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At least 19 recordsLinked to original sources
PubMed1975

Comparison of canine distemper viral strains: an electron microscopic study.

A canine distemper (CD) viral strain, designated R252, originally obtained from a dog with demyelinating encephalomyelitis has been shown to reproduce this disease in gnotobiotic dogs in a high incidence in contradistinction to other CD viral strains which produce an acute fatal disease. Because comparision of R252 strain with the Snyder Hill (SH) and Onderstepoort (Ond) strains revealed differences in in vitro behavior, the 3 viruses were ultrastructurally investigated. The results revealed differences among the 3 viruses: Cytoplasmic nucleocapsid aggregates were characteristic of R252, diffuse aggregates of nucleocapsids were characteristic of SH, and although budding viral particles were recognized in Ond-infected cells, few nucleocapsids were seen in the cytoplasm. Cytoplasmic fibrillar structures were characteristic of R252- and Ond-infected cells. The budding viral particles observed with R252 and SH were similar, whereas Ond budding particles seemed to contain fewer nucleocapsids. Intranuclear inclusions recognized in R252- and SH-infected cultures appeared as areas of clearing of nucleoplasm along with disruption of the nucleolus. The presence of nucleocapsid-like structures was variable. Ultrastructurally, the cytoplasmic inclusions in cells infected with all 3 viruses progressed from focal aggregates of nucleocapsids to electron-dense bodies.

Animals↗
PubMedDate not supplied

[Interfering and interferonogenic activity of attenuated and original para-influenza viral strains].

A higher interfering activity of attenuated (vaccine) strains of parainfluenza virus types 1, 2 and 3 which had undergone a long-term adaptation to cell cultures as compared to the original viruses was established. The interferon-inducing activity of vaccine parainfluenza virus types 2 and 3 was also higher than that of the original viruses. The high interfering and interferon-inducing activity of attenuated parainfluenza virus strains of type 2 and 3 correlated with reduced virulence of these variants for man. These tests may be used for the assessment of virulence of parainfluenza virus strains type 2 and 3 in the laboratory.

Cells, Cultured↗
PubMed1977

[Test of an attenuated viral strain of TGE as a vaccine].

A live vaccine was produced using a local strain P of the virus of the transmissive gastroenteritis, arrenuated in cell cultures. The vaccinated pregnant sows had high-titer serum and colostrum virus-neutralizing antibodies. In the first days following farrowing there were in the colostrum ummunoglobulins of the Igg class that prevailed, however, IgA and IgM proved more effective in the virus-neutralizing test. Newborn pigs acquired passive immunity at about the 24th hour after the intake of colostrum. They withstood a challenge with a virulent virus.

Animals↗
PubMed2025

Integrated Seroprevalence and Genome-Based Study of SARS-CoV-2 Viral Strains in N'Djamena: Insights Into Chad's COVID-19 Epicenter.

The COVID-19 epidemic has shown regional variations in transmission and outcomes. As a primary hotspot in Chad, N'Djamena is crucial for comprehensive epidemiological investigation. Our study employed two methodologies: seroprevalence data collection and whole-genome sequencing of SARS-CoV-2 strains. This dual approach assessed population exposure and virus genetic diversity. Seroprevalence data indicated broader exposure than confirmed cases suggested, and genome sequencing identified multiple strains, including globally recognized variants of concern. Integrating these data provided insights into transmission dynamics, potential herd immunity thresholds, and the impact of specific variants on disease progression. Our findings underscore the importance of integrated, multidisciplinary research in infectious disease epidemiology and inform targeted public health strategies, including social measures and vaccination, to combat infectious diseases in N'Djamena.

Humans↗
PubMed1977

Comparison of intestinal (Illinois strain) and cell culture-adapted (M-HP strain) viral populations of transmissible gastroenteritis of swine.

Intestinal and cell culture-adapted viral populations of transmissible gastroenteritis (TGE) of swine were compared by means of sucrose gradient centrifugation, immunnofluorescence, electron microscopy, immune electron microscopy, statistical analysis of the number of plaque-forming units, and ultraviolet sensitivity. Results indicated that the size range and general coronavirus morphologic characteristics were shared by both viral populations. Marked morphologic variations existed among particles from both populations. Unlike the cell culture-adapted virus, the Illinois virus of intestinal origin was infractions representing 2 bands of infectivity which were isolated by the sucrose gradient centrifugation method. The intestinal and cell culture-adapted TGE viruses were similar in antigenicity and in sensitivity to ultraviolet irradiation. There was no indication of a 2nd virus in addition to the coronavirus described as the cause of TGE.

Animals↗
PubMed1977

[Experimental infection of man using viral strains of bovine papular stomatitis, orf, pseudocowpox and milker's nodule].

