Seroprevalence, and molecular detection of Brucella abortus in cattle tissues from an abattoir in Namibia

Figures & data

Figure 1. Map of Namibia showing the location of the Khomas region in the central part of the country.

Table 1. Oligonucleotide sequences of primers that were used in the AMOS-PCR assay to detect the Brucella species and the expected sizes of amplicons.

Name of primer	Sequence (5′-3′)	Size of amplicon (bp)
B. abortus	GAC GAA CGG AAT TTT TCC AAT CCC	498
B. melitensis	AAA TCG CGT CCT TGC TGG TCT GA	731
B. ovis	CGG GTT CTG GCA CCA TCG TCG GG	976
B. suis	GCG CGG TTT TCT GAA GGT GGT TCA	285
IS711	TGC CGA TCA CTT AAG GGC CTT CAT

Table 2. Characteristics of the seropositive cattle (n = 7), and results of serological, ITS-PCR (on tissues and cultures) and AMOS-PCR (cultures) screening (Identity numbers (ID No. correspond with ID No. in Figure 2)).

Age (years)	Sex (M/F)	History of movement	RBT (±)	CFT titre (ICFTU/ml)	ITS-PCR on tissues (±)		ITS-PCR on cultures (±)		AMOS-PCR on cultures (±)
					Lymph nodes (ID No.)	Spleen (ID No.)	Lymph nodes (ID No.)	Spleen (ID No.)	Lymph nodes (ID No.)	Spleen (ID No.)
≥5	F	Stayed on one farm throughout	+	120 (+)	- (1)	- (8)	- (1)	+ (8)	- (1)	+ (8)
2–2.5	M	Stayed on one farm throughout	+	30 (+)	+ (2)	+ (9)	+ (2)	+ (9)	+ (2)	+ (9)
2–2.5	M	Stayed on two farms and moved through one auction	+	30 (+)	+ (3)	+ (10)	+ (3)	+ (10)	+ (3)	+ (10)
4	M	Stayed on one farm throughout	+	60 (+)	+ (4)	+ (11)	+ (4)	+ (11)	+ (4)	+ (11)
≥5	M	Moved through two farms and two auctions	+	120 (+)	+ (5)	+ (12)	+ (5)	+ (12)	+ (5)	+ (12)
≥5	M	Moved through two farms and two auctions	+	18 (-)	+ (6)	+ (13)	- (6)	+ (13)	- (6)	+ (13)
≥5	F	Stayed on one farm throughout	+	18 (-)	+ (7)	+ (14)	- (7)	- (14)	- (7)	- (14)

NOTE: ID No.: identification number of the tissue examined.

Figure 2. Genus-specific 16S-23S rRNA interspacer region (ITS) PCR amplification gel electrophoresis results of tissue samples (lymph nodes and spleen) from seropositive cattle. Lane L (100 bp marker), Lane 1–7 (lymph nodes), Lane 8–14 (spleen), Lane 15 (positive control: B. melitensis Rev 1), Lane 16 (negative control: nuclease-free water).

Figure 3. AMOS-PCR products from the amplification of the IS711 gene using Brucella species‐specific primers. Lane L (100 bp marker), Lane 1–6 (spleen), Lane 7–10 (lymph nodes), Lane 11 (B. abortus RB51- positive control), Lane 12 (negative control: nuclease free water).

Figure 4. BaSS-PCR products showing the amplification of a 500 bp B. abortus IS711 specific element product in the alkB locus, and a 180 bp eryCD locus product that is common to all Brucella except B. abortus S19 strains. Lane L1-L7 - lymph nodes, Lane S1-S7 - spleen, thereafter, positive, and negative controls.

Table 3. A comparison of assay agreement levels on various samples obtained from seropositive cattle (n = 7) (extracted from Table 2).

Assays	Number of test results in agreement	Agreement (%)
RBT and CFT	5	71.4
RBT and ITS-PCR (tissues)	6	85.7
RBT and ITS-PCR (cultures)	6	85.7
RBT and AMOS-PCR (cultures)	6	85.7
CFT and ITS-PCR (tissues)	4	57.1
CFT and ITS-PCR (cultures)	6	85.7
CFT and AMOS-PCR (cultures)	6	85.7
ITS-PCR (tissues) and ITS-PCR (cultures)	6	85.7
ITS-PCR (tissues) and AMOS-PCR (cultures)	6	85.7

Discussion.

Data availability statement

The datasets used and/or analysed during the current study are included in this manuscript.