On the origin of Metazoan adhesion receptors: cloning of integrin alpha subunit from the sponge Geodia cydonium

Integrins are prominent receptors known from vertebrates and the higher phyla of invertebrates. Until now, no evidence has been provided for the existence of integrins in the lowest Metazoa, the sponges (Porifera). We have isolated and characterized a cDNA clone encoding the alpha subunit of integrin from the marine sponge Geodia cydonium (GCINTEG). The open reading frame encodes a polypeptide of 1,086 residues (118 kDa). The intracellular domain features the sequence Tyr- Phe-x-Gly-Phe-Phe-x-Arg, which is different in one residue from the characteristic consensus pattern for integrin alpha subunits. We conclude that sponges, the oldest multicellular animal phylum, already utilize the structural elements which are required for a tuned and controlled interaction among cells, and between cells and the extracellular matrix.      

Evidence for separate genetic defects in C3H/HeJ and C3HeB/FeJ mice, that affect susceptibility to gram-negative infections

Past studies have suggested a linkage between susceptibility to Salmonella typhimurium infection and the Lpsd genotype in C3H mice. Recently, this linkage was questioned by the finding that C3HeB/FeJ mice (Lpsn,Lpsn) were highly susceptible to systemic S. typhimurium infection. The present study shows a marked difference between C3H/HeJ and C3HeB/FeJ in their susceptibility to Gram-negative urinary tract infection. The number of E. coli and S. typhimurium recovered from the kidneys 24 hr after infection was 70 to 100 times higher in C3H/HeJ than in C3HeB/FeJ or C3H/HeN mice. Subsequently, in C3HeB/FeJ mice S. typhimurium multiplied to the level of C3H/HeJ mice, resulting in a shorter mean survival time of C3H/HeJ and C3HeB/FeJ compared with C3H/HeN mice. In contrast, E. coli remained localized to the urinary tract of C3H/HeJ mice but were eliminated from C3HeB/FeJ and C3H/HeN mice. Thus, experimental E. coli urinary tract infection appears to provide a method to differentiate the genetic defects of C3H/HeJ and C3HeB/FeJ mice. The results support an influence of the Lpsd genotype on clearance of Gram-negative bacteria from the kidneys of C3H mice.     

PIR-B-deficient mice are susceptible to Salmonella infection

Paired Ig-like receptors of activating (PIR-A) and inhibitory (PIR-B) isoforms are expressed by many hematopoietic cells, including B lymphocytes and myeloid cells. To determine the functional roles of PIR-A and PIR-B in primary bacterial infection, PIR-B-deficient (PIR-B(-/-)) and wild-type (WT) control mice were injected i.v. with an attenuated strain of Salmonella enterica Typhimurium (WB335). PIR-B(-/-) mice were found to be more susceptible to Salmonella infection than WT mice, as evidenced by high mortality rate, high bacterial loads in the liver and spleen, and a failure to clear bacteria from the circulation. Although blood levels of major cytokines and Salmonella-specific Abs were mostly comparable in the two groups of mice, distinct patterns of inflammatory lesions were found in their livers at 7-14 days postinfection: diffuse spreading along the sinusoids in PIR-B(-/-) mice vs nodular restricted localization in WT mice. PIR-B(-/-) mice have more inflammatory cells in the liver but fewer B cells and CD8(+) T cells in the spleen than WT mice at 14 days postinfection. PIR-B(-/-) bone marrow-derived macrophages (BMMphi) failed to control intracellular replication of Salmonella in vitro, in part due to inefficient phagosomal oxidant production, when compared with WT BMMphi. PIR-B(-/-) BMMphi also produced more nitrite and TNF-alpha upon exposure to Salmonella than WT BMMphi did. These findings suggest that the disruption of PIR-A and PIR-B balance affects their regulatory roles in host defense to bacterial infection.     

