No abstract

During an epidemiological study on rotaviruses among diarrheic children in the northeastern and middle belt regions of Nigeria, the distribution of G and P types was investigated in 127 stool specimens. By PCR G typing, the G type of rotaviruses in 97 samples was identified. Interestingly, an unusual G8 type, as well as common G1, G2, and G3 types, was detected more frequently (31 of 112; 27.7%). Eleven samples contained multiple G types, and a G9 strain (Bulumkutu) was identified for one of the probable mixed infections. In PCR P typing, P[6] was detected most frequently, P[8] being the second most common type, while the P type of 73 samples could not be identified. One rotavirus strain with a G8 type specificity could be cultivated in cell culture, and the P type of this strain was found to be P[1], which is usually carried by bovine strains. When the combinations of G and P types were examined, the unusual strains G2P[6] and G8P[1] were often identified. Sequence analysis was performed for the VP7 gene of the G9 strain Bulumkutu and the VP4 and VP7 genes of G8P[1] strain HMG035. The VP7 sequence of the Nigerian serotype G9 was more closely related to that of a Brazilian strain than to those of other African strains. The VP7 and VP4 genes of G8P[1] strain HMG035 were found to be very similar to that of a Thai bovine strain A5, suggesting that bovine strains may have been transmitted directly to humans. These results highlight an unexpected diversity among rotavirus strains in Nigeria and emphasize the need for further serological and genetic surveys on more rotavirus strains in African countries, including Nigeria.

A rotavirus strain HMG89 from Nigeria with short electrophoretic pattern was typed G3 by PCR. A cDNA clone from the PCR product which hybridised in Northern blots to RNA segment 9 of the homologous Nigerian rotavirus strain HMG89 and laboratory reference strain 69M but not to other mammalian group A rotaviruses was sequenced. The VP7 gene 9 sequence is 1060 nucleotides long with two base deletions at positions 1034-1035. Sequence analysis of the primer (aAT8) used in the previous PCR serotyping assay revealed a mutation in one of the three nucleotide bases at the 3' end of the primer binding site accounting for our inability to serotype G8 strains in our samples. These findings demonstrate that PCR analysis can, albeit infrequently, lead to error in typing of rotaviruses due to small numbers of mutations in the primer binding region.

Hepatitis C virus (HCV) isHepatitis C virus (HCV) is a major cause of posttransfusion and community-acquired hepatitis in the world (8,24,25). The majority of HCV-infected individuals develop chronic hepatitis that may progress to liver cirrhosis and hepatocellular carcinoma (15). Treatment options for chronic HCV infection are limited, and a vaccine to prevent HCV infection is not available (11,15,17).HCV has been classified in a separate genus (Hepacivirus) of the Flaviviridae family. The virion contains a positive-stranded RNA genome of approximately 9.6 kb in length (25). The genome consists of a highly conserved 5Ј noncoding region followed by a long open reading frame of 9,030 to 9,099 nucleotides that is translated into a single polyprotein of 3,010 to 3,030 amino acids. Processing of the polyprotein occurs by a combination of host and viral proteases. The HCV structural proteins comprise the putative nucleocapsid or core protein and the two envelope glycoproteins E1 and E2 (25). The E2 glycoprotein is thought to be responsible for initiating virus attachment due to its ability to bind to human cells (32).HCV purified from plasma has been reported to exist in association with plasma lipoproteins, suggesting that the virus may use the low-density lipoprotein receptor for uptake (2). In the absence of highly purified native infectious HCV particles as a tool for the study of virus-cell interaction, recombinant HCV glycoprotein E2, E1E2 liposomes (22), infectious HCV pseudotype particles expressing E1 and E2 (HCVpp) (4, 16), and HCV-like particles (HCV-LPs) (3,39,41) have been used to analyze virus-cell membrane interaction. Based on these experimental in vitro studies, CD81 (5, 32), dendritic cellspecific intercellular adhesion molecule 3 grabbing nonintegrin (33) and highly sulfated heparan sulfate (3) have been proposed to play a role in mediating E2 binding and/or HCV internalization.Recently, the scavenger receptor class B type I (SR-BI) has been proposed as a putative HCV receptor candidate (36). SR-BI, a high-density lipoprotein-binding molecule, plays a functional role in lipid metabolism and is highly expressed in hepatocytes and steroidgenic tissues (34). SR-BI is a 509-residue glycoprotein with a large extracellular loop (LEL) anchored to the plasma membrane at both the N and C termini by transmembrane domains with short extensions into the cytoplasm (21). SR-BI has been shown to play a role in mediating the binding of recombinant E2 to HepG2 hepatoma cells and the entry of recombinant HCVpp into Huh-7 hepatoma cells (5, 36). Due to the lack of convenient in vitro or in vivo models for the study of HCV infection, the