens of wild birds were collected from some areas in Heilongjiang Province during the period of 2003-2004, including two batches of specimens collected randomly from a same flock of mallards in Zhalong Natural Reserve in August and December, 2004, respectively. Primary virus isolation and identification for avian influenza virus (AIV) and Newcastle disease virus (NDV) were performed. The results showed that only two specimens of young mallards collected from Zhalong Natural Reserve in August, 2004 were positive to AIV (isolation rate 0.9%), and one strain (D57) of these two virus isolates was identified to be H9 subtype by hemagglutination inhibition test. Meanwhile, the two batches of blood serum samples of mallards from Zhalong were also examined for antibodies against AIV and NDV. Among 38 blood serum samples collected in August, antibodies against the hemagglutinin of H1, H3, H5, H6 and H9 subtypes of AIV were found in 1, 0, 2, 0 and 8 samples, respectively; and 11 samples were found with antibody against NDV. Whereas the NDV isolation in both two batches of specimens of mallard was negative, all of the 32 blood serum samples collected in December were negative for antibodies against AIV and NDV.
Helical nucleocapsids of each of the paramyxoviruses simian virus 5 (SV5), Newcastle disease virus (NDV), and Sendai virus have been isolated in two different forms. One form contains larger protein subunits and is obtained from mature virions or infected cells dispersed by ethylenediaminetetraacetic acid. The other form possesses smaller subunits and is obtained from infected cells dispersed by trypsin. The estimated molecular weights of the larger subunits in the three viruses are similar: SV5, 61,000; Sendai virus, 60,000; NDV, 56,000. The smaller nucleocapsid subunits are also very similar: SV5, 43,000; Sendai virus, 46,000; NDV, 47,000. The helical nucleocapsid composed of the smaller subunit appears to be less flexible and more stable than that formed by the larger subunit. There is suggestive evidence that conversion of the larger subunit to the smaller by proteolytic cleavage may occur intracellularly. The possibility that such a mechanism could be involved in the accumulation of nucleocapsid in cells persistently infected with paramyxoviruses is discussed.
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Infectious bursal disease virus (IBDV) causes a highly immunosuppressive disease in chickens. Currently available, live IBDV vaccines can lead to generation of variant viruses. We have developed an alternative vaccine that will not create variant IBDV. By using the reverse genetics approach, we devised a recombinant Newcastle disease virus (NDV) vector from a commonly used vaccine strain LaSota to express the host-protective immunogen VP2 of a variant IBDV strain GLS-5. The gene encoding the VP2 protein of the IBDV was inserted into the most 3'-proximal locus of a full-length NDV cDNA for high-level expression. We successfully recovered the recombinant virus, rLaSota/VP2. The rLaSota/VP2 was genetically stable, at least up to 12 serial passages in chicken embryos, and was shown to express the VP2 protein. The VP2 protein was not incorporated into the virions of recombinant virus. Recombinant rLaSota/VP2 replicated to a titer similar to that of parental NDV strain LaSota in chicken embryos and cell cultures. To assess protective efficacy of the rLaSota/VP2, 2-day-old specific-pathogen-free chickens were vaccinated with the recombinant virus and challenged with a highly virulent NDV strain Texas GB or IBDV variant strain GLS-5 at 3 weeks postvaccination. Vaccination with rLaSota/VP2 generated antibody responses against both NDV and IBDV and provided 90% protection against NDV and IBDV. Booster immunization induced higher levels of antibody responses against both NDV and IBDV and conferred complete protection against both viruses. These results indicate that the recombinant NDV can be used as a vaccine vector for other avian pathogens.
The protein component of Alzheimer's disease amyloid (neurofibrillary tangles, amyloid plaque cores and congophilic angiopathy) is an aggregated polypeptide with a subunit mass of approximately 4 kDa (the A4 monomer). The aggregational properties of this monomer may explain the amyloidogenic nature of the protein: the native monomer forms dimers, tetramers and higher oligomeric species which are dependent on pH, ionic strength and concentration; the synthetic peptide corresponding to residues 1-28 spontaneously forms fibrils in vitro. Based on the degree of N-terminal heterogeneity, the A4 monomer aggregates first in neurons and later in the extracellular space. Using antisera raised against synthetic peptides, we can demonstrate that the N-terminus contains an epitope for neurofibrillary tangles, and the inner region of the molecule contains an epitope for the extracellular amyloid fibrils. There is a non-protein component of the amyloid (inorganic residues of aluminium silicate) which may be important in the deposition of the amyloid fibrils. There are several intriguing similarities between the amyloid fibrils and proteins of Alzheimer's disease when compared to the scrapie-associated filaments and proteins of the unconventional virus diseases (scrapie, kuru, Creutzfeldt-Jakob disease). Although there is no sequence homology between the proteins, we suspect they are formed as a result of similar biochemical processes. If the scrapie proteins and filaments are an integral part of the infectious agent, it follows that Alzheimer's disease is also an infectious process similar to scrapie. As they are host-encoded proteins, it is still feasible that both types are pathological by-products of independent diseases.
