Saturday, July 13, 2024

How Is Herpes Spread From Host To Host

I Had Lesions When I Was Evaluated But My Culture Was Negative Does This Mean That I Dont Have Herpes

Herpes (oral & genital) – causes, symptoms, diagnosis, treatment, pathology

Not necessarily. Although lesions can be caused by something other than herpes, false negative herpes tests can occur if the samples are not taken appropriately, if there is a long transport time between the clinic and the laboratory, or if cultures were taken late in the course of the lesions. Lesions that occur early in the course of a herpes outbreak are much more likely to have positive cultures than cultures taken after the lesions crust over.

Evasion Of T Cells And Dendritic Cells

Suppress T cell and dendritic cell recruitment

T cells are a major component of the immune response to foreign invaders, like HSV. They activate B cells to make antibodies, destroy infected cells, and release cytokines to recruit other immune cells. HSV has developed many strategies to interfere with immune functions associated with the T cell response during a lytic cycle, including T cell recruitment, activation, receptor signaling, and the interferon response, to evade immune detection. For there to be a meaningful T cell response, T cells must be recruited to the infection site. To combat this in viral encephalitis, HSV produces UL13 kinase which downregulates the expression of the chemokine CXCL9 which, along with CXCL10, attracts CD8+ T cells against HSV specifically to destroy the virally infected cells . This allows the virus to continue to reside in the central nervous system and cause encephalitis. HSV also decreases the number of dendritic cells recruited to the infected tissue, thereby decreasing the opportunity for interaction with T cells. This is done by modifying the chemokine receptor CCR7 on the dendritic cells surface so it can no longer bind the chemokine sent out to recruit immune cells to the infected cells, resulting in less dendritic cells in the infected tissues and less activation of T cells .

Inhibit T cell activation

Interrupt T cell signaling

Can Herpes Be Spread Without Symptoms

Most people get herpes from someone who doesnt have any sores. Sometimes those who know they are infected spread the virus between outbreaks when no signs or symptoms are present. This is called asymptomatic transmission. It may live in your body for years without causing any symptoms, so its really hard to know for sure when and how you got it. Thats why so many people have herpes its a pretty sneaky infection.

Because the virus dies quickly outside the body, you cant get herpes from hugging, holding hands, coughing, sneezing, or sitting on toilet seats.

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Rna Sequencing And Analysis

Total RNA from the large intestine musculara was isolated using Trizol® and further purified using the RNeasy RNA isolation kit both according to the manufacturer’s instructions. Total RNA from the lumbosacral DRG was isolated using the RNeasy RNA isolation kit . Samples were further processed and sequenced at the Yale Center for Genome Analysis. High quality samples with a RIN score of at least 7.0 were sequenced with a 150 bp paired end read using an Illumina 2500 HiSeq sequencer. Raw sequence reads were trimmed of sequencing adaptors and low quality regions by btrim . The trimmed reads were mapped to mouse genome by tophat2 and the counts of reads for each gene were based on Ensembl annotation . After the counts were collected, the differential expression analysis was done by DEseq2 , which calculated the adjusted p-values. Differentially expressed genes with at least a 2-fold difference in expression and an adjusted p-value < 0.05 were analyzed using the Ingenuity Pathways Analysis . Volcano plots were constructed using ggplot2 in R with additional editing and annotating using Adobe Illustrator. For HSV-1 genes, the trimmed reads were mapped to Human herpesvirus 1 genome by bowtie2 . The differential expression analysis was done by DEseq2 using normalization factors from host RNA-Seq data for each sample. The Circos plot was generated as previously described and further edited and annotated using Adobe Illustrator. All processed

Researchers Identify How Herpes Virus Infects Host Cells

DNA Viruses in Eukaryotes

Virginia Commonwealth University researchers have uncovered new information about how the herpes simplex virus takes control of the host cell, setting the stage for the development of antiviral drugs that serve to fight herpes infections.