An account is given of the close correlations that exist between virus strains of bovine papular stomatitis, orf, pseudocowpox, and milker's nodule. Reference is made to literature data on natural infection of man with the above virus strains. A report then is presented on experimental infection of human volunteers, using paravaccine birus. While fairly tough and elevated nodules, 4 mm to 5 mm in diameter, were produced on the probends' skin, no re-isolation of virus was achieved.

Animals↗
PubMed1978

[Comparative studies of the virulence of some Aujeszky's disease viral strains].

Clinical, virological, morphological, and immunofluorescence investigations were carried out on 22 pigs experimentally infected with two strains--a virulent one (V) of a 10(-3) titer, and a slightly virulent one (K) of a 10(-7) titer--of the virus of Aujeszky's disease as well as on contact pigs. Results revealed variations in the clinical and morphological manifestation of the disease in the individual groups. They were shown to be due to the strains of the virus that varied in virulence and tissue tropism. In the strain B-infected animals there were clinical symptoms characteristic of the disease, and the morphological changes in the central nervous system were of the nonsuppurative encephalitis type. The pigs infected with the K strain of the virus showed no clinical symptoms, while the contact animals manifested only respiratory troubles as well as interstitial pneumonia. It was demonstrated that the strains of slight virulence had weak nervotropic and pronounced pneumotropic characters. Complex virologic, morphologic and immunofluorescence investigations can be used for the diagnosis of the atypical forms of Aujeszky's disease and for the differentiation of the virulent from the slightly virulent strains of the virus.

Animals↗
PubMed1976

Adenosine triphosphatase activity in myxoviruses.

Sendai and PR 8 viral particles show Na+-K+-ATPase activity, an enzymatic activity which is assumed to be a typical plasma membrane marker and which probably derives from the host cell membrane. Attention has been paid to the peculiar behaviour of Na+-K+-ATPase activity in the two viral strains upon hypoosmotic treatment: Sendai viral particles show enzymatic activity only after swelling, when for PR 8 particles the reverse is true. The results obtained are discussed as suggesting a different organization in the envelope of the viral strains. This approach is supported also by morphological evidence concerned with the osmotic response of viral particles.

Adenosine Triphosphatases↗
PubMed2026

MicroRNAs in Veterinary Viral Diseases: A Comprehensive Review from Molecular Mechanisms to Clinical Translation.

MicroRNAs (miRNAs) are small non-coding RNA molecules, approximately 22 nucleotides in length, that regulate post-transcriptional gene expression and have emerged as pivotal modulators of host-virus interactions. Veterinary viral diseases continue to pose substantial challenges to animal health, livestock productivity, food security, and public health, particularly due to their zoonotic potential. While miRNA research has advanced considerably, a comprehensive and critically integrated understanding of their biological functions and clinical applications across veterinary viral diseases remains incomplete. This comprehensive critical narrative synthesis addresses four overarching research questions: (1) What conserved and species-specific miRNA-mediated mechanisms govern major veterinary viral diseases? (2) What contextual factors determine antiviral vs. proviral duality? (3) To what extent do circulating miRNA signatures offer diagnostic and prognostic utility? (4) What translational barriers currently prevent clinical implementation, and how can the One Health framework help overcome them? Integrating three interconnected dimensions-molecular mechanisms, pathogen-specific responses, and translational applications-the review synthesizes evidence across PRRSV, avian oncogenic viruses (MDV, ALV), the immunosuppressive IBDV, FMD, BVDV, Ebola, Hendra, Rabies, and aquatic viral diseases. A key contribution of this review is the proposal of a four-axis contextual framework that explains the antiviral/proviral duality of miRNAs, and a 'One miRNA, One Health' convergence model with a concrete implementation roadmap. Key findings include: (a) a four-axis contextual framework (cell type, infection stage, viral strain, host-viral miRNA competition) that explains the antiviral/proviral duality; (b) virus-encoded miRNAs (v-miRNAs) as lower-risk therapeutic targets due to their absence from uninfected host genomes; (c) circulating miRNA biomarkers validated only at proof-of-concept stage (TRL 1-3), with no veterinary product yet at TRL ≥4; and (d) zoonotic conservation of miR-155, miR-146a, miR-21, and miR-122 across human and veterinary pathogens, supporting a 'One miRNA, One Health' convergence strategy. Critical short-term priorities are standardized pre-analytical protocols, open-access veterinary miRNA databases, and multicenter validation in natural infection cohorts.

Antiviral therapy↗
PubMed2026

Genetic Diversity of BK Polyomavirus Among Renal Transplant Recipients in Yunnan, China.

