Amid increasing speculation that the H1N1 (swine flu) virus is likely to disappear over the summer months only to return in the next flu season, various groups of US researchers are working on a faster way to detect and attack it.

In what has been described as a “multi-pronged” attack comprising a diagnostic and alternative vaccine method, scientists at Emory University, in Altlanta, Georgia, are collaborating with various other institutions to develop a new way of making targeted monoclonal antibodies plus a temporary therapy against H1N1.

The new method will rapidly reproduce antibodies taken from a small amount of blood from people infected with the flu virus and targeted against H1N1. These antibodies could then be used to detect or attack the virus.

In one project, with early results published last year in Nature, researchers from Emory University School of Medicine in and Oklahoma Medical Research Foundation, found they could make high-affinity monoclonal antibodies against influenza virus a month after vaccinating human volunteers.

Dr Rafi Ahmed, director of the Emory Vaccine Center and a Georgia Research Alliance Eminent Scholar said at the time:

“This method could find broad application towards almost any infectious disease.”

For example, the method could help doctors quickly make human antibodies against a pandemic flu strain as a stop gap therapy, or to protect people against infection, said the researchers.

The researchers also found a solution to a thorny problem in vaccination research: the phenomenon called “original antigenic sin”, where making a person immune to a certain strain might mean they have a weakened response against a related strain.

But they found that the B cells, the white blood cells that make the antibodies, were able to target the new virus, even though the immune system had seen related viruses before.

The researchers concluded that original antigenic sin was rare in healthy adults receiving influenza vaccination.

The current methods used for making monoclonal antibodies take a long time. You can either sift through human B cells and look for ones that will make the right antibodies or you can vaccinate mice and “humanize” the mouse antibodies.

But Emory and University of Oklahoma researchers made flu antibodies by isolating antibody-secreting cells (plasma cells) from the blood of volunteers a week after they were vaccinated. They then cloned the antibody genes from these antibody-secreting cells.

Ahmed explained that there was a small window of opportunity when the cells that make the high quality antibodies are in the blood.

“They disappear from the blood afterwards, but at a certain point, most of the antibody-secreting cells are making antibody specific for flu virus,” he explained.

In a more recent study, published in Nature Protocols, the researchers, together with colleagues at Chicago University, described how they developed a protocol for the production of antigen-specific human monoclonal antibodies (hmAbs).

The authors wrote that the protocol can be completed with as little as 20 ml of human blood and in as little as 28 days when optimal.

The new approach is more efficient, and although “dependent on having an ongoing immune response, the approach described herein can be used to rapidly generate numerous antigen-specific hmAbs in a short time,” they concluded.

Dr David S Stephens, vice president for research in Emory’s Woodruff Health Sciences Center said they had some of the world’s “leading groups of infectious disease experts, vaccine scientists, immunologists and microbiologists”.

Emory scientists are also working with colleagues at the US Centers for Disease Control and Prevention (CDC) to develop a quicker and more efficient way of developing flu vaccine.

They are using virus-like particles (VLPs) rather than the current method that involves growing the vaccine in chicken eggs.

VLPs are empty shells that look like viruses. They are made of viral proteins but they don’t have viral nucleic acid, so they can’t reproduce.

The researchers published a paper in PLoS One on 2 March about the effectiveness of the VLP vaccine in mice. They found that:

“VLPs developed high levels of H5N1 specific antibodies and were 100% protected against a high dose of homologous H5N1 virus infection at 30 weeks after immunization.”

Stephens explained that scientists were coming together from the Emory Vaccine Center, the Yerkes National Primate Research Center, Emory University School of Medicine and the University of Georgia to make a significant contribution to the national effort against H1N1 through groundbreaking research and discoveries.

As well as working toward a new way to quickly make monoclonal antibodies against H1N1, scientists at Emory’s flu research center are involved in other important projects, including:

  • Finding out how H1N1 gets into cells and spreads.
  • Discovering how that process might be interrupted.
  • Determining whether having been exposed to other flu viruses helps or hinders immune response to the new H1N1.
  • Assessing any pre-existing immunity to H1N1 in different age groups.
  • Studying how infected patients recover.
  • Beginning the initial stages of a new vaccine.

Meanwhile, scientists at the University of Georgia (UGA) are working out how the H1N1 spreads among animals. They are also looking into how it gets into human airway cells, developing diagnostic tests to tell different virus strains apart, evaluating how stable the virus is, and testing vaccines and anti-viral drugs against H1N1.

Dr Richard Compans, director of the Emory-UGA center said they were proud to be helping the national effort against H1N1 and that working with Emory, the UGA expertise in animal pathology is a strong combination for studying crossover viruses such as the “swine flu”.

“We expect to make significant contributions to this national research effort,” said Compans.

“Rapid generation of fully human monoclonal antibodies specific to a vaccinating antigen.”
Kenneth Smith, Lori Garman, Jens Wrammert, Nai-Ying Zheng, J Donald Capra, Rafi Ahmed, Patrick C Wilson.
Nature Protocols 4, 372 -384 (26 February 2009).
doi:10.1038/nprot.2009.3 Protocol

“Rapid cloning of high-affinity human monoclonal antibodies against influenza virus.”
Jens Wrammert, Kenneth Smith, Joe Miller, William A. Langley, Kenneth Kokko, Christian Larsen, Nai-Ying Zheng, Israel Mays, Lori Garman, Christina Helms, et al.
Nature 453, 667- 671 (30 April 2008).
doi:10.1038/nature06890 Letter

” Induction of Long-Term Protective Immune Responses by Influenza H5N1 Virus-Like Particles..”
Kang S-M, Yoo D-G, Lipatov AS, Song J-M, Davis CT, et al.
PLoS ONE 4(3): e4667, 2009.
Published online 2 March 2009.
doi:10.1371/journal.pone.0004667

Main source: Emory University.

Written by: Catharine Paddock, PhD