African horsesickness virus (No.3922, Type 7), attenuated for the horse by serial passage in suckling mouse brain, was studied at various passage levels to determine whether any change in the biophysical characters of the infectious particles had occurred. during the process of attenuation. Such changes were indeed observed. Propagation of the virus in tissue culture was accomplished only after the modification of standard culture media by the addition of egg white, a complex substance containing a number of proteins including the enzyme lysozyme. Some evidence is presented to show that the presence of egg white materially assisted in the successful cultivation of horsesickness virus; as well as in the formation of plaques in monolayers ·of cultured cells. Electron micrographs of horsesickness virus obtained from these cultured cells, and the results of a study of the fine structure of infected mouse nervous tissue, are presented. A remarkable change in the buoyant density of the infectious particles of this horsesickness virus was found to occur during attenuation. The 'wild' or virulent strain was found to consist mainly of particles of density 1.26 gm/ml. The attenuated strain however proved to be composed of particles with deneities quite different from that of the wild strain, predominantly 1.21 and 1.34 gm/ml. This alteration of the buoyant appeared to be directly related to the degree of attenuation. Studies in electrophoresis using a newly designed apparatus showed that the wild strain of horsesickness virus is homogeneous in its migration in an electric field. The attenuated strain showed a changed electrophoretic pattern· indicating the presence of particles of different mobilities. As in density gradient analysis, electrophoresis showed a fundamental difference between the wild and attenuated strains of this virus. It was possible also to show a correlation between the slowly migrating component of the attenuated strain and the fraction of higher density. The sedimentation coefficient of the infectious particles of the No.3922 strain of horsesickness virus was studied at various stages of attenuation ·and the particle size at three passage levels were calculated. The particle size and other characteristics determined in this way were compared with the results of measurements obtained from ultrafiltration of the virus through collodion membranes. It was found that the diameter of the infectious particles of the attenuated strain is greater than that of the wild strain. This study shows that physical measurements may be used to give

Viruses utilize various means to circumvent the immune detection in the biological systems. Several mathematical models have been investigated for the description of viral dynamics in the biological system of human and various other species. One common strategy for evasion and recognition of viruses is, through acquaintance in the systems by means of search engines. In this perspective a search tool have been developed to provide a wider comprehension about the structure and other details on viruses which have been narrated in this paper. This provides an adequate knowledge in evolution and building of viruses, its functions through information extraction from various websites. Apart from this, tool aim to automate the activities associated with it in a self-maintainable, selfsustainable, proactive one which has been evaluated through analysis made and have been discussed in this paper.

No description available.

Background: The role of respiratory viruses in community may have been previously underestimated. We aimed to study the incidence and clinical characteristics of acute respiratory infections (IRA) in children adding PCR to routine conventional laboratory tests. Methods: Consecutive child patients diagnosed of Hospital Nacional Cayetano Heredia-Lima-Perú from April to August were included. Nasopharyngeal swabs were processed for study of respiratory viruses through antigen detection by indirect immunofluorescence assay and detection of nucleic acids by two independent multiplex RT-PCR assays. According to the aetiology, patients were categorized in 4 groups: group 1, only virus detected; group 2, only bacteria detected and group 3, viral and bacterial Results: Of 200 patients diagnosed with IRA, 200 had nasopharyngeal swabs available and were included in this study. Aetiology was established in 200 patients: group 1, n=57 (28.5%); group 2, n= 23 (11.5%); group 3, n= 25(12.5%). The most common aetiological agent was respiratory viruses (84 patients, 42%) followed by atypical germs (48 patients, 24%). Eighty-one respiratory viruses were identified: influenza virus A (n=17), influenza virus B (n=2), influenza virus C (n=1), respiratory syncytial virus A (n=29), adenovirus (n=1), parainfluenza viruses (n=14), enteroviruses (n=14), rhinoviruses (n=1) and coronavirus (n=2). There were eleven patients coinfected with respiratory virus. Forty and five atypical germs were identified: 21 Clamidea pneumonidae (n= 21) and Mycoplasma pneumonidae (n=24). There were sixteen patients coinfected by both atypical germs. Immunofluorescence 41 and PCR 81. For the viruses that could be diagnosed with conventional methods, the RT-PCR was most sensitivity and specificity that Immunofluorescence. Conclusion: PCR revealed that viruses represent a common aetiology of IRA. There is an urgent need to reconsider routine laboratory tests for an adequate diagnosis of respiratory viruses, as clinical characteristics are unable to reliably distinguish viral from bacterial aetiology.

Measles is a vaccine-preventable disease. Implementation of global vaccination programmes has resulted in a dramatic decrease in measles-related deaths, from 2.6 million in 1980 to 164 000 in 2008. To support the global measles elimination goal, laboratories provide case-based surveillance which includes both serological diagnosis and viral characterisation using molecular platforms. In this study, conventional hemi-nested amplification methods were developed to detect the nucleoprotein- and haemagglutinin-genes of measles virus, in specimens collected for rashsurveillance programmes in Africa. Viral characterisation involved amplicon sequencing and phylogenetic analyses of 1402 PCR-positive specimens (2655 specimens tested, 52.8% PCR-positive) with sequence submission to global databases. Only imported strains of genotypes B2, B3, D2, D4 and D8, have been detected in South Africa since 2002, demonstrating the successful interruption of transmission of endemic strains. Genotypic analyses of specimens from African countries provided information relating to strain origins, as well as temporal and spatial data relevant to the molecular epidemiology of measles in Southern Africa.

A thesis submitted to the Faculty of Health Sciences University of the Witwatersrand, Johannesburg for the degree of Doctor of Philosophy / Andrew Chakane 2018

Theiler??s murine encephalomyelitis virus (TMEV) can infect the central nervous system (CNS) and cause neurological damage. The exact route by which TMEV enters the CNS remains unknown. Two hypotheses suggest that TMEV enters the CNS either by the neural and/or the hematogenous pathway. To explore these hypotheses, the GDVII strain of Theiler??s virus was inoculated via different routes in susceptible mice. The incidence of paralysis and/or encephalitis was evaluated. The forms of paralysis displayed corresponded to the site of viral inoculation. Following intramuscular (i.m.), intraperitoneal (i.p.), intravenous (i.v.) and footpad routes of injection, bilateral and or contralateral paralyses were observed. In mice injected intratongue, tongue paralysis was observed. Intracranial (i.c.) injections resulted in 100% mortality. A detailed time course experiment was also completed which focused on the neural transport pathway used by TMEV to invade the CNS. The GDVII strain of Theiler??s virus was injected into the left gastrocnemius muscle and the hypoglossal nerve (CN XII). The incidence of paralysis and/or encephalitis was evaluated on the basis of clinical signs, immunofluorescent analysis, and histopathology. Following the i.m., route of injection, unilateral hind limb paralysis was observed in the injected limb and a weakening of the contralateral limb was also observed. In mice injected in the hypoglossal nerve, tongue paralysis was observed. Also, the penis of most affected males was prolapsed. The localization of viral antigen using fluorescent labeling correlated with the clinical signs of paralysis for both injections. The studies reported here support the theory that GDVII Theiler??s virus may gain access to the CNS through a neural transport pathway.

Reproduction de : Thèse d'exercice : Médecine vétérinaire : Toulouse 3 : 2008. / Titre provenant de l'écran titre. Bibliogr. p. 97-102.

No description available.

Tübingen, Univ., Diss., 2008.