Researchers Use Virus
That Only Hits Insects, Has No Effect On Humans
Scientists have
developed the first vaccine for chikungunya fever, made from an insectspecific
virus that does not have any effect on people and is thus safe and effective.
The vaccine quickly
produces a strong immune defence and completely protects mice and nonhuman
primates from disease when exposed to the chikungunya virus, researchers said.
“This vaccine offers
efficient, safe and affordable protection against chikungunya and builds the
foundation for using viruses that only infect insects to develop vaccines
against other insectborne diseases,“ said Scott Weaver, professor at the
University of Texas Medical Branch at Galveston (UTMB) in the US. Chikungunya
is a mosquitoborne virus that causes a disease characterised by fever and severe
joint pain, and may trigger headaches, muscle pain, joint swelling, or rashes.
Some patients feel better within a week, but many develop longer-term joint
pain that can last up to years. Death is rare but can occur.
Traditionally , vaccine
development involves trade-offs between how quickly the vaccine works and its
safety. Live-attenuated vaccines that are made from weakened versions of a live
pathogen typically offer rapid and durable immunity but reduced safety . On the
other hand, the inability of inactivated vaccines to replicate enhances safety
at the expense of effectiveness, often requiring several doses and boosters to
work properly. There may be a risk of disease with both types of vaccines.
To overcome these
trade-offs, the researchers used the Eilat virus as a vaccine platform since it
only infects insects and has no impact on people. The UTMB researchers used an
Eilat virus clone to design a hybrid vaccine containing chikungunya structural
proteins. The vaccine was found to be structurally identical to the natural
chikungunya virus.The difference is that although the hybrid virus replicates
very well in mosquito cells, it cannot replicate in mammals.
Within four days of a
single dose, the EilatChikungunya candidate vaccine induced neutralising antibodies
that lasted for more than 290 days. The antibodies provided complete protection
against chikungunya in two different mouse models. In nonhuman primates,
EilatChikungunya elicited rapid and robust immunity -there was neither evidence
of the virus in the blood nor signs of illness, the researchers said.
Source: The Times Of India-21st-December-2016