BK polyomavirus (BKV) infection, a common complication following kidney transplantation, can lead to BKV-associated nephropathy (BKVN). Molecular genetic studies have classified BKV into four genotypes (I-IV); however, comprehensive molecular characterization of BKV strains circulating in China remains limited. This study aimed to elucidate the predominant subtypes and clinical infection characteristics of BKV strains among kidney transplant recipients in Yunnan, a province in southwestern China. PCR-amplified BKV DNA sequences from kidney transplant recipients were aligned with reference strains and subjected to phylogenetic analysis. The viral VP1 gene was successfully amplified from 180 participants, spanning 16 ethnic groups. Genotype I was the predominant viral strain (56.66%, 102/180), followed by genotype IV (43.33%, 78/180), while genotypes II and III were not detected. Among genotypic subtypes, IVc-1 was most prevalent (40.0%, 72/180), followed by Ic (38.3%, 69/180) and Ib-1 (18.3%, 33/180). IVa-1 and IVa-2 were rare, identified in only 0.6% (n = 1) and 2.2% (n = 4) of cases, respectively. No significant differences in sex, age, BKVN incidence, BK viremia, or viruria were observed between patients with BKV-I and BKV-IV infections. Among the five confirmed BKVN cases, two were genotyped as subtype Ic, one as Ib-1, and two as IVc-1. Clinical phenotypes were also comparable between patients with BKV-I and BKV-IV infections. This study represents the largest single-center sequencing analysis of BKV in kidney transplant recipients in China, offering a valuable genomic resource for future research.

Humans↗
PubMed1977

[Pathogenetic mechanisms of tick-borne encephalitis].

The main cause of progressive forms of tickborne encephalitis is a prolonged persistence of certain viral strains in the brain. Although there are no virals with a selective capability to lead only to an acute or chronic encephalitis, nevertheless in the epidemiological process there is a selection of virals capable of bringing on chronic forms of the disease. In cases of an incapacity of immunological factors bor a defence during the initial phase of the infectious process there may be prerequisites to a fixation of the virals in the brain and a chronic development of the neuroinfections. It is necessary to differentiate active neuroinfectious processes due to persistent virals and postencephalitic reparative-dystrophical syndromes. This permits to avoid a hyperdiagnosis and more reasonably select therapeutical measures in the evaluation of their effectivity.

Animals↗
PubMed1979

Temporal appearance, geographic distribution, and species of origin of bluetongue virus serotypes in the United States.

Beginning in 1973, all available laboratory and field strains of bluetongue virus (BTV) from the United States were serotyped. Of the viral strains serotyped, 27 were collected from 1953 through 1972; 173 were collected from 1973 through 1977. Although 20 BTV serotypes have been found worldwide, only BTV serotypes 10, 11, 13, and 17 have been found in the United States. Since 1973, serotypes 11 and 17 have been the prevalent serotypes. Samples were collected over a 24-year period in the United States and represent a wide geographic area and diverse host sources (sheep, cattle, wild ruminants, and insect vectors). The collection was not a statistical sampling.

Animals↗
PubMed1976

[Avidity criteria in assessing the functional activity of antigens, antibodies and non-specific serum inhibitors on a model of the kinetic reaction of hemagglutination suppression with arboviruses].

The functional activity of some arboviruses of groups A and B, of the antibodies and serum inhibitors was studied on a model of the kinetic hemagglutination inhibition test (HAI) by different avidity criteria (velocity, completeness and stability of formation of a neutral complex). The avidity indices of the antigens, antibodies and the inhibitors proved to depend on the group, species and strain peculiarities of the arboviruses, the method of preparation of the antigen, the biological species of the donor of the immune and normal blood sera, the method of treatment of the sera and a number of other factors. There proved to be no constan-correlation between the avidity of the strain and the avidity of the serum immune to it. Inhibitors of the normal rabbit and human sera were not less effective in comparison with the specific antibodies to a number of viral strains of tick-borne encephalitis and Japanese encephaliti or even exceeded them by the avidity indices to the antigens in the HAI test. The most active (functionally) strains can be recommended for obtaining high-quality viral (antigenic and serum) preparations.

Animals↗
PubMed1978

Small plaque variant transmissible gastroenteritis virus.

A small plaque (SP) variant transmissible gastroenteritis (TGE) virus strain that may be useful in the control of TGE in swine has been developed and tested. This strain was derived from a persistently infected swine leukocyte cell line originally infected with a virulent TGE virus. The SP viral strain was avirulent for 3-day-old susceptible pigs and pregnant gilts. The SP virus elicited protective antibody when inoculated into pregnant gilts oral/intranasally, or intramammarily, or by both of these routes. The morbidity and mortality of their passively immune suckling pigs were 62% and 14%, respectively.

Animals↗