The extraordinary evolutionary history of the reticuloendotheliosis viruses

The reticuloendotheliosis viruses (REVs) comprise several closely related amphotropic retroviruses isolated from birds. These viruses exhibit several highly unusual characteristics that have not so far been adequately explained, including their extremely close relationship to mammalian retroviruses, and their presence as endogenous sequences within the genomes of certain large DNA viruses. We present evidence for an iatrogenic origin of REVs that accounts for these phenomena. Firstly, we identify endogenous retroviral fossils in mammalian genomes that share a unique recombinant structure with REVs—unequivocally demonstrating that REVs derive directly from mammalian retroviruses. Secondly, through sequencing of archived REV isolates, we confirm that contaminated Plasmodium lophurae stocks have been the source of multiple REV outbreaks in experimentally infected birds. Finally, we show that both phylogenetic and historical evidence support a scenario wherein REVs originated as mammalian retroviruses that were accidentally introduced into avian hosts in the late 1930s, during experimental studies of P. lophurae, and subsequently integrated into the fowlpox virus (FWPV) and gallid herpesvirus type 2 (GHV-2) genomes, generating recombinant DNA viruses that now circulate in wild birds and poultry. Our findings provide a novel perspective on the origin and evolution of REV, and indicate that horizontal gene transfer between virus families can expand the impact of iatrogenic transmission events

Dominance of variant A in Human Herpesvirus 6 viraemia after renal transplantation

<p>Abstract</p> <p>Background</p> <p>Human herpesvirus 6 (HHV-6), mostly variant B reactivation in renal transplant patients has been published by other authors, but the pathogenetic role of HHV-6 variant A has not been clarified. Our aims were to examine the prevalence of HHV-6, to determine the variants, and to investigate the interaction between HHV-6 viraemia, human cytomegalovirus (HCMV) infection and clinical symptoms.</p> <p>Methods</p> <p>Variant-specific HHV-6 nested PCR and quantitative real-time PCR were used to examine blood samples from renal transplant patients and healthy blood donors for the presence and load of HHV-6 DNA and to determine the variants. Active HHV-6 infection was proved by RT-PCR, and active HCMV infection was diagnosed by pp65 antigenaemia test.</p> <p>Results</p> <p>HHV-6 viraemia was significantly more frequent in renal transplant patients compared to healthy blood donors (9/200 vs. 0/200; p = 0.004), while prevalence of HHV-6 latency was not significantly different (13/200 vs. 19/200; p > 0.05). Dominance of variant A was revealed in viraemias (8/9), and the frequency of HHV-6A was significantly higher in active infections compared with latency in renal transplant patients (8/9 vs. 2/13; p = 0.0015). Latency was established predominantly by HHV-6B both in renal transplant patients and in healthy blood donors (11/13 and 18/19). There was no statistical significant difference in occurrence of HCMV and HHV-6 viraemia in renal transplant patients (7/200 vs. 9/200). Statistical analysis did not reveal interaction between HHV-6 viraemia and clinical symptoms in our study.</p> <p>Conclusions</p> <p>Contrary to previous publications HHV-6A viraemia was found to be predominant in renal transplant patients. Frequency of variant A was significantly higher in cases of active infection then in latency.</p

The management of Japanese quail and their use in virological research: A review

Since the domestication of Japanese quail during the last few decades, they are extensively used as table birds and pet birds. These birds, because of their physiological resemblance to chickens, inexpensive maintenance and rapid generation turnover are increasingly used in biomedical research including virology. In the present review the life cycle of birds, care and incubation of eggs, rearing, nutrition and naturally occurring diseases are described. The use of Japanese quail, their embryos and cell cultures derived from them in virological research are also discussed

Preservation of avian cells at sub-zero temperatures

The cryoprotective agents dimethyl sulfoxide (DMSO), glycerol, polyvinylpyrrolidone (PVP) and dextran were evaluated for their ability to protect avian cells during storage at sub-zero temperatures. DMSO was the most effective cryoprotective agent for the short- and long-term storage of avian cells and glycerol was also effective when used at low concentrations. PVP and dextran did not protect avian cells during storage in our experiments. Primary chicken cells and avian cells at higher passage levels were successfully recovered after storage with DMSO for periods ranging from 4 to 12 months. Whole embryos were frozen with varying concentrations of DMSO, and the survival rates and cell yields were determined for chicken embryo fibroblasts (CEF) prepared from the frozen embryos. Frozen embryos did not yield as large a number of cells as the fresh ones, but storage with 25 % DMSO gave over 50% cell yields and survival rates. The ability of frozen CEF and chicken embryo kidney cells (CEK) to support virus growth was also investigated. Assays of infectious laryngotracheitis, Sindbis, fowlpox, Newcastle disease, adeno- and turkey herpes viruses agreed within 0.5 loglo (50% tissue culture infective doses) when conducted in frozen and fresh CEF and CEK

Establishment of a chicken lymphoblastoid cell line infected with reticuloendotheliosis virus

A lymphoblastoid cell line derived from the spleen of a chicken infected with an Australian strain of reticuloendotheliosis virus (REV) and designated RE-LB was established in suspension culture. The presence of REV antigen in the cells was demonstrated by the indirect fluorescent antibody test, while ultrathin sections of the RE-LB line cells revealed C-type particles. Infection of day-old-chickens with the cellular and cell-free culture fluid of the line produced 100 per cent and 50 per cent mortality, repectively. The line is probably transformed because the cells were agglutinated by concanavalin A and grew in soft agar

Outbreak of human metapneumovirus inflection in a residential aged care facility

Summer outbreaks of respiratory illness in residential aged care facilities are uncommonly reported in New South Wales. A respiratory illness outbreak in an aged care facility during January 2008 prompted a response to contain the outbreak by implementing infection control measures, including cohorting of symptomatic residents, cohorting nursing care, closure to new admissions and the use of personal protective equipment by staff. In addition, respiratory tract specimens were collected to determine the causative agent. Human metapneumovirus (hMPV) was detected by polymerase chain reaction assay in 3 specimens with no other respiratory pathogens found. This is the 1st reported outbreak of hMPV in an aged care facility in Australia. hPMV should be considered as the possible cause of outbreaks in aged care facilities when influenza and respiratory syncytial virus have been excluded