The complete VP1 protein of EV71 was truncated into six segments and fused to the C-terminal ends of full-length nucleocapsid protein (NPfl) and truncated NP (NPt; lacks 20% amino acid residues from its C-terminal end) of newcastle disease virus (NDV). Western blot analysis using anti-VP1 rabbit serum showed that the N-terminal region of the VP1 protein contains a major antigenic region. The recombinant proteins carrying the truncated VP1 protein, VP1(1-100), were expressed most efficiently in Escherichia coli as determined by Western blot analysis. Electron microscopic analysis of the purified recombinant protein, NPt-VP(1-100) revealed that it predominantly self-assembled into intact ring-like structures whereas NPfl-VP(1-100) recombinant proteins showed disrupted ring-like formations. Rabbits immunized with the purified NPt-VP(1-100) and NPfl-VP(1-100) exhibited a strong immune response against the complete VP1 protein. The antisera of these recombinant proteins also reacted positively with authentic enterovirus 71 and the closely related Coxsackievirus A16 when analyzed by an immunofluorescence assay suggesting their potential as immunological reagents for the detection of anti-enterovirus 71 antibodies in serum samples.
This report extends the knowledge on the epizootical situation of foot-and-mouth disease in Asia. RNA from six samples of type A and five of type O virus, isolated between 1987 and 1997 in Bangladesh, Iran, Malaysia and Turkey, was subjected to reverse transcription-dependent polymerase chain reactions that amplify large parts of the capsid protein VP1 encoding genome region. The amplification products were sequenced, and the sequences aligned to each other and to published sequences. This showed the type O isolates of 1987-1997 from Bangladesh to be of same genotype and closely related to isolates of 1988 and later from Saudi Arabia, 1990 from India, 1996 from Greece and Bulgaria, and 1997 from Iran. Among the analyzed type A isolates, those of 1992 and 1996 from Turkey were of same genotype and related to previously described isolates of 1987 from Iran and of 1992 from Saudi Arabia. The isolate of 1997 from Malaysia was found to be related to isolates from Thailand of 1993 and 1996. The isolates of 1987 from Bangladesh and 1997 from Iran, however, represent different so far not described genotypes. Monoclonal antibodies, raised against the vaccine production strains A22 Iraq, Asial Shamir, O1 Kaufbeuren and O1 Manisa, and the recent type A field isolates Saudi Arabia/92 and Albania/96, were used in an ELISA to compare the reaction patterns of many of the field isolates. The monoclonal antibodies were further characterized for virus-neutralizing activity and binding to trypsinized homologous virus. The failure of neutralizing antibodies in binding to trypsinized homologous as well as to heterologous virus suggested the epitopes to reside at the major antigenic component of the virus, which is the capsid protein VP1. Two non-neutralizing antibodies that bind to trypsin-sensitive epitopes cross-reacted, however, with heterologous virus. This indicates the existence of a trypsin-sensitive antigenic site outside of VP1. In summary, the results obtained by ELISA confirm the observed sequence differences, but indicate further sequence differences at minor antigenic sites that do not reside on VP1.
Rice tungro spherical virus (RTSV) has an RNA genome of more than 12 kb with various features which classify it as a plant picornavirus. The capsid comprises three coat protein (CP) species, CP1, CP2 and CP3, with predicted molecular masses of 22.5, 22.0 and 33 kDa, respectively, which are cleaved from a polyprotein. In order to obtain information on the properties of these proteins, each was expressed in E. coli, purified as a fusion to the maltose-binding protein and used for raising a polyclonal antiserum. CP1, CP2 and CP3 with the expected molecular masses were detected specifically in virus preparations. CP3 is probably the major antigenic determinant on the surface of RTSV particles, as was shown by ELISA, Western blotting and immunogold electron microscopy using antisera obtained against whole virus particles and to each CP separately. In some cases, especially in crude extracts, CP3 antiserum detected several other proteins (40-42 kDa), which could be products of CP3 post-translational modification. No serological differences were detected between the three CPs from isolates from the Philippines, Thailand, Malaysia and India. The CP3-related 40-42 kDa proteins of the Indian RTSV isolate have a slightly higher electrophoretic mobility (42-44 kDa) and a different response to cellulolytic enzyme preparations, which allows them to be differentiated from south-east Asian isolates.
Enterovirus 71 (EV71) infection may cause severe neurological complications, particularly in young children. Despite the risks, there are still no commercially available EV71 vaccines. Hence, a candidate vaccine construct, containing recombinant Newcastle disease virus capsids that display an EV71 VP1 fragment (NPt-VP1(1-100) ) protein, was evaluated in a mouse model of EV71 infection. Previously, it was shown that this protein construct provoked a strong immune response in vaccinated adult rabbits. That study, however, did not address the issue of its effectiveness against EV71 infection in young animals. In the present study, EV71 viral challenge in vaccinated newborn mice resulted in more than 40% increase in survival rate. Significantly, half of the surviving mice fully recovered from their paralysis. Histological analysis of all of the surviving mice revealed a complete clearance of EV71 viral antigens from their brains and spinal cords. In hind limb muscles, the amounts of the antigens detected correlated with the degrees of tissue damage and paralysis. Findings from this study provide evidence that immunization with the NPt-VP1(1-100) immunogen in a newborn mouse model confers partial protection against EV71 infection, and also highlights the importance of NPt-VP1(1-100) as a possible candidate vaccine for protection against EV71 infections.
The titres of IgA against Epstein-Barr virus, viral capsid antigens and the titres of IgG against early antigen were found to be useful markers for the diagnosis of different histopathological types of nasopharyngeal carcinoma.
The antibody titres to P. falciparum and Epstein-Barr Virus-associated antigens were assayed in 22 patients with NPC and 43 controls. All, but one patient had antimalarial titres; 14 had titres greater than 80 and 4 patients greater than 640. Compared to controls the mean anti-malarial titre for most age groups were higher in the patients. Those patients with high anti-malarial titres also had high IgA anti-VCA titre, an antibody which has been demonstrated to be diagnostic for NPC. The peak anti-VCA (IgG) and anti-EA (IgG) antibody titres were associated with anti-falciparum titres of 320-640 and 80-160, respectively. The results are discussed in relation to the possible association between malarial infection and etiology of NPC.
Epstein-Barr virus (EBV) receptors (EBV/C3d receptors) were detected, using the monoclonal antibody HB5, on 23 ectocervical and 5 endocervical biopsies of the uterine cervix. Elevated IgA titers against the viral capsid antigen and early antigen of EBV were also found in the cervical secretions from cervical carcinoma patients (83%), compared with samples from patients with cervical intraepithelial neoplasia (75%), herpes simplex virus-infected patients (0%), and gynecologic patients with nonmalignant conditions (0%). EBV DNA was present in 63% of cervical carcinoma biopsies detected by in situ hybridization. These observations suggest a positive association between EBV and carcinoma of the cervix.