The HIV virus

Newly forming HIV virions

This beautiful piece of awesome appears on the cover of the June 2012 edition of PLoS Pathogens and shows “newly forming HIV virions in the leading edge of dynamic filopedia”, as published here.

Specifically, the paper was looking at ways HIV is able to transfer between dendritic and CD4 T immune cells, aiding in the progression of the viral infection.

By using live dynamic imaging of HIV infected dendritic cells, they found that the viral particles actually hijack projections on the surface of the immune cells (filopodia), thereby corrupting the ability of the immune cells to interact.

At the same time, this enables HIV particles to be “launched”, facilitating further infection.

In relation to the above image, what you can see is the incorporation of HIV into dendritic cell filopodia, with HIV particles in white, filopodial networks in red, and the cellular nucleus in blue.

We’re on to you, HIV.

Dengue virus

sciencenote:

Dengue virus (DENV) is a mosquito-borne flavivirus that affects 2.5 billion people worldwide. There are four dengue serotypes (DENV1 to DENV4), and infection with one elicits lifelong immunity to that serotype but offers only transient protection against the other serotypes. Identification of the protective determinants of the human antibody response to DENV is a vital requirement for the design and evaluation of future preventative therapies and treatments. Here, we describe the isolation of a neutralizing antibody from a DENV1-infected patient. The human antibody 14c10 (HM14c10) binds specifically to DENV1. HM14c10 neutralizes the virus principally by blocking virus attachment; at higher concentrations, a post-attachment step can also be inhibited. In vivo studies show that the HM14c10 antibody has antiviral activity at picomolar concentrations. A 7 Å resolution cryoelectron microscopy map of Fab fragments of HM14c10 in a complex with DENV1 shows targeting of a discontinuous epitope that spans the adjacent surface of envelope protein dimers. As found previously, a human antibody specific for the related West Nile virus binds to a similar quaternary structure, suggesting that this could be an immunodominant epitope. These findings provide a structural and molecular context for durable, serotype-specific immunity to DENV infection.

H5N1 Influenza Virus: The answers

The scientific community is abuzz this week, following the publication of a second controversial H5N1 paper that identifies a series of mutations that give the virus the ability to spread through the air.

To bring you up to date on the current status of this potentially deadly virus, Ed Yong at Nature magazine has kindly presented the top five questions regarding H5N1, including:

• Why is it so successful?
• Where is it now?
• How does it kill?
• Will it become transmissible in humans?
• What else could cause a pandemic?

For the answers to these questions and more, head to Nature for the full article.

Deadly genomes: Mapping the size, content, and impact of some of the world’s deadliest infectious agents

See high resolution image here.

Three dimensional structure of the Ebola virus

The causative agent of viral hemorrhagic fever in humans and a potential biological weapon, Ebola virus is presented here in beautiful, three dimensional form.

The Ebola-encoded structures are shown in maroon, while human cells are shown in grey. This model was based on 20 years of virology data, X-ray analysis, and computation biology techniques.

The Diversity of Viruses

Of all the infectious agents, viruses are the most unique and the above image gives a great outline of their diversity.  Responsible for many of the most common and serious human diseases, they remarkably remain metabolically inert and lack the ability to replicate on their own.

Structurally, viruses primarily consist of genetic material in the form of DNA or RNA which is protected by a highly ordered cage of proteins, known as the capsid. Some viruses also contain an additional outer envelope or membrane consisting of lipids, or glycoproteins.

The outer surface of the virus enables it to make contact with the outer membrane of a host cell and facilitates its uptake into the cytoplasm.  Once there, the virus hijacks the host cell’s machinery enable its replication and the production of viral proteins.  Newly replicated viruses are then either released via rupture of the host cell, or the viral genetic material is incorporated into and replicated with the host cell’s genome.

Wild Poliovirus

This is a molecular graphics simulation of the Mahoney strain of wild poliovirus type 1, family Picornaviridae, genus Enterovirus. The capsid, or protein shell, is composed four structural units: VP1 (blue), VP2 (red), VP3 (yellow), and VP4 (green).  The RNA genome (purple) is shown within the capsid.

Viruses of the Picornaviridae family are often implicated in the onset of acute gastroenteritis, a common illness throughout the life of humans and animals.