How the Immune System Responds to Hepatitis A Virus

[Guest guest]

http://www.sciencedaily.com/releases/2011/06/110620161302.htm How the Immune

System Responds to Hepatitis A Virus ScienceDaily (June 21, 2011) — A surprising

finding in a study comparing hepatitis C virus (HCV) with hepatitis A virus

(HAV) infections in chimpanzees by a team that includes scientists from the

Texas Biomedical Research Institute sheds new light on the nature of the body's

immune response to these viruses.Understanding how hepatitis C becomes chronic

is very important because some 200 million people worldwide and 3.2 million

people in the U.S. are chronically infected with HCV and are at risk for

progression to cirrhosis and liver cancer. Hepatitis C associated liver disease

is the most common indication for liver transplantation, while liver cancer due

to HCV infection is now the most rapidly increasing cause of cancer death in the

U.S. " Remarkably, we found that HAV was more adept at evading the innate immune

response than HCV, the virus that ultimately causes chronic infections, " said

E. Lanford, Ph.D., a Texas Biomed virologist. The novel findings

demonstrate that HAV is the stealthier virus when it comes to evading the innate

immune response, despite the lack of persistent infections.Hepatitis C

infections are characterized by a failure of the immune system to combat and

eliminate the virus. " We suspect this failure of the immune system shares

attributes with other persistent viruses such as HIV and hepatitis B virus, "

said Lanford. By comparing two similar viruses that infect the liver, one that

is always cleared by the immune system, HAV, and one that frequently evades the

immune response, HCV, the team hoped to unravel the mystery of how HCV causes

lifelong persistent infections. The research team involved scientists from Texas

Biomed in San , the University of North Carolina (UNC) at Chapel Hill,

and Nationwide Children's Hospital in Columbus, Ohio. The study performed in

chimpanzees at Texas Biomed's Southwest National Primate Research Center (SNPRC)

and funded by the National Institutes of Health, is published June 20 in

Proceedings of the National Academy of Sciences U.S.A. The new study points out

the critical need for more information about how the immune system reacts to

HCV. It also reinforces the importance of chimpanzee research in this effort.

The chimpanzee, the only animal model susceptible to HCV infection, was critical

for probing the molecular differences in gene expression in the liver related to

infection by the two viruses.Examination of the adaptive immune system by

co-author M. , Ph.D., of Nationwide Children's Hospital in

Columbus, Ohio, found that the T cell response to HAV was unique as well. " We

expected the immune response to kill all HAV infected cells in a short time

frame, and yet we could detect the genome of the virus in the liver for up to

one year, long after symptoms of the disease were resolved, " Lanford explained.

" Hepatitis viruses have co-evolved with humans over a very long period of time

and they are good at evading the immune system, but nobody understands how

hepatitis C becomes a chronic infection, " said co-author Stanley M. Lemon, M.D.,

of UNC. " The surprising and exciting results of this research program further

highlight the critical value of the chimpanzee model in research on hepatitis, "

said L. VandeBerg, Ph.D., Texas Biomed's chief scientific officer and SNPRC

director Others on the study included Deborah Chavez, M.S., and Bernadette

Guerra, B.S., of Texas Biomed; Kathleen Brasky, D.V.M, of SNPRC; Zongdi Feng,

Ph.D., and Daisuke Yamane, D.V.M, Ph.D., of UNC; Yan Zhou, Ph.D., Nationwide

Children's Hospital; and Alan S. Perelson, Ph.D., of the Los Alamos National

Laboratory.Story Source:The above story is reprinted (with editorial adaptations

by ScienceDaily staff) from materials provided by Southwest Foundation for

Biomedical Research.Journal Reference: E. Lanford, Zongdi Feng, Deborah

Chavez, Bernadette Guerra, Kathleen M. Brasky, Yan Zhou, Daisuke Yamane, Alan S.

