Archive for May 10th, 2013

Cassava Viral Disease Spreads at Alarming Rate

10 May, 2013

See on Scoop.itVirology News

Scientists say a disease destroying entire crops of cassava has spread out of East Africa into the heart of the continent, is attacking plants as far south as Angola and now threatens to move west into Nigeria, the world’s biggest producer of the potato-like root that helps feed 500 million Africans.

Photo: healthy cassava, Ed Rybicki, western Kenya, 1998

Ed Rybicki‘s insight:

This is a really big deal – and it comes just 15 years or so after another cassava scourge, caused by a recombinant begomovirus, swept out of Uganda.  That one was credited with helping to kill over 20 000 people, due to starvation and assocaited morbidity.  This one – Cassava brown streak virus, or CBSV – is a filamentous ssRNA potyvirus (genus Ipomovirus, family Potyviridae), spread by whiteflies ratehr than the usual potyvirus vector (aphids).

 

Gerhard Pietersen and I noted in 1999 that CBSV was an emerging virus, but not a serious problem (Adv Virus Res, 53, 127-175, 1999).

It has obviously emerged, and is.  Now to deal with it!

See on www.sci-tech-today.com

Recombinant Monovalent Llama-Derived Antibody Fragments (VHH) to Rotavirus VP6 Protect Neonatal Gnotobiotic Piglets against Human Rotavirus-Induced Diarrhea

10 May, 2013

See on Scoop.itVirology News

This study shows that the oral administration of rotavirus VP6-VHH nanoAb is a broadly reactive and effective treatment against rotavirus-induced diarrhea in neonatal pigs. Our findings highlight the potential value of a broad neutralizing VP6-specific VHH nanoAb as a treatment that can complement or be used as an alternative to the current strain-specific RVA vaccines. Nanobodies could also be scaled-up to develop pediatric medication or functional food like infant milk formulas that might help treat RVA diarrhea.

Ed Rybicki‘s insight:

Always nice to Scoop a paper from a co-author, in this case Andres Wigdorovitz and friends.  Nice work, too – shows that rotavirus VP6 is a useful recombinant protein target for use as a vaccine, given that llama single-chain Abs specific to it can protect.  But why not make them in plants, Andres??

See on www.plospathogens.org

Antigenic Drift of the Pandemic 2009 A(H1N1) Influenza Virus in a Ferret Model

10 May, 2013

See on Scoop.itVirology News

Infection with influenza virus leads to significant morbidity and mortality. Annual vaccination may prevent subsequent disease by inducing neutralizing antibodies to currently circulating strains in the human population. To escape this antibody response, influenza A viruses undergo continuous genetic variation as they replicate, enabling viruses with advantageous antigenic mutations to spread and cause disease in naïve or previously immune or vaccinated individuals. To date, the 2009 pandemic virus (A(H1N1)pdm09) has not undergone significant antigenic drift, with the result that the vaccine remains well-matched and should provide good protection to A(H1N1)pdm09 circulating viruses. In this study, we induced antigenic drift in an A(H1N1)pdm09 virus in the ferret model. A single amino acid mutation emerged in the dominant surface glycoprotein, hemagglutinin, which had a multifaceted effect, altering both antigenicity and virus receptor specificity. The mutant virus could not be isolated using routine cell culture methods without the virus acquiring additional amino acid changes, yet was fit in vivo. The implications for surveillance of circulating influenza virus are significant as current assays commonly used to assess vaccine mismatch, as well as to produce isolates for vaccine manufacture, are biased against identification of viruses containing only this mutation.

 

Ed Rybicki‘s insight:

There is a rather disturbing result in this paper: that is, that the mutation in the H1N1 HA that emerged in serial ferret transfers that was responsible for antigenic drift, resulted in a virus that could NOT be cultured by routine methods despite being quite happy in ferrets.  In fact, adapting the virus to culture meant it accumulated MORE mutations, meaning the thing they got out by "current assays" was NOT the same thing that was causing disease.

 

This is worrying for a number of reasons, not least of which is that informed decisions on probable vaccine efficiacy are made as a result of such assays – and the vaccines themselves, in some cases.  And if what these decisions are based on is incorrect…?

 

Time for some better science here, people – like next-gen sequencing rather than isolation as a measure of what is causing disease!

See on www.plospathogens.org