2006 MAY 24 - (NewsRx.com) -- Virol

2006 MAY 24 - (NewsRx.com) -- Virology data are the focus of recent research from the United States and Brazil.

Study 1: Investigators describe the selective transmission of hepatitis C virus genotypes and quasispecles in humans and experimentally infected chimpanzees.

According to their report, "This study determined whether selective transmission of hepatitis C virus (HCV) species occurred among human and chimpanzee recipients of contaminated blood products or plasma containing multiple genotypes, subgenotypes, and quasispecies."

"Commercially prepared factor VIII concentrate (lot DO56), produced prior to HCV testing and inactivation, was subsequently found by direct cloning to contain the following subgenotypes: 1a and 1b (73% of clones), 2a (13% of clones), 2b (11% of clones), and 3a (4% of clones)," said Omana V. Nainan and colleagues at the U.S. Centers for Disease Control and Prevention. "A patient transfused with factor VIII concentrate DO56 was diagnosed with clinical non- A, non-B hepatitis and subsequently found to be infected with HCV subgenotype 1b."

"Among five chimpanzees inoculated experimentally with the same factor VIII concentrate, two were infected only with HCV subgenotype 1a and three were infected with approximately equivalent clonal proportions of subgenotypes 1a and 1b," the researchers noted. "HCV hypervariable region 1 (HVR1) quasispecies analysis of the DO56 factor VIII concentrate and a serum specimen from the single chimpanzee that developed a chronic HCV infection following inoculation with DO56 showed 0-56% nucleotide variation. However, specimens from chimpanzees infected in the second to fourth passages of the DO56 inoculum had 0-8% HVR1 quasispecies nucleotide variation."

Nainan and associates concluded, "The high HVR1 quasispecies variation in the factor VIII concentrate and its first passage in chimpanzees indicates the presence of multiple HCV isolates, whereas the low variation in the second to fourth chimpanzee passages suggests transmission of a single HCV isolate. These findings strongly suggest selective transmission of HCV isolates during experimental chimpanzee infection and among humans exposed to multiple HCV species."

Nainan and coauthors published their study in the Journal of General Virology (Selective transmission of hepatitis C virus genotypes and quasispecles in humans and experimentally infected chimpanzees. J Gen Virol, 2006;87(Part 1):83-91).

For more information, contact Feng-Xiang Gao, Division of Viral Hepatitis, National Center for Infectious Diseases, Centers for Disease Control and Prevention, 1600 Clifton Road NE, MS A33, Atlanta, GA 30333, USA. Fgao@cdc.gov.

Study 2: Hepatitis C virus (HCV) RNA in saliva does not reflect oral health or viral load.

"HCV is a worldwide public health problem and its transmission is clearly associated with the parenteral route, however, the virus has also been isolated from other body fluids. HCV RNA has been detected in saliva, yet the relationship between HCV and oral pathology is not clearly understood," investigators in Brazil report.

"Therefore, an investigation on HCV-RNA in saliva and its correlation with oral pathology was undertaken. Saliva and blood samples were collected from 50 anti-HCV positive patients and from 25 patients with non-HCV chronic liver disease. HCV-RNA was detected in all of the saliva samples from the HCV positive group," wrote L. Lins and colleagues, Centro de Pesquisas Goncalo Moniz.

"None of the saliva or serum samples from the non-HCV group were positive for HCV-RNA. The patients were examined for dental and oral health (dentate, partially dentate, edentulous, evidence of gum disease, or mucosal lesions); however, no correlation was found between HCV-RNA in saliva, oral health, and viral load."

"These results suggest that HCV-RNA presence in saliva is independent of the viral load and the oral pathology of HCV positive individuals," scientists concluded.

Lins and colleagues published their study in the Journal of Medical Virology (Detection of hepatitis C virus RNA in saliva is not related to oral health status or viral load. J Med Virol, 2005;77(2):216-220).

For additional information, contact M.G. Reis, FIOCRUZ MS, Center Pesquisa Goncalo Moniz, Laboratory Patol & Biology Molecular, R Waldemar Falcao 121, BR-40295001 Salvador, BA, Brazil.

Study 3: Hepatitis C virus (HCV) replication strengthens upon CD8+ T cell depletion.

According to researchers in the United States, "we investigated the ability of CD8+ T cells to inhibit HCV replication in peripheral blood mononuclear cells (PBMCs). PBMCs isolated from 11 of 20 HCV- infected subjects had no detectable HCV RNA."

"Removal of CD8+ T cells from these PBMCs resulted in detection of HCV RNA, and depletion of CD8+ T cells from PBMCs that had detectable HCV RNA amplified HCV replication. Reconstitution of CD8- PBMCs with autologous CD8+ T cells led to inhibition of HCV replication," reported Y. Li and colleagues, University of Pennsylvania.

"Interferon-gamma produced by CD8+ T cells was partially responsible for CD8+ T cell-mediated noncytotoxic anti-HCV activity in PBMCs. This noncytotoxic anti-HCV activity was confirmed in HCV replicon cells. Supernatants from CD8+ T cell cultures inhibited HCV RNA expression in the replicon cells."

"These findings may have important implications for the immunopathogenesis of HCV in both immune and hepatic cells and are relevant to the development of host innate immunity-based anti-HCV interventions," researchers stated.

Li and colleagues published the results of their research in the Journal of Infectious Diseases (CD8+ T cell depletion amplifies hepatitis C virus replication in peripheral blood mononuclear cells. J Infect Dis, 2005;192(6):1093-1101).

For additional information, contact W.Z. Ho, University of Penn, Children's Hospital Philadelphia, Division Allergy & Immunology, Joseph Stokes Jr Research Institute, School of Medicine, Dept. Pediatrics, 34th St. & Civic Center Blvd., Philadelphia, PA 19104, USA.

Keywords: Philadelphia, Pennsylvania, United States, Cell Mediated Immunity, Hepatitis C Virus, Hepatology, Immunology, Infectious Disease, Interferon, Antiviral Therapy, Hematology, Peripheral Blood, Virology, CD8+ T Cell, Replication.

This article was prepared by Medical Letter on the CDC & FDA editors from staff and other reports. Copyright 2006, Medical Letter on the CDC & FDA via NewsRx.com.
Word count: 943

(c)Copyright 2006, Medical Letter on the CDC & FDA viaNewsRx.com


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Subject
Virology
Medical research
Hepatitis
Infectious diseases
Antiretroviral drugs

Location
United States
US
Braz