HOMO SAPIENS DISEASES - SUBCELLULAR LIFE FORMS
(see also Physiology of subcellular life forms and Antimicrobials for viruses)

Table of contents :


  • Viruses => viroses
  • Generalities for viroses
    Web resources


    Our guts are teeming with 1,200 different viruses, > 50% of which are unknown to science : most are bacteriophagesref. Some 99% of the world's bugs cannot be grown, or therefore identified, in the laboratory

    Viruses

    One strategy used by human alpha- and gammaherpesviruses to facilitate such competition is to shut off the expression of host genes located in the nuclear genome. Host shutoff involves inhibition of host gene transcription, alterations in mRNA processing, and the loss of cytoplasmic mRNAs. Altogether, these effects help redirect the cellular gene expression machinery toward the expression of viral genes. Interestingly, herpes simplex virus type 1 (HSV-1), HSV-2, and Epstein-Barr virus (EBV) have also evolved mechanisms to disrupt the expression of genes located in the host mitochondrial genome by degrading mitochondrial DNA (mtDNA)ref
    There are 3 subfamilies :
    Epidemiology : identified in 2011 in a skin swab sample from a healthy donor, similar to the chicken anemia virus (CAV), the only previously known member of the Gyrovirus genus. In particular, this virus encodes an homolog of the CAV apoptin, a protein that selectively induces apoptosis in cancer cells. By PCR screening, HGyV was found in 5 of 115 other non-lesional skin specimens, but in none of 92 bronchoalveolar lavages or nasopharyngeal aspirates and in none of 92 fecal samplesref.
    Epidemiology : isolated in 1999 and 2006 from febrile patients in the cities of Iquitos and Yurimaguas in Peru. The geographic distance between the 2 cases suggests that the Itaya virus could be widely distributed throughout the Amazon basin in northeastern Peruref
    Epidemiology : was first isolated in Nigeria in 1966 during surveys of livestock, Culicoides midges, and mosquitoes, SHUV also once was isolated from a febrile childref1, ref2. SHUV recently was identified as a previously undetected cause of neurologic disease in horses in southern Africaref and veterinarians in South Africaref and is thus of interest in comparison to WNV.
    Epidemiology : in 2009 >150 human infections in 16 Chinese provinces and to have an associated death rate of ≈12%ref1, ref2. Fatal SFTSV infections were reported in humans in Japan in 2012ref and South Korea in 2012ref.
    Transmission
    : isolated from blood of 2 patients and from Haemaphysalis ticks (Anaplasma phagocytophilum) collected from dogs. Isolation of the virus from ticks does not prove their vector capacity, nor from dogs indicates that they are competent sources of infectious blood meals for arthropod vectors, but these findings do indicate that laboratory susceptibility and transmission experiments are worth doingref1, ref2

    Epidemiology : in June 2009, in northwestern Missouri, United States, 2 men from 2 geographically distant farms were hospitalized for fever, fatigue, diarrhea, thrombocytopenia, and leukopenia. Both men had been bitten by ticks 5–7 days before the onset of symptoms. A virus was isolated from the leukocytes of each patient and later identified as a novel phlebovirus by next-generation sequencing. The 2 viruses were highly related (98%, 95%, and 99% sequence identity for the small, medium, and large viral genome segments, respectively), indicating that the men were independently infected with the same virusref.
    • Hunter Island Group virus (HIGV)
    Epidemiology : isolated retrospectively in 2014 during the investigation of a disease outbreak among shy albatrosses in Tasmania in 2002ref
    Transmission : ticks (Ixodes eudyptidis)