Following dexamethasone treatment, viral nucleic acid was detected simultaneously in trigeminal ganglionic neurons and lymphoid follicles of tonsil. LRT was detected at 6 and 24 h after dexamethasone treatment but not at 48 h. Dexamethasone-induced reactivation led to apoptosis that was localized to tonsillar lymphoid follicles. Taken together, these findings suggest that the tonsil is a site for persistence or latency from which virus can be reactivated by dexamethasone. We further hypothesize that the shedding of virus from the tonsil during reactivation plays a role in virus transmission.

Acute infection of cattle with bovine herpesvirus 1 (BHV-1) represses cell-mediated immunity, which can lead to secondary bacterial infections. Since BHV-1 can induce apoptosis of cultured lymphocytes, we hypothesized that these virus-host interactions occur in cattle. To test this hypothesis, we analyzed lymph nodes and peripheral blood mononuclear cells (PBMC) after calves were infected with BHV-1. In situ terminal deoxynucleotidyltransferase-mediated dUTP nick end-labeling (TUNEL) staining of lymphoid tissues (pharyngeal tonsil, cervical, retropharyngeal, and inguinal) was used to detect apoptotic cells. Calves infected with BHV-1 for 7 days revealed increased apoptotic cells near the corticomedullary junction in lymphoid follicles and in the subcapsular region. Increased frequency of apoptotic cells was also observed in the mucosa-associated lymphoid tissue lining the trachea and turbinate. Immunohistochemistry of consecutive sections from pharyngeal tonsil revealed that CD2+ T lymphocytes were positive for the BHV-1 envelope glycoprotein gD. The location of these CD2+ T lymphocytes in the germinal center suggested that they were CD4+ T cells. Electron microscopy and TUNEL also revealed apoptotic and herpesvirus-infected lymphocytes from this area. Fluorescence-activated cell sorting analyses demonstrated that CD4+ and CD8+ T cells decreased in lymph nodes and PBMC after infection. The decrease in CD4+ T cells correlated with an increase in apoptosis. CD4+ but not CD8+ lymphocytes were infected by BHV-1 as judged by in situ hybridization and PCR, respectively. Immediate-early (bovine ICP0) and early (ribonucleotide reductase) transcripts were detected in PBMC and CD4+ lymphocytes prepared from infected calves. In contrast, a late transcript (glycoprotein C) was not consistently detected suggesting productive infection was not efficient. Taken together, these results indicate that BHV-1 can infect CD4+T cells in cattle, leading to apoptosis and suppression of cell-mediated immunity.

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The cellular and acellular envelopes of oocytes and follicles at the ultrastructural level are described for some acipenserids. The objective was to identify whether morphological features exist that can assist in discrimination of caviar products in trade originating from various species. The follicular envelopes include one thecal and one follicular cell layer separated by a basal lamina. The oocyte is surrounded by four acellular layers: (i) the internal zona radiata directly in contact with the oocyte plasma membrane; (ii) the external zona radiata; (iii) a layer of alveolar material; and (iv) a thin adhesive layer probably secreted by the follicular cells. These structures are similar in the eggs of genus Acipenser and Huso. Comparison of descriptions and definitions from different authors reveal a confusing terminology and sometimes different terms are used for similar structures. A terminology for the envelopes of Acipenseriform eggs is proposed. The authors conclude that morphological characters of sturgeon eggs are less valuable for discrimination of caviar.

We have examined the requirement for the transmembrane hydrophobic anchor sequence of the influenza hemagglutinin (HA) in the formation of the antigenic moiety on the surface of target cells recognized by class I MHC-restricted murine CTL. For this analysis we have used a line of CV-1 monkey epithelial cells that express the transfected murine H-2Kd gene product as target cells and have used recombinant SV40-based late replacement vectors to achieve expression of genes encoding wild-type and mutant forms of HA. We have found that the majority of Kd-restricted HA-specific CTL clones recognize target cells that express a secreted HA molecule that lacks the transmembrane and cytoplasmic domains of the parent glycoprotein. Several Kd-restricted CTL clones that recognize subtype-specific and crossreactive epitopes on HA fail to recognize the anchor-negative, secreted HA or chimeric HA molecules containing the transmembrane and cytoplasmic domains of unrelated glycoproteins. These CTL clones appear to be directed to antigenic epitopes located within the transmembrane domain of HA, as defined by their capacity to recognize target cells sensitized with a synthetic 23-amino-acid peptide corresponding to sequences within this domain. The implications of these results for class I MHC-restricted CTL recognition are discussed.