Perelson, M. , and Stanley M. Lemon. Acute hepatitis A virus

infection is associated with a limited type I interferon response and

persistence of intrahepatic viral RNA. PNAS, June 20, 2011 DOI:

10.1073/pnas.1101939108

[Guest guest]

http://www.sciencedaily.com/releases/2011/06/110620161302.htm How the Immune

System Responds to Hepatitis A Virus ScienceDaily (June 21, 2011) — A surprising

finding in a study comparing hepatitis C virus (HCV) with hepatitis A virus

(HAV) infections in chimpanzees by a team that includes scientists from the

Texas Biomedical Research Institute sheds new light on the nature of the body's

immune response to these viruses.Understanding how hepatitis C becomes chronic

is very important because some 200 million people worldwide and 3.2 million

people in the U.S. are chronically infected with HCV and are at risk for

progression to cirrhosis and liver cancer. Hepatitis C associated liver disease

is the most common indication for liver transplantation, while liver cancer due

to HCV infection is now the most rapidly increasing cause of cancer death in the

U.S. " Remarkably, we found that HAV was more adept at evading the innate immune

response than HCV, the virus that ultimately causes chronic infections, " said

E. Lanford, Ph.D., a Texas Biomed virologist. The novel findings

demonstrate that HAV is the stealthier virus when it comes to evading the innate

immune response, despite the lack of persistent infections.Hepatitis C

infections are characterized by a failure of the immune system to combat and

eliminate the virus. " We suspect this failure of the immune system shares

attributes with other persistent viruses such as HIV and hepatitis B virus, "

said Lanford. By comparing two similar viruses that infect the liver, one that

is always cleared by the immune system, HAV, and one that frequently evades the

immune response, HCV, the team hoped to unravel the mystery of how HCV causes

lifelong persistent infections. The research team involved scientists from Texas

Biomed in San , the University of North Carolina (UNC) at Chapel Hill,

and Nationwide Children's Hospital in Columbus, Ohio. The study performed in

chimpanzees at Texas Biomed's Southwest National Primate Research Center (SNPRC)

and funded by the National Institutes of Health, is published June 20 in

Proceedings of the National Academy of Sciences U.S.A. The new study points out

the critical need for more information about how the immune system reacts to

HCV. It also reinforces the importance of chimpanzee research in this effort.

The chimpanzee, the only animal model susceptible to HCV infection, was critical

for probing the molecular differences in gene expression in the liver related to

infection by the two viruses.Examination of the adaptive immune system by

co-author M. , Ph.D., of Nationwide Children's Hospital in

Columbus, Ohio, found that the T cell response to HAV was unique as well. " We

expected the immune response to kill all HAV infected cells in a short time

frame, and yet we could detect the genome of the virus in the liver for up to

one year, long after symptoms of the disease were resolved, " Lanford explained.

" Hepatitis viruses have co-evolved with humans over a very long period of time

and they are good at evading the immune system, but nobody understands how

hepatitis C becomes a chronic infection, " said co-author Stanley M. Lemon, M.D.,

of UNC. " The surprising and exciting results of this research program further

highlight the critical value of the chimpanzee model in research on hepatitis, "

said L. VandeBerg, Ph.D., Texas Biomed's chief scientific officer and SNPRC

director Others on the study included Deborah Chavez, M.S., and Bernadette

Guerra, B.S., of Texas Biomed; Kathleen Brasky, D.V.M, of SNPRC; Zongdi Feng,

Ph.D., and Daisuke Yamane, D.V.M, Ph.D., of UNC; Yan Zhou, Ph.D., Nationwide

Children's Hospital; and Alan S. Perelson, Ph.D., of the Los Alamos National

Laboratory.Story Source:The above story is reprinted (with editorial adaptations

by ScienceDaily staff) from materials provided by Southwest Foundation for

Biomedical Research.Journal Reference: E. Lanford, Zongdi Feng, Deborah

Chavez, Bernadette Guerra, Kathleen M. Brasky, Yan Zhou, Daisuke Yamane, Alan S.

