A recombinant baculovirus containing the S1 glycoprotein gene of the virulent nephropathogenic KM91 strain of infectious bronchitis virus (IBV) was constructed in order to investigate protective immunity in vaccinated chickens. Results from the protection test were evaluated by re-isolation of virus from the kidneys and tracheas of vaccinated chickens after challenge with strain KM91. After three immunizations, the recombinant S1 (rS1) glycoprotein induced 50 % protection of the kidney, whilst inactivated KM91 induced 88 % and 50 % protection of the kidney and trachea, respectively.

Among the eight equid herpesviruses identified to date (52), equine herpesvirus 1 (EHV-1) is one of the most pathogenic herpesviruses of horses, causing spontaneous abortions in pregnant mares, as well as respiratory tract infections and neurological disorders (1,12,45). The virus is a member of the subfamily Alphaherpesvirinae and serves as a model for the investigation of alphaherpesvirus gene regulation during both productive and persistent infections. The 77 EHV-1 genes are temporally and coordinately expressed at immediate-early (IE), early, and late (␥1 and ␥2) times of the lytic infection cycle (8, 18), analogous to that of herpes simplex virus type 1 (HSV-1) (11,33). In contrast to HSV-1, EHV-1 carries only one IE gene (also termed IR1 gene) that is expressed without prior viral protein synthesis due to the EHV-1 ␣-trans-inducing factor (ETIF), a homolog of the HSV-1 VP16 protein (14,41,47). The EHV-1 IE gene (i) is located within each invertedrepeat region and encodes a polypeptide of 1,487 amino acids (aa) with a predicted molecular mass of approximately 155 kDa (19,21,27), (ii) has a product with a high degree of homology with HSV-1 ICP4 and the varicella-zoster virus ORF62 gene products (21), and (iii) is transcribed as a 6.0-kb spliced mRNA (19,27,51) that gives rise to both structurally and antigenically related protein species ranging from 125 to 200 kDa (7,8,51). In transient-cotransfection assays, the IE protein is a bifunctional regulatory protein capable of (i) negatively autoregulating its own promoter (55), (ii) independently activating EHV-1 early and heterologous viral promoters (55, 56), (iii) cooperating synergistically with two early auxiliary regulatory proteins (EICP22 and EICP27) to activate EHV-1 early and ␥1 late promoters (32,44,55,57,64), and (iv) acting antagonistically with a third early major regulatory protein, EICP0, to selectively repress expression of certain promoters from all classes of EHV-1 promoters, including ␥2 late promoters (3,35).Sequence alignment of the EHV-1 IE protein and other homologs in the subfamily Alphaherpesvirinae defined five colinear regions that harbor specific functional domains. Region 1 contains an acidic transactivation domain (TAD; aa 3 to 89) (58) and a serine-rich tract (SRT; aa 181 to 220). Regions 2 and 3 harbor a helix-loop-helix motif that mediates a sequencespecific DNA-binding activity (aa 422 to 597) (38), while the nuclear localization signal (aa 963 to 970) lies within region 3 (56). Region 5 contains a transcriptional-enhancement domain that is required for the full transactivation activity of the IE protein (5, 56

Forty Korean isolates and four reference strains of infectious bronchitis virus (IBV) were classified by reverse transcriptase-polymerase chain reaction and restriction fragment length polymorphism (RFLP) analysis. Each Korean isolate was isolated from different types of commercial chicken flocks between 1986 and 1997. RFLP patterns of an amplified DNA fragment (1722 bp) containing the S1 gene of IBV digested by restriction enzyme HaeIII showed that the 40 Korean isolates were classified into five genotypes, I to V. Six of them belonged to genotype I which had the same HaeIII and XcmI cleavage patterns with Massachusetts type (H120 and M41) but the other four genotypes had a different HaeIII cleavage pattern from the four reference IBV strains used in this study. Genotype III seemed to be the major type as 29 of the 40 isolates belonged to this type which was consistently found in the chicken flocks since 1990. On the other hand, genotypes II, IV and V were found in the field only in 1986,1995 and 1995, respectively. Five isolates selected from each of the five genotypes were inoculated into 1-day-old specific-pathogen-free chicks to evaluate their pathogenicity. Genotype III induced 50% mortality as well as severe renal urate deposition on the kidneys but the other four genotypes only showed respiratory distress at 1 to 2 days after inoculation. Live H120 vaccine protected chicks against challenge with isolates selected from genotype I, but not genotypes IV to V. A live KM91pl20 strain selected from major genotype III did protect chicks against challenge with isolates from genotype III, in addition to other genotypes, including two recent isolates of genotypes IV and V.

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The equine herpesvirus 1 (EHV-1) immediate-early (IE) and EICP0 proteins are potent trans-activators of EHV-1 promoters; however, in transient-transfection assays, the IE protein inhibits the trans-activation function of the EICP0 protein. Assays with IE mutant proteins revealed that its DNA-binding domain, TFIIB-binding domain, and nuclear localization signal may be important for the antagonism between the IE and EICP0 proteins. In vitro interaction assays with the purified IE and EICP0 proteins indicated that these proteins interact directly. At late times postinfection, the IE and EICP0 proteins colocalized in the nuclei of infected equine cells. Transient-transfection assays showed that the EICP0 protein trans-activated EHV-1 promoters harboring only a minimal promoter region (TATA box and cap site), suggesting that the EICP0 protein trans-activates EHV-1 promoters by interactions with general transcription factor(s). In vitro interaction assays revealed that the EICP0 protein interacted directly with the basal transcription factors TFIIB and TBP and that the EICP0 protein (amino acids [aa] 143 to 278) mediated the interaction with aa 125 to 174 of TFIIB. Our unpublished data showed that the IE protein interacts with the same domain (aa 125 to 174) of TFIIB and with TBP. Taken together, these results suggested that interaction of the EICP0 protein with the IE protein, TFIIB, and TBP may mediate the antagonism between the IE and EICP0 proteins.The immediate-early (IE) gene of equine herpesvirus 1 (EHV-1) is essential for replication (16), lies within each of the two inverted repeats, and encodes a 1,487-amino-acid (aa) polypeptide (21). The IE protein trans-activates EHV-1 and heterologous viral promoters and trans-represses its own expression (56, 57). Residues 422 to 597 of the IE protein are sufficient for its sequence-specific DNA binding to the consensus binding sequence 5Ј-ATCGT-3Ј that overlaps the transcription initiation site of the IE promoter and to sequences in the E and L promoters that contain a degenerate version of this cognate cis element (36). A potent transcriptional activation domain lies within the first 89 aa residues of the IE protein (58), and aa 963 to 970 are necessary for nuclear localization of truncated IE polypeptides (57). The IE protein binds to the transcription initiation site of the glycoprotein K (gK) promoter sequences, thereby repressing transcription of this true late gene (35). The EICP0 protein is able to release the ␥2 L gK promoter from repression mediated by the IE protein (35). EHV-1 EICP22 (ICP22 homolog) (27), EICP27 (ICP27 homolog) (64), and EICP0 (2) are regulated as E genes, in contrast to the case for herpes simplex virus type 1 (HSV-1), in which the homologs of these three regulatory genes are members of the IE gene family (29,42). The EICP22 protein physically interacts with the IE protein (11, 12) and increases the in vitro DNA-binding activity of the IE protein for sequences in the IE, E, and L promoters (37).The EICP0 gene of the KyA virus encodes a prot...