RNA silencing and viral disease induction in plants

RNA silencing plays a critical role in plant resistance against viruses, with multiple silencing factors participating in antiviral defense. Both RNA and DNA viruses are targeted by the small RNA-directed RNA degradation pathway, with DNA viruses being also targeted by RNA-directed DNA methylation. To evade RNA silencing, plant viruses have evolved a variety of counter-defense mechanisms such as expressing RNA-silencing suppressors or adopting silencing-resistant RNA structures. This constant defense–counter defense arms race is likely to have played a major role in defining viral host specificity and in shaping viral and possibly host genomes. Recent studies have provided evidence that RNA silencing also plays a direct role in viral disease induction in plants, with viral RNA-silencing suppressors and viral siRNAs as potentially the dominant players in viral pathogenicity. However, questions remain as to whether RNA silencing is the principal mediator of viral pathogenicity or if other RNA-silencing-independent mechanisms also account for viral disease induction. RNA silencing has been exploited as a powerful tool for engineering virus resistance in plants as well as in animals. Further understanding of the role of RNA silencing in plant–virus interactions and viral symptom induction is likely to result in novel anti-viral strategies in both plants and animals.

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The Diagnosis of Viral Disease by Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010005398x ◽

1982 ◽

Vol 40 ◽

pp. 270-273

Author(s):

William B. McCombs ◽

Cameron E. McCoy

Keyword(s):

Electron Microscopy ◽

Hospital Stay ◽

Viral Infections ◽

Medical Profession ◽

Bacterial Pathogens ◽

Viral Disease ◽

Viral Pathogens ◽

Academic Interest ◽

The Past

Recent years have brought a reversal in the attitude of the medical profession toward the diagnosis of viral infections. Identification of bacterial pathogens was formerly thought to be faster than identification of viral pathogens. Viral identification was dismissed as being of academic interest or for confirming the presence of an epidemic, because the patient would recover or die before this could be accomplished. In the past 10 years, the goal of virologists has been to present the clinician with a viral identification in a matter of hours. This fast diagnosis has the potential for shortening the patient's hospital stay and preventing the administering of toxic and/or expensive antibiotics of no benefit to the patient.

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Effect of acid deposition on trichome morphology and dogwood anthracnose biology

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100124604 ◽

1992 ◽

Vol 50 (1) ◽

pp. 840-841

Author(s):

Kyle T. Thornham ◽

R. Jay Stipes ◽

Randolph L. Grayson

Keyword(s):

Acid Deposition ◽

Disease Incidence ◽

Natural Populations ◽

Tree Disease ◽

Flowering Dogwood ◽

Discula Destructiva ◽

Disease Induction ◽

Dogwood Anthracnose ◽

Trichome Morphology ◽

Precipitation Events

Dogwood anthracnose, caused by Discula destructiva (1), is another new catastrophic tree disease that has ravaged natural populations of the flowering dogwood (Cornus florida) in the Appalachians over the past 15 years, and the epidemic is prognosticated to continue (2). An estimated 9.5 million acres have been affected, primarily in the Appalachian Mountains, from VA southwards, alone, and an estimated 50% of all dogwoods in PA have been killed. Since acid deposition has been linked experimentally with disease induction, and since the disease incidence and severity are more pronounced at higher elevations where lower pH precipitation events occur, we investigated the effect of acidic foliar sprays on moiphologic changes in the foliar cuticle and trichomes (3), the initial sites of infection and foci of Discula sporulation.

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A rapid method for the direct identification of paramyxovirus in canine CSF by ultracentrifugation and negative staining as a rule out for distemper

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100160522 ◽

1990 ◽

Vol 48 (3) ◽

pp. 594-595

Author(s):

W.L. Steffens ◽

M.B. Ard ◽

C.E. Greene ◽

A. Jaggy

Keyword(s):

Subacute Sclerosing Panencephalitis ◽

Clinical Signs ◽

Viral Disease ◽

Etiologic Agent ◽

Mucosal Inflammation ◽

Worldwide Distribution ◽

Negative Stain ◽

Viral Particles ◽

Systemic Manifestations ◽

Rule Out

Canine distemper is a multisystemic contagious viral disease having a worldwide distribution, a high mortality rate, and significant central neurologic system (CNS) complications. In its systemic manifestations, it is often presumptively diagnosed on the basis of clinical signs and history. Few definitive antemortem diagnostic tests exist, and most are limited to the detection of viral antigen by immunofluorescence techniques on tissues or cytologic specimens or high immunoglobulin levels in CSF (cerebrospinal fluid). Diagnosis of CNS distemper is often unreliable due to the relatively low cell count in CSF (<50 cells/μl) and the binding of blocking immunoglobulins in CSF to cell surfaces. A more reliable and definitive test might be possible utilizing direct morphologic detection of the etiologic agent. Distemper is the canine equivalent of human measles, in that both involve a closely related member of the Paramyxoviridae, both produce mucosal inflammation, and may produce CNS complications. In humans, diagnosis of measles-induced subacute sclerosing panencephalitis is through negative stain identification of whole or incomplete viral particles in patient CSF.

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Modern aspects of tactics in the genital herpes viral infection (literature review)

GYNECOLOGY ◽

10.26442/2079-5696_2018.2.67-73 ◽

2018 ◽

Vol 20 (2) ◽

pp. 67-73

Author(s):

T Yu Pestrikova ◽

E A Yurasova ◽

I V Yurasov ◽

A V Kotelnikova

Keyword(s):

Literature Review ◽

Viral Infection ◽

Genital Herpes ◽

Fetal Death ◽

Malignant Tumors ◽

Adult Population ◽

Viral Disease ◽

Intrauterine Fetal Death ◽

Complicated Course ◽

Simplex Virus

Genital herpes affects all population groups. 98% of the adult population worldwide have antibodies to the herpes simplex virus (HSV-1 or 2). This viral infection is a significant medical and social problem. HSV can lead to a complicated course of pregnancy, causing miscarriages, premature birth, intrauterine fetal death, systemic viral disease in newborns. There is evidence that HSV has a connection with malignant tumors of the prostate and cervix, contributing to their development. This literature review contains modern aspects of epidemiology, etiology, pathogenesis, clinic, diagnosis, treatment of genital herpes, including its recurring forms with valacyclovir (Valvir). Indications for hospitalization of patients with genital herpes were noted and the prognosis of this pathology was determined. The tactics of managing pregnant women with this pathology is presented.

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