Perelson, M. , and Stanley M. Lemon. Acute hepatitis A virus

infection is associated with a limited type I interferon response and

persistence of intrahepatic viral RNA. PNAS, June 20, 2011 DOI:

10.1073/pnas.1101939108

[Guest guest]

http://www.sciencedaily.com/releases/2011/06/110620161302.htm How the Immune

System Responds to Hepatitis A Virus ScienceDaily (June 21, 2011) — A surprising

finding in a study comparing hepatitis C virus (HCV) with hepatitis A virus

(HAV) infections in chimpanzees by a team that includes scientists from the

Texas Biomedical Research Institute sheds new light on the nature of the body's

immune response to these viruses.Understanding how hepatitis C becomes chronic

is very important because some 200 million people worldwide and 3.2 million

people in the U.S. are chronically infected with HCV and are at risk for

progression to cirrhosis and liver cancer. Hepatitis C associated liver disease

is the most common indication for liver transplantation, while liver cancer due

to HCV infection is now the most rapidly increasing cause of cancer death in the

U.S. " Remarkably, we found that HAV was more adept at evading the innate immune

response than HCV, the virus that ultimately causes chronic infections, " said

E. Lanford, Ph.D., a Texas Biomed virologist. The novel findings

demonstrate that HAV is the stealthier virus when it comes to evading the innate

immune response, despite the lack of persistent infections.Hepatitis C

infections are characterized by a failure of the immune system to combat and

eliminate the virus. " We suspect this failure of the immune system shares

attributes with other persistent viruses such as HIV and hepatitis B virus, "

said Lanford. By comparing two similar viruses that infect the liver, one that

is always cleared by the immune system, HAV, and one that frequently evades the

immune response, HCV, the team hoped to unravel the mystery of how HCV causes

lifelong persistent infections. The research team involved scientists from Texas

Biomed in San , the University of North Carolina (UNC) at Chapel Hill,

and Nationwide Children's Hospital in Columbus, Ohio. The study performed in

chimpanzees at Texas Biomed's Southwest National Primate Research Center (SNPRC)

and funded by the National Institutes of Health, is published June 20 in

Proceedings of the National Academy of Sciences U.S.A. The new study points out

the critical need for more information about how the immune system reacts to

HCV. It also reinforces the importance of chimpanzee research in this effort.

The chimpanzee, the only animal model susceptible to HCV infection, was critical

for probing the molecular differences in gene expression in the liver related to

infection by the two viruses.Examination of the adaptive immune system by

co-author M. , Ph.D., of Nationwide Children's Hospital in

Columbus, Ohio, found that the T cell response to HAV was unique as well. " We

expected the immune response to kill all HAV infected cells in a short time

frame, and yet we could detect the genome of the virus in the liver for up to

one year, long after symptoms of the disease were resolved, " Lanford explained.

" Hepatitis viruses have co-evolved with humans over a very long period of time

and they are good at evading the immune system, but nobody understands how

hepatitis C becomes a chronic infection, " said co-author Stanley M. Lemon, M.D.,

of UNC. " The surprising and exciting results of this research program further

highlight the critical value of the chimpanzee model in research on hepatitis, "

said L. VandeBerg, Ph.D., Texas Biomed's chief scientific officer and SNPRC

director Others on the study included Deborah Chavez, M.S., and Bernadette

Guerra, B.S., of Texas Biomed; Kathleen Brasky, D.V.M, of SNPRC; Zongdi Feng,

Ph.D., and Daisuke Yamane, D.V.M, Ph.D., of UNC; Yan Zhou, Ph.D., Nationwide

Children's Hospital; and Alan S. Perelson, Ph.D., of the Los Alamos National

Laboratory.Story Source:The above story is reprinted (with editorial adaptations

by ScienceDaily staff) from materials provided by Southwest Foundation for

Biomedical Research.Journal Reference: E. Lanford, Zongdi Feng, Deborah

Chavez, Bernadette Guerra, Kathleen M. Brasky, Yan Zhou, Daisuke Yamane, Alan S.