Major histocompatibility (B) complex effects on acquired immunity to cecal coccidiosis

The influence of the major histocompatibility (B) complex on acquired immunity to the avian coccidium Eimeria tenella was studied in 217 F₄ segregants (B ² B ², B ² B ⁵, B ⁵ B ⁵) of a cross between inbred lines 6₁ (B ² B ²) and 15₁ (B ⁵ B ⁵) and segregating haplotype combinations of UNH105 (B ²³ B ²³ B ²³ B ²⁴, B ²⁴ B ²⁴), a noninbred line of New Hampshire chickens. Chickens were immunized at 6 weeks of age with 500 oocysts daily for 5 days, then challenged 14 days later with 10000 oocysts. Responses to infection were evaluated by cecal lesion scores, body weight gain, delayed wattle reaction (DWR), and spleen weight. The F₄ segregants of genotypes B ² B ⁵ and B ⁵ B ⁵ exhibited greater immunity to challenge than B ² B ² chickens. B ⁵ B ⁵ chickens showed a significantly greater DWR following immunization and larger spleens 6 days after the challenge than either of the other genotypes. However, both BIBS and B ⁵ B ⁵ chickens demonstrated significantly lower lesion scores than B ² B ² chickens. There were no significant differences in weight gain among these genotypes. Among 139 line UNH105 segregants, B ²³ B ²³ hosts had significantly lower lesion scores than B ²⁴ B ²⁴ chickens. No other differences in immune response among line UNH105 genotypes were detected.     

Light chain diversity of murine anti-streptococcal antibodies: IgCH-linked effects on L chain expression.

L chains derived from anti-group A streptococcal carbohydrate antibodies raised in A/J, BALB/cJ, C57BL/6J, CB-20, BAB-14, and CAL-20 mice were examined by isoelectric focusing. Multiple strain-associated differences in the degree and frequency of expression of particular L chain spectrotypes were observed. Analysis of L chain-focusing patterns in allotype-congenic mice revealed that IgCH-linked genes can have profound effects on the L chain phenotypes expressed by strains with identical L chain genotypes. Lastly, the overall spectrotypic diversity of L chains from anti-GAC antibodies appears to be less extensive than the diversity of the antibodies from which these L chains derive, documented by similar techniques. These results are interpreted in light of the significance of combinatorial diversity in generating antibody heterogeneity.     

MHC and Non-MHC genetic influences on rous sarcoma metastasis in chickens

The B ⁵/B ⁵ genotype, in Leghorns, was associated with a high degree of metastasis of Rous sarcoma virus-induced tumors, but in combination with a Leghorn-New Hampshire background markedly less metastasis occurred. Initially, four mating types were used: B ⁵/B ⁵ × B ⁵/B ⁵ chickens from the F₅ generation of the cross of Leghorn lines 6₁ and 15₁, B ²⁴/B ²⁴ × B ²⁴/B ²⁴ chickens from line UNH 105 (New Hampshires), and reciprocal crosses of B ⁵/B ⁵ × B²⁴/B²⁴ chickens. Subsequently, F₂ generation progeny of the cross of B⁵/B⁵ and B ²⁴/B ²⁴ breeders, as well as B ²⁴/B ²⁴ line UNH 105 and B ⁵/B ⁵ (6₁ × 15₁)F₂ chickens, were used. Six-week-old chickens were inoculated in the wingweb with Rous sarcoma virus. Chickens dying during a 10-week period after inoculation were necropsied and suspect metastatic lesions examined histologically. Among 234 terminal chickens from the initial four mating types the incidence of metastasis associated with B ⁵/B ⁵ Leghorns (66%) was substantially higher than for B ²⁴/B ²⁴ New Hampshires (12%) and B ⁵/B ²⁴ progeny of reciprocal Leghorn-New Hampshire crosses (19 and 24%). Subsequently, among 524 terminal hosts in the Leghorn-New Hampshire F₂ population, B genotype significantly influenced tumor dissemination. However, among 52 concurrently challenged B ⁵/B ⁵ hosts from the (6₁ × 15₁)F₂ population the incidence of metastasis (60%) was significantly higher than among 122 B ⁵/B ⁵ hosts from the Leghorn-New Hampshire F₂ population (31%), indicating a non-major histocompatibility complex genetic effect on metastasis.     