In the United States, the herpes simplex virus, or HSV, is common and can cause symptoms on the mouth or genitals in the form of cold sores or fever blisters. The virus is spread through close contact with an infected person. In rare cases, transmission of the virus can occur between mother and newborn at birth. Under these circumstances, HSV can cause devastating infections of newborns, including fatal encephalitis or inflammation of the brain.

Anthony V. Nicola, Ph.D., associate professor in the Department of Microbiology and Immunology in the VCU School of Medicine, and Mark G. Delboy, a predoctoral candidate in Nicola’s laboratory who led the study, report that HSV takes complete control of normal cell function, or parasitizes, to infect host cells.

Specifically, they found that HSV requires the proteasome for entry into target cells. The proteasome is a large enzyme complex in all cells that is essential for normal cellular functions. The findings are published in the April issue of the Journal of Virology. Additionally, the research paper is featured by the editors of the journal in the Spotlight column as an article of significant interest.

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Molecular Mechanisms Of Infection

FIGURE 1: Schematic of HSV-1/HSV-2 lytic infection. The HSV-1/HSV-2 virion recognizes and attaches to the heparan sulfate proteoglycan via glycoproteins on the viral envelope. By a process called âsurfingâ, the virus particles can travel along filopodia-like membrane extensions to reach the surface of the cell. On the surface of the cell, viral capsid penetration can occur by fusion of envelop with the plasma membrane , or alternatively by endocytosis of enveloped virions with eventual fusion of the envelope with a vesicular membrane . In either case, gD on the virus envelope is required via its interaction with one of the receptors : herpesvirus entry mediator or nectin-1 and-2. In the cytoplasm, the capsid travels to the nucleus where the viral DNA is released. Multiple rounds of replication result in multiple copies of viral DNA and other components that get packaged and assembled in the nucleus. During egress, the newly assembled capsid gets its primary envelope at the peri-nuclear membrane, which is lost during egress from the outer nuclear membrane. Naked capsid travels through the cytoplasm where it receives the tegument and the viral envelope . Heparanase is an enzyme that was recently described in aiding viral egress. The enzyme cleaves of cell surface heparan sulfate which clears the path for the virus to exit the cell.

TABLE 1. List of HSV glycoproteins and their reported functions.

Viral Attachment To Cells

The initial binding of virus to cells is mediated through association of viral glycoprotein gB and/or gC with HS proteoglycans s present on the cell surface. Although gC is not required for entry, gC-deficient virions display decreased overall binding to cell surfaces . gC makes the first contact with HSPGs on the cell surface, but in the absence of gC, gB can take over this function.

Efforts to further understand the viral attachment process recently led to the development of a potential therapeutic consisting of zinc oxide tetrapods. These filopodia-like nanostructures effectively increase the surface area of negatively charged molecules, thereby mimicking the overall negative charge of HS to bind up positively charged viral attachment glycoproteins and decrease cellâvirus interactions. These compounds have been shown to be effective in diminishing infectivity of both HSV-1 and HSV-2 in in vitro and in vivo models of infection. Trapping viral particles in this way to hamper initial infection and prevent cell-to-cell spread could prove a valuable prophylactic and therapeutic in humans.

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Viral Binding To Filopodia

Although the virus binding to cells results from the interaction of gC and/or gB with heparan sulfate , where on the cell this binding can occur the earliest has only recently been elucidated. In human conjunctival epithelial cells, virions were observed attaching to filopodia-like membrane protrusions . It was also observed that virus attachment to filopodia was followed by unilateral movement of the virions towards the cell body. Staining of many natural target cells with anti-HSV receptor antibodies indicated expression of HS but not other entry receptors. Nectin-1 expression, for example, was limited to cell bodies with no detectable expression on filopodia . The phenomenon of extracellular HSV-1 moving unilaterally towards the cell body on filopodia has also been observed in retinal pigment epithelial and P19N neural cells . A similar phenomenon for the transport of extracellular virus particles, termed âviral surfingâ, has been seen with other viruses, such as retroviruses and human papillomavirus type-16 . Surfing is also shared by many additional herpesviruses including cytomegalovirus and human herpesvirus-8 .