Perelson, M. , and Stanley M. Lemon. Acute hepatitis A virus

infection is associated with a limited type I interferon response and

persistence of intrahepatic viral RNA. PNAS, June 20, 2011 DOI:

10.1073/pnas.1101939108

[Guest guest]

http://www.sciencedaily.com/releases/2011/06/110620161302.htm How the Immune

System Responds to Hepatitis A Virus ScienceDaily (June 21, 2011) — A surprising

finding in a study comparing hepatitis C virus (HCV) with hepatitis A virus

(HAV) infections in chimpanzees by a team that includes scientists from the

Texas Biomedical Research Institute sheds new light on the nature of the body's

immune response to these viruses.Understanding how hepatitis C becomes chronic

is very important because some 200 million people worldwide and 3.2 million

people in the U.S. are chronically infected with HCV and are at risk for

progression to cirrhosis and liver cancer. Hepatitis C associated liver disease

is the most common indication for liver transplantation, while liver cancer due

to HCV infection is now the most rapidly increasing cause of cancer death in the

U.S. " Remarkably, we found that HAV was more adept at evading the innate immune

response than HCV, the virus that ultimately causes chronic infections, " said

E. Lanford, Ph.D., a Texas Biomed virologist. The novel findings

demonstrate that HAV is the stealthier virus when it comes to evading the innate

immune response, despite the lack of persistent infections.Hepatitis C

infections are characterized by a failure of the immune system to combat and

eliminate the virus. " We suspect this failure of the immune system shares

attributes with other persistent viruses such as HIV and hepatitis B virus, "

said Lanford. By comparing two similar viruses that infect the liver, one that

is always cleared by the immune system, HAV, and one that frequently evades the

immune response, HCV, the team hoped to unravel the mystery of how HCV causes

lifelong persistent infections. The research team involved scientists from Texas

Biomed in San , the University of North Carolina (UNC) at Chapel Hill,

and Nationwide Children's Hospital in Columbus, Ohio. The study performed in

chimpanzees at Texas Biomed's Southwest National Primate Research Center (SNPRC)

and funded by the National Institutes of Health, is published June 20 in

Proceedings of the National Academy of Sciences U.S.A. The new study points out

the critical need for more information about how the immune system reacts to

HCV. It also reinforces the importance of chimpanzee research in this effort.

The chimpanzee, the only animal model susceptible to HCV infection, was critical

for probing the molecular differences in gene expression in the liver related to

infection by the two viruses.Examination of the adaptive immune system by

co-author M. , Ph.D., of Nationwide Children's Hospital in

Columbus, Ohio, found that the T cell response to HAV was unique as well. " We

expected the immune response to kill all HAV infected cells in a short time

frame, and yet we could detect the genome of the virus in the liver for up to

one year, long after symptoms of the disease were resolved, " Lanford explained.

" Hepatitis viruses have co-evolved with humans over a very long period of time

and they are good at evading the immune system, but nobody understands how

hepatitis C becomes a chronic infection, " said co-author Stanley M. Lemon, M.D.,

of UNC. " The surprising and exciting results of this research program further

highlight the critical value of the chimpanzee model in research on hepatitis, "

said L. VandeBerg, Ph.D., Texas Biomed's chief scientific officer and SNPRC

director Others on the study included Deborah Chavez, M.S., and Bernadette

Guerra, B.S., of Texas Biomed; Kathleen Brasky, D.V.M, of SNPRC; Zongdi Feng,

Ph.D., and Daisuke Yamane, D.V.M, Ph.D., of UNC; Yan Zhou, Ph.D., Nationwide

Children's Hospital; and Alan S. Perelson, Ph.D., of the Los Alamos National

Laboratory.Story Source:The above story is reprinted (with editorial adaptations

by ScienceDaily staff) from materials provided by Southwest Foundation for

Biomedical Research.Journal Reference: E. Lanford, Zongdi Feng, Deborah

Chavez, Bernadette Guerra, Kathleen M. Brasky, Yan Zhou, Daisuke Yamane, Alan S.

Perelson, M. , and Stanley M. Lemon. Acute hepatitis A virus

infection is associated with a limited type I interferon response and

persistence of intrahepatic viral RNA. PNAS, June 20, 2011 DOI:

10.1073/pnas.1101939108