Sendai and Newcastle disease viruses were tested for their induction potential in the production of human lymphoblastoid interferon [HuIFN-alpha(Ly)] from Namalva cell cultures. Tests were performed at multiple induction levels, for two induction periods, and on primed and nonprimed cell cultures. Sendai virus proved statistically more effective overall; priming and induction period had no significant effect.
A nested reverse transcription (RT) polymerase chain reaction (PCR) assay was evaluated for differentiating reference bovine viral diarrhea virus (BVDV) strains, BVDV from diagnostic accessions, modified-live virus (MLV) BVDV strains in bovine viral vaccines, and a reference border disease virus (BDV). The detection level of this assay was compared to viral infection in cell culture. The PCR assay was used to distinguish 3 ruminant pestiviruses, types 1 and 2 BVDV, and type 3 BDV. The consensus (first) PCR assay detected all 3 ruminant pestiviruses, a result of the shared sequence homology. The consensus PCR product was subjected to a second (nested) PCR which used type-specific primers. The nested PCR was able to differentiate the 3 ruminant pestiviruses. Viral stocks of BVDV were diluted 10-fold and processed for the 2-step PCR assay. The sensitivity of this 2-step PCR assay was compared to viral infectivity in cell culture based on identical volumes of the system tested (cell culture assay and processing for RNA). The RT-PCR type-specific assay differentiated BVDV laboratory reference strains (12), diagnostic laboratory isolates (15), 2 MLV BVDV vaccine strains, and a BDV strain. The 30 ruminant pestiviruses typed included: (1) 27 reference strains and diagnostic laboratory isolates; 18 cytopathic (CP) type 1 strains, 3 CP type 2 strains, 3 noncytopathic (NCP) type 1 strains, and 3 NCP type 2 strains; (2) 2 MLV strains, type 1; and (3) 1 CP BDV type 3. The PCR assay had a detection limit of 10 TCID50/0.025 mL of virus when 3 separate BVDV were tested. This 2 step RT-PCR assay would be useful for the typing of ruminant pestiviruses, particularly BVDV isolates from the diagnostic laboratory.
Despite progress in understanding the molecular biology and pathobiology of Borna disease virus, its epidemiology and role in human disease remain controversial. The challenges encountered in this field are a paradigm for the investigation of diseases potentially linked to complex host-microorganism interactions.
The polypeptides of three paramyxoviruses (simian virus 5, Newcastle disease virus, and Sendai virus) were separated by polyacrylamide gel electrophoresis. Glycoproteins were identified by the use of radioactive glucosamine as a carbohydrate precursor. The protein patterns reveal similarities among the three viruses. Each virus contains at least five or six proteins, two of which are glycoproteins. Four of the proteins found in each virus share common features with corresponding proteins in the other two viruses, including similar molecular weights. These four proteins are the nucleocapsid protein (molecular weight 56,000 to 61,000), a larger glycoprotein (molecular weight 65,000 to 74,000), a smaller glycoprotein (molecular weight 53,000 to 56,000), and a major protein which is the smallest protein in each virion (molecular weight 38,000 to 41,000).
Eleven Polish and Hungarian isolates of Infectious bursal disease virus (IBDVs) obtained in the 70/80s (early IBDV) and in the 90s (recent IBDV) were characterized in an Antigen-Capture-ELISA with a panel of neutralizing monoclonal antibodies (Mabs), and by nucleotide sequencing of the VP2 variable domain (vVP2). The viruses were compared with reference IBDV strains, among others with Faragher 52/70 (F52/70, classical, isolated 1970), 89163 (typical very virulent-vvIBDV, isolated 1989) and 91168 (antigenically modified vvIBDV, isolated 1991). Only one of the early isolates (Hungarian strain P1) proved antigenically and genetically similar to F52/70. Other early isolates exhibited no reactivity versus Mabs 3, 4, 5 and/or 8 and had a common previously unrecognized combination of amino acid changes in vVP2. The recent isolates all proved antigenically and genetically related to typical vvIBDV strain 89163, except the Polish isolate 93/35 which proved related to the 91168 strain although no epidemiological relationship had been documented between these viruses in the field. Phylogenetic analysis confirmed that the non-P1 early IBDVs represent a previously unrecognized group among serotype 1 IBDVs. It is discussed whether these early isolates are derivatives of the F52/70-like viruses that might still be present in the field, or whether they represent early IBDV strains that might have been present prior to and progressively replaced by the F52/70-like viruses, as the latter have been replaced by vvIBDVs in the late eighties.
