Flue

30 Apr 2013 —  Wilkinson et al. in 2012 showed that CD4+ T cells that are activated by earlier influenza virus infections reduce the severity of the disease.

 Why are some infections with certain flu virus strains fatal and others are not?



Why are some infections with certain flu virus strains fatal and others are not?
By Klaus D. Linse on April 30, 2013 • ( 0 )


The answer may be found in human CD4+ T cells

Virus specific memory CD4+ T cells numbers predict the outcome of human influenza infections

Wilkinson et al. in 2012 showed that CD4+ T cells that are activated by earlier influenza virus infections reduce the severity of the disease.

To gain insight into protective immunity against influenza virus infection mediated by neutralizing antibodies Wilkinson et al. in 2012 studied the role of T cells in humans that develop immunity against the influenza virus. The study enrolled 41 healthy human volunteers that had no detectable antibodies to the challenging viruses and challenged their immune system by inoculating them intranasally with serial dilutions of influenza A viruses H3N2 or H1N1. A large increase in influenza specific T cell responses could be observed by day 7. At this day the virus was completely cleared from the nasal samples and serum antibodies were still undetectable. Further, it was observed that preexisting CD4+ T cells responded to the influenza internal proteins, matrix and nucleoprotein. CD8+ T cells did not. The response of these CD+ T cells was associated with lower virus shedding and less severe illness. Furthermore, the CD4+ cells also responded to pandemic peptides from the H1N1 virus strain.

The researchers observed that immune responses from preexisting T cells against internal nucleoprotein and matrix protein as measured by IFN-γ responses were largely CD4+ T cell mediated in both H1N1 and H3N2 study groups. The following table contains a list of peptides that the research group identified at the single-peptide level.

M and NP Influenza A

M = matrix protein. NP = nucleoprotein..

.

A list of peptides that showed responses of preexisting T cells in challenge study subjects is shown in the tables below.

Response to the challenge with H3N2

Protein Peptide ID Amino acid position Sequence CD4 of CD8 dependency
M MO1 1-15 MSLLTEVETYVLSIV 8
M MO2 6-22 EVETYVLSIVPSGPLKA 4
M MO7 40-57 EALMEWLKTRPILSPLTK 8
M MO8 48–64 TRPILSPLTKGILGFVF 8
M M09 55–72 LTKGILGFVFTLTVPSER 8
M M15 103–119 LKREITFHGAKEIALSY 4
M M23 159–175 HRSHRQMVATTNPLIKH 4
M M25 173–189 IKHENRMVLASTTAKAM 4
NP NP05 24–41 EIRASVGKMIDGIGRFYI 4
NP NP08 48–65 KLSDHEGRLIQNSLTIEK 4
NP NP14 95–111 PIYRRVDGKWMRELVLY 4
NP NP15 102–119 GKWMRELVLYDKEEIRRI 4
NP NP16 110–29 LYDKEEIRRIWRQANNGEDA 4
NP NP20 141–156 SNLNDATYQRTRALVR 8
NP NP21 147–163 TYQRTRALVRTGMDPRM 8
NP NP27 192–208 ELIRMVKRGINDRNFWR 4
NP NP31 221–238 RMCNILKGKFQTAAQRAM 4
NP NP32 229–246 KFQTAAQRAMVDQVRESR 8
NP NP57 404–420 GQTSVQPTFSVQRNLPF 4
NP NP58 411–428 TFSVQRNLPFEKSTIMAA 4
Response to the challenge with H1N1

Protein Peptide ID Amino acid position Sequence CD4 of CD8 dependency
M M8 57–74 KGILGFVFTLTVPSERGL 4
M M12 89–106 DPNNMDRAVKLYRKLKRE 4
M M13 97–114 VKLYRKLKREITFHGAKE 4
M M14 105–122 REITFHGAKEIALSYSAG 4
M M27 209–226 ARQMVQAMRAIGTHPSSS 4
NP NP09 65–82 RMVLSAFDERRNKYLEEH 4
NP NP14 105–122 VRELVLYDKEEIRRIWRQ 4
NP NP22 169–186 GSTLPRRSGAAGAAVKGV 8
NP NP27 209–226 GENGRKTRIAYERMCNIL 8
NP NP28 217–234 IAYERMCNILKGKFQTAA 8
NP NP52 409–426 QPTFSVQRNLPFDKTTIM 4
.

