Submitted to: Virus Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 7, 1998
Publication Date: N/A
Interpretive Summary: Emerging or newly discovered viruses are becoming more of a threat to both human and animal health. Some of these viruses belong to the calicivirus group of viruses. Two of the caliciviruses, human enteric calicivirus (HECV) and porcine enteric calicivirus (PECV), do not grow or only grow very poorly in cell cultures. HECV causes viral food poisoning and does not grow in culture. There is evidence that PECV may be involved in diarrhea outbreaks in swine herds. PECV grows very poorly but can serve as a model for the human viral infection. To better understand the immune response against caliciviruses in general, porcine caliciviruses that will grow in the laboratory were studied. We examined portions of the virus that antibodies are made against in the host animal following an infection. We found that changes in the calicivirus coat protein are responsible for altered antibody recognition of these viruses. Further research efforts can now be directed toward understanding these changes for a clearer knowledge of how antibodies are effective in inactivation of calicivirus particles. This information will allow researchers to understand immune responses against the caliciviruses and make useful veterinary and human vaccines possible.
Technical Abstract: Vesicular exanthema of swine virus (VESV), the prototype calicivirus, is the etiologic agent of the disease of swine called vesicular exanthema of swine (VES). VES is characterized by vesicle formation on the extremities, mouth and snout and causes abortions and stillbirths if infection occurs during pregnancy. The single capsid protein gene of VESV serotype A48 was cloned and sequenced. The capsid protein open reading frame was encoded i the 3'-terminal 2724 bases of the genomic RNA. The VESV A48 capsid protein was 69% similar to the San Miguel Sea lion virus serotype 1 (SMSV 1) and 89% similar to the SMSV serotype 4 capsid proteins. The six apparently functional regions (A-F) previously identified in SMSV 1, SMSV 4, feline calicivirus and rabbit hemorrhagic disease virus capsid proteins were present in VESV A48. Two sets of PCR primers were designed which directed amplification of the N-terminus of the capsid protein gene and the hypervariable region (region E) of the capsid protein of these and 7 additional SMSV serotypes. Alignment and phylogenetic analysis of the N-terminal sequences confirmed the close relationship of these viruses. Alignment analysis of the hypervariable region of the ten viruses revealed that there is great variety of sequence in this region; however, highly conserved residues were identified which are also conserved in the feline calicivirus capsid protein gene. These conserved amino acid residues are probably necessary for a conserved function in the animal caliciviruses. Comparison of these sequences provides further evidence that the E-region of the animal caliciviruses may contain the major antigenic determinants.