The effect of potent sheep anti-mouse interferon globulin was investigated in several different experimental virus diseases of mice. In anti-interferon globulin-treated mice infected intraperitoneally with herpes simplex virus (HSV) type I, the latent period was shortened, and the overall LD50 was increased several hundredfold compared to virus-infected control mice. When HSV was inoculated subcutaneously all anti-interferon globulin-treated mice died, whereas only 5% of virus-infected control mice died. Subsequent treatment with anti-interferon globulin of previously HSV-infected mice did not result in reactivation of HSV. Treatment of adult mice with anti-interferon globulin resulted in an earlier appearance of MSV-induced tumors, a greater number of mice bearing tumors, an increase in tumor size, and an increase in the duration of tumors. All tumors eventually regressed despite reinjection of anti-interferon globulin. Anti-interferon globulin treatment resulted in a rapid onset of disease and death in adult mice inoculated (intranasal) with VSV and in newborn mice infected with NDV. Anti-interferon globulin exerted no effect on the course of influenza virus infection of mice. We conclude that the early production of interferon is an importane element in the response of the mouse to several viruses exhibiting different pathogeneses.
A 289 bp cDNA fragment from the 5'-untranslated region (UTR) of 16 bovine viral diarrhoea virus (BVDV) isolates was amplified by reverse transcription and polymerase chain reaction, and sequenced by dideoxy DNA sequencing. The sequence showed greater than 90% homology between the isolates and BVDV NADL in this region, and greater than 97% homology within a 72 base sub-region (nt 314-386). The 289 bp fragment was then used as a probe for rapid detection of BVDV and border disease virus (BDV) from cell culture samples by dot-blot hybridization. This probe hybridized to 100% of BVDV isolates (n = 78) and 100% of BDV isolates (n = 9), but not to the uninfected BT cells or other bovine infectious agents. A shorter probe from the more conserved sub-region also was tested for hybridization with some of the isolates, and the results were similar to those using the longer probe. These results suggest that the 5'-UTR is highly conserved among BVDV and BDV isolates, and may be used as a potential probe for rapid detection of BVDV and BDV in clinical and cell culture samples from cattle and sheep.
The commercial flocks in Yucatan, Mexico are free of Newcastle disease virus (NDV) in its velogenic viscerotropic form, but little is known about the disease status of backyard poultry. A seroprevalence survey in 30 villages using haemagglutination inhibition (HI) tests for infectious bronchitis virus (IBV) and NDV antibodies was carried out from December 1997 to June 1998. The seroprevalences were 56.5% (95% CI 50-63%) for IBV and 2.2% (95% CI 0.5-3.8%) for NDV. All the villages had chickens that were positive for antibodies to IBV and nine of the villages had chickens that were positive for antibodies to NDV. This suggests that IBV may be responsible for a large proportion of the respiratory disease observed in backyard chickens in Yucatan. The implications of these findings are discussed, including the highly susceptible status of the backyard chickens in Yucatan to NDV and the possibility of this virus being one cause of the syndrome known as mortandad by the local people.
Virions of bluetongue virus (BTV), epizootic haemorrhagic disease virus (EHDV) and African horsesickness virus (AHSV) can be converted to core particles by treatment with chymotrypsin and magnesium. The conversion is characterized by the removal of the 2 outer capsid polypeptides of the virion. The loss of these 2 proteins results in an increase in density from 1,36 g/ml to 1,40 g/ml on CsCl gradients. The BTV, EHDV and AHSV core particles have an associated double-stranded RNA dependent RNA transcriptase that appears to transcribe mRNA optimally at 28 degrees C. It was found, at least in the case of BTV, that this low temperature preference is not an intrinsic characteristic of the transcriptase, but is due to a temperature-dependent inhibition of transcription at high core concentrations.
The biology of Borna disease virus (BDV) strongly supports the likelihood of human infection with BDV or a variant of BDV. Thus far, the evidence supporting BDV infection in humans has initiated much controversy among basic and clinical scientists; only time and additional research will support or refute the hypothesis of human BDV infection. Until an assay of acceptable specificity and sensitivity has been developed, validated, and used to document human BDV infection, scientists cannot reasonably begin to associate BDV infection with specific disease syndromes. Clinical studies seeking causal associations between BDV infection and specific diseases must ensure the proper identification of the BDV infection status of patients and control subjects by using a validated, highly sensitive, and highly specific assay (or series of assays). For clinical studies, a highly sensitive "screening" test followed by a highly specific confirmatory test will be of significant benefit. Although it is possible to formulate hypotheses about the clinical outcomes of human BDV infection based on animal model work, to date no human disease has been causally linked to human BDV infection. Scientists all over the world are actively pursuing these issues, and with continuing advances in clinical and basic BDV research, the answers cannot be far away.