Herpes Simplex Virus Exploits The Microfilaments And The Microtubules For Retrograde/anterograde Transport

Herpes simplex (Cold sore): All you need to know

Prior to HSV penetration in the cell, the virus comes across the actin filaments lying toward the cytosolic side of the cell membrane and those which are bound to the surface receptors. When HSV-1 gD interacts with the nectin-1 on the cell surface, the Rho GTPase signaling is activated, which further causes the rearrangement of the actin connected to them . Even during the HSV egress process, the interaction of non-muscle myosin IIA with VP22, which is an HSV tegument protein, is vital for the virions that leave the cell to enter into the extracellular milieu . After successful entry into the cells, the microfilaments, along with the motor protein dynein, assist the HSV from the membrane to the nucleus. As reviewed by Wu et al. , when HSV needs to spread itself to the other host cells, it utilizes the US3 protein kinase to phosphorylate RhoA to rearrange the actin microfilaments and promote the breakdown of the actin stress fibers .

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Can Genital Herpes Be Treated

Your physician can prescribe different medications to help reduce your symptoms and speed up the healing of an outbreak. These medicines work best when you start them soon after an outbreak occurs.

To reduce pain during an outbreak:

  • Sit in warm water in a portable bath or bathtub for about 20 minutes. Avoid bubble baths.
  • Keep your genital area clean and dry, and avoid tight clothes.
  • Take over-the-counter medications, such as acetaminophen or ibuprofen. Avoid aspirin.

Let your physician know if you are worried about your genital herpes. He or she can recommend a support group to help you cope with the virus.

If Someone With Herpes Has No Sores Can It Still Be Passed On

If someone has herpes but no sores, can it still be passed on to another person? Spence*

Yes. Even when no sores are present, the herpes is still active in the body and can spread to others.

If you or your partner has herpes, reduce the risk of spread by:

  • using a condom every time you have sex . The herpes virus can live outside of the area that a condom covers, though, so a condom may not always prevent the spread.
  • avoiding sex during outbreaks
  • making sure the infected person takes antiviral medicine every day as prescribed by the health care provider

The only way to completely prevent herpes and other STDs is to not have sex .

  • *Names have been changed to protect user privacy.

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Ptp1b Is Not The Target Of Salubrinal

The small increase in cell fusion observed when infected knockout cells were treated with salubrinal suggested that the cellular target of this drug might still be present. If PTP1B is not the target, then eIF2 should be phosphorylated to the same extent in response to salubrinal in both MEF lines. For this experiment uninfected cells were used, and these were treated with DMSO, salubrinal, or thapsigargin, which is a well-known inducer of ER stress . The basal level of eIF2 phosphorylation was higher for the knockout cell line , but this was expected since PTP1B is needed to fully shut down the eIF2 kinase PERK . Thapsigargin-induced stress pushed both cell lines into states with equally high levels of phosphorylation, and these levels were matched by salubrinal treatment . Thus, PTP1B seems unlikely to be the target of salubrinal.

Viral Glycoproteins & Membrane Fusion

Labial and Genital Herpes

Fusion of the viral envelope with the plasma membrane is a pH-independent process that requires gB, gD, gH and gL, along with cellular receptors for gD, such as nectin-1, herpes virus entry mediator or 3-O-sulfated HS . gD binding to one of its receptors triggers a conformational change in this glycoproteinâs structure that drives recruitment of a fusion complex including glycoproteins gB, gH and gL. Ultimately this fusion complex results in merging of the lipid bilayers and content mixing with eventual release of the viral nucleocapsid and tegument proteins into the host cytoplasm. Much of the work in recent years has aimed to understand the mechanism of interactions between these glycoproteins and elucidate the steps required for successful fusion of the viral envelope with the plasma membrane.