流感病毒的检测和分型技术研究进展

近年来,病毒性流感的不断流行和暴发已引起世界范围的广泛关注。为了更好地对流感病毒进行检测和分型,我们对目前流感病毒常用的血清学检测和分型方法、免疫荧光法、PCR方法、多重RT-PCR法、实时RT-PCR法、依赖核酸序列的扩增法、环介导等温扩增法、焦磷酸测序法、基因芯片技术分别进行了描述,并阐述了其优缺点。     

Alloantigen system L affects the outcome of rous sarcomas

This study was designed to examine the alloantigen system L effects on Rous sarcomas in three B complex genotypes. The parental stock was 50% Modified Wisconsin Line 3 x White Leghorn Line NIU 4 and 50% inbred Line 6.15-5. Pedigree matings of two B(2)B(5) L(1)L(2) sires to five B(2)B(5) L(1)L(2) dams per sire produced experimental chicks segregating for B and L genotypes. Chicks were inoculated with 20 pock-forming units (pfu) of Rous sarcoma virus (RSV) at 6 weeks of age. Tumors were scored six times over 10 weeks postinoculation after which the tumor scores were used to assign a tumor profile index (TPI) to each chicken. Tumor growth over time and TPI were evaluated by repeated-measures analysis of variance and analysis of variance, respectively. Six trials were conducted with a total of 151 chickens. The major histocompatibility (B) complex affected the responses as the B(2)B(2) and B(2)B(5) genotypes had significantly lower tumor growth over time and TPI than the B(5)B(5) genotype. Separate analyses revealed no significant L system effect in B(2)B(2) or B(2)B(5) backgrounds. However, L genotype significantly affected (P < 0.05) both tumor growth over time and TPI in B(5)B(5) chickens. B(5)B(5) L(1)L(2) birds had TPI significantly lower than B(5)B(5) L(1)L(1) chickens but not B(5)B(5) L(2)L(2). Mortality was lower in the B(5)B(5) L(1)L(2) birds than in B(5)B(5) L(2)L(2) chickens. The L system, or one closely linked, affects the growth and ultimate outcome of Rous sarcomas. The response may depend upon the genetic background as well as MHC type.     

The autolytic enzyme LytA of Streptococcus pneumoniae is not responsible for releasing pneumolysin

It was previously proposed that autolysin's primary role in the virulence of pneumococci was to release pneumolysin to an extracellular location. This interpretation came into question when pneumolysin was observed to be released in significant amounts from some pneumococci during log-phase growth, because autolysis was not believed to occur at this time. We have reexamined this phenomenon in detail for one such strain, WU2. This study found that the extracellular release of pneumolysin from WU2 was not dependent on autolysin action. A mutant lacking autolysin showed the same pattern of pneumolysin release as the wild-type strain. Addition of mitomycin C to a growing WU2 culture did not induce lysis, indicating the absence of resident bacteriophages that could potentially harbor lytA-like genes. Furthermore, release of pneumolysin was unaltered by growth in 2% choline, a condition which is reported to inactivate autolysin, as well as most known pneumococcal phage lysins. Profiles of total proteins in the cytoplasm and in the supernatant media supported the hypothesis that release of pneumolysin is independent of pneumococcal lysis. Finally, under some infection conditions, mutations in pneumolysin and autolysin had different effects on virulence.     

Characterization of two distinct disulfide-linked B-G molecules in the chicken

Alloantisera specific for B-G antigens recognized a complex of molecules of apparent molecular weights of 90 and 98 Kd under nonreducing conditions and molecules of 40, 44, and 48 Kd under reducing conditions on both embryo- and adult-derived peripheral red blood cells (RBC). The chicken B-G molecules produced a unique two-dimensional "diagonal" pattern. Two antisera permitted the characterization of the complex B-G molecular profile as a homodimer composed of 48-Kd subunits and as a heterodimer composed of 40- and 44-Kd subunits. A rabbit antiserum produced against B-G molecules preferentially recognized the 48-Kd reduced molecules, suggesting that the 90-Kd molecule was a homodimer composed of two 48-Kd molecules. One B-G reagent was capable of recognizing only the 98-Kd nonreduced B-G molecule that gave rise to 40- and 44-Kd molecules under reducing conditions, suggesting that the 98-Kd molecule was a heterodimer composed of 44- and 40-Kd subunits. Adult chicken B-G2 molecules produced a variety of two-dimensional isoelectric focusing/sodium dodecyl sulfate-polyacrylamide gel electrophoresis (IEF/SDS-PAGE) patterns depending on the characteristics of the reagent employed in the immunoprecipitation. B-G molecules were immunoprecipitated from primitive and definitive chicken RBCs but not from any nonerythroid cells tested. B-G molecules were not expressed by avian erythroblastosis virus (AEV)-transformed erythroleukemia cells, nor were they induced to appear with butyric acid-induced erythroid differentiation.