Reference
Anne Kelso; CD4+ T cells limit the damage in influenza. Nature Medicine 18, 200–202 (2012). doi:10.1038/nm.2654.

Tom M Wilkinson, Chris K F Li, Cecilia S C Chui, Arthur K Y Huang, Molly Perkins, Julia C Liebner, Rob Lambkin-Williams, Anthony Gilbert, John Oxford, Ben Nicholas, Karl J Staples, Tao Dong, Daniel C Douek, Andrew J McMichael & Xiao-Ning Xu Preexisting influenza-specific CD4+ T cells correlate with disease protection against influenza challenge in humans. Nature Medicine 18, 274–280 (2012). doi:10.1038/nm.2612

Synthetic peptides are versatile tools to help develop vaccines against new Influenza A viral strains

Pools or libraries of synthetic peptides derived from Influenza A viral proteins can be used to screen for and identify human leukocyte class I (HLA-I) restricted cytotoxic T cell (CTL) epitopes.


Pools of libraries of synthetic peptides are ideal tools to determine hemaglutinin-specific antibody titers against the flu virus (Influenza Virus). A universal vaccine against the influenza virus could theoretically provide protection against all strains of influenza. The use of synthetic peptide for the development of such a vaccine is presently investigated as one route for vaccine development.

The U.S. Department of Health and Human Services and NIAID presently supports researchers to develop new influenza vaccine technologies. The goal is to help the United States and the world be better prepared and to mount a speedy response to the next pandemic caused by new Influenza A strains.

The NIAID is exploring several platforms to develop new vaccines

  • DNA-based Vaccines
  • Recombinant Subunit Vaccines
  • Microbial Vector Vaccines
  • Synthetic Peptide Vaccines
  • Universal Vaccines
  • Optimizing Vaccines and Vaccine Production
  • Regulatory Sciences to Increase Vaccine Availability

 

The 2013 H7N9 Influenza A Outbreak


Several cases of the new Influenza virus A H7N9 subtype were identified in Shanghai, China and surrounding provinces in March 2013.

Forbes reports on April 29, 2013 that “Shanghai on Monday reported another H7N9 bird flu death, an 89-year-old man who was admitted to a city hospital on April 12, according to the state-published Shanghai Daily newspaper.

The latest fatality raises to 13 the number of H7N9-related deaths in the city, which is one of China’s most important international business hubs. Nationwide, 24 people have died, the paper said.

The total number of H7N9 cases in the mainland stands at 125, not including one illness in Taiwan.  China’s government, which has territorial disputes with a number of Asian countries, also claims sovereignty over Taiwan’s 23 million people, and combines H7N9 case reporting from the two.

The newly discovered H7N9 disease has spread from eastern China both northward and southward, leading to the closure of wet markets where live chicken is sold as a preventative measure.  Early damage estimates to the country’s poultry industry have been at more than $1 billion.”

Since it is known that CD8+ cytotoxic T lymphocytes (CTL) responses play a major role in the control of primery influenza virus infection HLA-I CTL restricted peptides that contain CTL epitopes may allow the development of such a vaccine. Synthetic peptides can be produced chemically and don’t need to be grown in eggs or cell culture. Portions of influenza proteins containing CTL epitopes that stimulate antibody production can be synthesized and formulated into a vaccine to stimulate an immune response. However, peptides alone stimulate a very weak immune response therefore the use of an adjuvant or any other delivering method of peptides to the immune cells that can strengthen that response is needed.

Sequence information to select and design synthetic peptide epitope libraries can be retrieved from the influenza sequence databases:

http://www.flu.lanl.gov/,  http://www.fludb.org/

.Influenza Peptide Pools help scientists accelerate their research.