Experimental exposure of llamas (Lama glama) to Brucella abortus: humoral antibody response

False Positives in Brucellosis Serology: Wrong Bait and Wrong Pond?

This review summarizes the status of resolving the problem of false positive serologic results (FPSR) in Brucella serology, compiles our knowledge on the molecular background of the problem, and highlights some prospects for its resolution. The molecular basis of the FPSRs is reviewed through analyzing the components of the cell wall of Gram-negative bacteria, especially the surface lipopolysaccharide (LPS) with details related to brucellae. After evaluating the efforts that have been made to solve target specificity problems of serologic tests, the following conclusions can be drawn: (i) resolving the FPSR problem requires a deeper understanding than we currently possess, both of Brucella immunology and of the current serology tests; (ii) the practical solutions will be as expensive as the related research; and (iii) the root cause of FPSRs is the application of the same type of antigen (S-type LPS) in the currently approved tests. Thus, new approaches are necessary to resolve the problems stemming from FPSR. Such approaches suggested by this paper are: (i) the application of antigens from R-type bacteria; or (ii) the further development of specific brucellin-based skin tests; or (iii) the application of microbial cell-free DNA as analyte, whose approach is detailed in this paper.

Detection of Anti‐BrucellaAntibodies in Llama (Lama glama)

Seven llamas were immunized with killed Brucella abortus S1119.3 cells and bled sequentially, resulting in 64 samples. An eighth llama was kept as a negative control. In addition, 299 llama and 2075 alpaca sera, submitted for diagnostic testing, were included. Sera from all llamas were tested by the buffered antigen plate agglutination test, the complement fixation test, and the indirect enzyme immunoassays using smooth and rough lipopolysaccharides. A competitive enzyme immunoassay and fluorescence polarization assays were also performed. The sensitivity values for llama sera ranged from 92.2% to 100% and the specificity values from 89.6% to 100%. No alpacas were immunized. The specificity values for alpaca sera ranged from 94.8% to 100% specific although some sera gave an 'agglutination like' reaction after about 10 minutes of incubation. The complement fixation test could not be used, as 31% of the sera were anticomplementary and 4% were false positive.

Quantification of llama inflammatory cytokine mRNAs by real-time RT-PCR

We have developed a method by which llama cytokine mRNAs can be quantified using real-time reverse transcription polymerase chain reaction (RT-PCR). Total RNA was extracted from lipopolysaccharide (LPS)-stimulated peripheral blood mononuclear cells (PBMCs) of llama, reverse transcribed to cDNA, and cytokine profiles for interleukin (IL)-1alpha, IL-1beta, IL-6 and tumor necrosis factor (TNF) alpha were quantified by real-time PCR. The expressions of mRNAs of inflammatory cytokines IL-1alpha, IL-1beta, IL-6 and TNFalpha were upregulated upon stimulation with LPS in a dose- and time-dependent manner. Incubation of PBMCs with 100 and 1,000 pg/ml of LPS for 3 to 6 hr resulted in the acceleration of the mRNA levels of inflammatory cytokines. Here, we describe a highly sensitive and reproducible method to quantify the transcription of llama cytokine mRNAs by real-time RT-PCR with the double-stranded DNA-binding dye SYBR Green I.

Cloning and sequence analysis of llama cytokines related to cell-mediated immunity

In order to characterize the T helper 1 (Th1) cytokines of llama, we have cloned several llama cytokine genes and compared them to those of other mammalian species. The cDNAs encoding for interleukin (IL)-2, interferon (IFN), IL-12p35 and IL-12p40 were amplified using specific primers designed from reported sequences of bovine cytokine genes. The cDNAs for llama IL-2, IFN-, IL-12 p35 and IL-12p40 were found to be 465, 501, 669 or 993 bp in length, with open reading frames encoding 154, 166, 222 or 330 amino acids, respectively. Homology analyses of nucleotide and deduced amino sequences of llama IL-2, IFN-, IL-12p35 and IL-12p40 and phylogenetic analysis based on their nucleotide sequences indicated the close relationship in these cytokine genes between llama and eutherian mammalian order Artiodactyla, which includes pig and cattle.

Cloning and sequence analysis of llama cytokines related to cell-mediated immunity

In order to characterize the T helper 1 (Th1) cytokines of llama, we have cloned several llama cytokine genes and compared them to those of other mammalian species. The cDNAs encoding for interleukin (IL)-2, interferon (IFN)gamma, IL-12p35 and IL-12p40 were amplified using specific primers designed from reported sequences of bovine cytokine genes. The cDNAs for llama IL-2, IFN-gamma, IL-12 p35 and IL-12p40 were found to be 465, 501, 669 or 993 bp in length, with open reading frames encoding 154, 166, 222 or 330 amino acids, respectively. Homology analyses of nucleotide and deduced amino sequences of llama IL-2, IFN-gamma, IL-12p35 and IL-12p40 and phylogenetic analysis based on their nucleotide sequences indicated the close relationship in these cytokine genes between llama and eutherian mammalian order Artiodactyla, which includes pig and cattle.