Preparation and identification of an antiserum against recombinant UL31 protein of pseudorabies virus.

Pseudorabies virus (PRV) early protein UL31 is a homologue of herpes simplex virus 1 (HSV-1) UL31, which is a multifunctional protein important for HSV-1 infection. However, the precise roles of PRV UL31 in virus life cycle are still poorly understood. A relatively crucial tool for uncovering the function of UL31 is an antiserum that specifically detects UL31 in the PRV-infected cells. For this purpose, a recombinant UL31 protein consisting of N-terminal 27 aa of UL31 fused to EYFP and His-tag was expressed, purified and used for the preparation of antiserum in BALB/c mice. Our results show that Western blot analysis and immunofluorescence assay showed that this antiserum could specifically detect the purified recombinant UL31 as well as full-length UL31 in the PRV infected cells. These results demonstrate that the prepared antiserum could serve as a valuable tool for further studies of UL31 functions in PRV infection.

Molecular cloning and characterization of the pseudorabies virus UL31 gene.

We amplified a 816-bp sequence of the UL31 gene from the pseudorabies virus (PRV) Becker strain genome. Evidence that this was the UL31 gene was confirmed by cloning and sequencing. The PRV UL31 gene encodes a putative protein of 271-amino acid residues, which was designated the UL31 protein. Bioinformatic analysis indicated that PRV UL31 contains a conserved PHA03328 domain, closely related with the herpes virus nuclear egress lamina protein UL31 family and highly conserved among counterparts encoded by herpes UL31 genes. Nucleic acid sequence and amino acid sequence alignments demonstrated that PRV UL31 has a relatively higher homology with UL31 homologous proteins of subfamily Alphaherpesvirinae than other subfamilies. In addition, phylogenetic analysis showed that PRV UL31 has a close evolutionary relationship with members of the subfamily Alphaherpesvirinae, especially bovine herpesvirus 1 (BoHV-1), BoHV-5, equine herpesvirus 4 (EHV-4), EHV-9 and EHV-1. Antigen prediction demonstrated that several potential B-cell epitopes are located in PRV UL31. Additionally, secondary structure and three-dimension structure prediction revealed that PRV UL31 predominantly consists of α-helix. Taken together, these results provide insight on the function and mechanism of UL31 during PRV infection.

Hepatitis B virus, aflatoxins, and hepatocellular carcinoma in southern Guangxi, China.

We examined the roles of the hepatitis B virus and aflatoxin B1 in the development of primary hepatocellular carcinoma (PHC) in a cohort of 7917 men aged 25 to 64 yr old in southern Guangxi, China, where the incidence of PHC is among the highest in the world. After accumulating 30,188 man-yr of observation, 149 deaths were observed, 76 (51%) of which were due to PHC. Ninety-one% (69 of 76) of PHC deaths were hepatitis B surface antigen (HBsAg) positive at enrollment into the study in contrast to 23% of all members of the cohort (RR = 38.6). Three of the four patients who died of liver cirrhosis also were HBsAg positive at enrollment. There was no association between HBsAg positivity state and other causes of death. Within the cohort, there was a 3.5-fold difference in PHC mortality by place of residence. When estimated aflatoxin B1 levels in the subpopulations were plotted against the corresponding mortality rates of PHC, a positive and almost perfectly linear relationship was observed. On the other hand, no significant association was observed when the prevalence of HBsAg positivity in the subpopulations was compared with their corresponding rates of PHC mortality.

Preserved foods and nasopharyngeal carcinoma: a case-control study in Guangxi, China.

One hundred twenty-eight mothers of nasopharyngeal carcinoma (NPC) cases under age 45 in Yulin Prefecture, China and 174 mothers of population controls were interviewed as part of an epidemiological study to examine childhood exposures in relation to the development of NPC. Exposure before age 2 years to a number of fermented foods was a risk factor for NPC. During weaning, intake of salted fish [relative risk (RR) = 2.6, one-sided P (P) = 0.01], salted duck eggs (RR = 5.0, P = 0.03), salted mustard green (RR = 5.4, P = 0.03), and chung choi (RR = 2.0), P = 0.003), a kind of salted root, was significantly related to an increased risk of NPC. Between ages 1 and 2 years, intake frequency of dried fish [P for linear trend test (linear trend P) = 0.002], fermented black bean paste (linear trend P = 0.0009), and fermented soy bean paste (linear trend P = 0.007) was also positively associated with NPC. A multivariate analysis of these different foods showed all except fermented black bean paste to be independently related to NPC.

Risk factors for hepatocellular carcinoma in Guangxi, People's Republic of China.

Fusui County in the Guangxi Autonomous Region of China is a high-risk area for hepatocellular carcinoma (HCC). In 1971-73, the average annual standardized (world population) mortality rate of HCC in Fusui was 20.09 and 111.75/100,000 person-years for females and males, respectively. Epidemiologic and pathologic studies of HCC have been conducted in Fusui since 1959. This paper describes some of the studies relating to the hepatitis B virus infection and aflatoxin contamination of foodstuffs.

A serological case-control study of primary hepatocellular carcinoma in Guangxi, China.

Guangxi is a very high-risk area for primary hepatocellular carcinoma (PHC); the age-standardized (world population) rates for males and females in that Chinese Autonomous Region were 32.5 and 8.5, respectively. Blood specimens from 50 PHC patients and 50 age- and sex-matched controls in Guangxi were analyzed for hepatitis B surface antigen, antibody to hepatitis B surface antigen, and antibody to hepatitis B core antigen. Eighty-six % of cases were hepatitis B surface antigen positive, compared to 22% of controls (relative risk, 17.0). We estimate from the data that persistent hepatitis B virus infection can account for at least 80% of all PHC cases occurring in Guangxi. The consistency of our findings with those from Hong Kong and Taiwan strongly suggests that hepatitis B virus infection is also an important risk factor for PHC in other parts of southern China.