No abstract

The growth characteristics of four temperature-sensitive or cold-adapted recombinant influenza viruses and eight recombinant influenza viruses derived in other ways, together with the wild-type, parent viruses of these strains, were tested in hamster lungs and turbinates and in embryonated eggs at different temperatures for their replicative ability. The results showed that although the temperature-sensitive and cold-adapted recombinant viruses replicated to considerably lower titres than their wild-type parent virus strains in hamster lung and at 37 degrees C in embryonated eggs, no similar pattern of growth was observed for the group of A/PR 8 and A/Okuda recombinant influenza viruses studied in these systems. The hamster model is not therefore generally applicable as a marker for attenuated influenza virus vaccine strains.

The persistence and extrapulmonary spread of three strains of influenza virus, the mouse neuro-adapted A/NWS virus, the wild-type strain A/Victoria/75, and a recombinant virus RIT4050, bearing surface antigens derived from A/Victoria/75, were studied in both normal and cyclophosphamide-treated CBA mice following either intranasal or intracerebral inoculation. All three viruses showed increased lethality in mice in the presence of cyclophosphamide but exhibited distinctive patterns of replication and spread. The recombinant virus RIT4050 showed a reduced ability to replicate, persist, and spread in CBA mice compared to either A/NWS or A/Victoria/75 viruses, and in general, the A/NWS virus persisted to a greater extent than the A/Victoria/75 virus in both normal and treated mice. However, in the presence of cyclophosphamide, no extrapulmonary spread of A/NWS virus was observed. The reasons for the differences are discussed.

Rotaviruses are the single most important etiologic agents of severe diarrhea of infants and young children worldwide. In the present study, serological detection of rotavirus was done using an enzyme linked immunosorbent assay (ELISA), on 247 stool specimens. These were collected from children with acute diarrhea attending the outpatient clinic of Alexandria University Children's Hospital at El-Shatby, from October 2005 to April 2007. Rotavirus was detected in 33.6% of the collected samples; no specific age group or sex predilection was observed. It was presented with a marked seasonal peak during autumn and winter (58.3% and 40.5%, respectively). Rotavirus was found to be infecting most commonly underweight children (46.9 %) resulting into fluid loss and severe dehydration (80%). Rotavirus acute gastroenteritis was found to be associated with fever (38.8%), vomiting (39.9%), watery stools, and long duration of diarrheal episodes lasting from one up to six days. The appearance of convulsions among rotavirus-positive cases even in the absence of fever (84.6%) was an important finding. Exclusive formula-fed infants appeared to exhibit the highest disease incidence (50%) while exclusive breast-fed infants had a lower incidence level (35.2%) of the disease. The virus was found to be significantly affecting children living in rural areas of Egypt (43.8%) rather than urban ones (26.1%). Environmental factors that were shown to affect the disease incidence include: the presence of impurities in water (41.6%), broken pipes (58.1%) and water tanks (58.7%) at the residence place. On the other hand, neither the kind of water source nor the presence of a sewage-disposal network was significantly related to the disease. Therefore, the study recommended to screen for rotavirus in children with diarrhea in order to avoid the use of unnecessary medications. In addition, encouragement of breast feeding practices and improvement of environmental conditions are important means of prevention of rotavirus infection.