Molecular interactions mediating HSV entry

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Apoptosis Detection By Flow Cytometry

Optn+/+ and Optn/ HeLa cells were infected with HSV-1 at 0.1 MOI and harvested at 24 hpi. FITC Annexin V/Dead Cell Apoptosis Kit was used to detect apoptosis. As per the manufacturer protocol the sample pellets were washed with cold PBS and then suspended in 1x annexin binding buffer. The suspension was mixed with 5µL FITC Annexin V and 1µL of a propidium iodide solution for 15min in the cold. The mixture was diluted with 1X annexin binding buffer. Further flow cytometry was used to analyze the staining for Annexin V and propidium iodide. Flow data was analyzed using FlowJo software .

Additional Receptors For Hsv Entry

A few cell surface molecules have been implicated as putative HSV-1 gH receptors. These include B5 and αvβ3 integrins . Expression cloning in porcine kidney cells resistant for HSV-1 entry has led to the discovery of B5, a type-2 membrane protein containing an extracellular heptad repeat potentially capable of forming an α-helix for coiled coils . Such structures may facilitate membrane fusion by interacting with viral proteins containing α-helices. A synthetic peptide identical to the heptad repeat region blocks HSV infection of B5-expressing porcine cells and human HEp-2 cells suggesting a possible role for B5 in HSV-1 entry. Since gH also contains an α-helix, it is speculated that it may be a ligand for B5 . No direct interaction between B5 and gH has been demonstrated thus far. In contrast, in a separate study, a soluble form of gH-gL heterodimer was found to specifically bind cells expressing αvβ3 integrins but effect of this interaction on HSV-1 entry has remain elusive . The binding appears to be highly specific since it can be prevented by mutating a potential integrin-binding motif, Arg-Gly-Asp , in gH. Again, more work is needed to determine and establish the significance of potential gH receptors.

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Robust Viral Gene Transcription In The Intestinal Musculara But Not The Drg

Our findings suggested that enteric neurons are susceptible to damage and elimination during an HSV-1 infection . In contrast, sensory DRG neurons are resistant to viral-induced cell death and are not eliminated by HSV infection or cytotoxic T cell infiltration . This raised the intriguing possibility that there are tissue-specific strategies that mitigate neuronal damage in the DRG but are absent in the ENS. To better understand these underlying differences, we preformed RNA sequencing analysis on the DRG and the large intestine musculara containing the ENS at 6 days post HSV-1 infection. To analyze the viral transcriptome, sequenced reads from each tissue were first mapped to the human herpesvirus 1 genome . The number of reads mapping to each nucleotide position are displayed as a Circos plot . Robust and complete viral transcription through all known HSV-1 coding regions was observed in the large intestine musculara of mice with virus-induced megacolon . However, sequence analysis of the infected DRGs revealed that viral transcription through multiple coding regions was less robust or, in some cases, undetectable . Furthermore, when compared to mock levels, approximately half of the beta and gamma genes failed to reach statistical significance in the DRG , whereas all HSV-1 genes were significantly expressed in the large intestine musculara . These data indicate that HSV-1 transcription and replication is restricted in sensory but not enteric neurons.

What Does Genital Herpes Look Like

How Do I even BEGIN to Explain Herpes?

While some people with genital herpes will never have any symptoms, other people can develop symptoms within a few weeks of being infected.

Often, before the lesions appear, patients describe a prodrome, characterized by a tingling or burning sensation in the area where the lesions will develop that can be noticed during urination, along with itching or discomfort in the genital area.

You can also have the following symptoms:

  • Blisters on the mouth or lips
  • Fever, headache or pain in the joints
  • Trouble urinating

The symptoms of genital herpes often go away and come back as recurring outbreaks. For most people, the first outbreak is the worst, and can last from two to three weeks. Future flare-ups are often less severe and do not last as long. Still, some people shed the virus regularly. The following triggers can make outbreaks more likely to occur:

Recurrent genital herpes is most common in the first year after the initial infection and decreases as time goes on.

In many cases, anti-herpes medicine can help patients. When a person experiences a prodrome and suspects a recurrence is going to happen, they begin taking anti-herpes medications that lessen symptoms and shorten the time of the outbreak.

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