Impact of sire selection and breed on parasite resistance in sheep

Treatment of COVID-19 with Chloroquine: Implication for Malaria Chemotherapy Using ACTs in Disease Endemic Countries

Journal of Tropical Pediatrics ◽

10.1093/tropej/fmaa089 ◽

2020 ◽

Author(s):

Neils Ben Quashie ◽

Nancy Odurowah Duah-Quashie

Keyword(s):

Intermittent Preventive Treatment ◽

Preventive Treatment ◽

World Health ◽

Cross Resistance ◽

Drug Resistant ◽

Combination Therapies ◽

Parasite Resistance ◽

Demand And Supply ◽

First Choice ◽

Health Organization

Abstract Based on reports of parasite resistance and on World Health Organization recommendation, chloroquine was replaced with the artemisinin-based combination therapies (ACTs) as the first choice of drugs for the treatment of uncomplicated malaria. Disuse of chloroquine led to restoration of drug-sensitive parasite to some extent in certain countries. Ever since chloroquine and hydroxychloroquine were touted as potential treatment for coronavirus disease 2019 (COVID-19), there has been a dramatic surge in demand for the drugs. Even in areas where chloroquine is proscribed, there has been an unexpected increase in demand and supply of the drug. This situation is quite worrying as the indiscriminate use of chloroquine may produce drug-resistant parasites which may impact negatively on the efficacy of amodiaquine due to cross-resistance. Amodiaquine is a partner drug in one of the ACTs and in some of the drugs used for intermittent preventive treatment. We herein discuss the consequences of the escalated use of chloroquine in the management of COVID-19 on chemotherapy or chemoprevention of malaria and offer an advice. We speculate that parasite strains resistant to chloroquine will escalate due to the increased and indiscriminate use of the drug and consequently lead to cross-resistance with amodiaquine which is present in some drug schemes aforementioned. Under the circumstance, the anticipated hope of reverting to the use of the ‘resurrected chloroquine’ to manage malaria in future is likely to diminish. The use of chloroquine and its derivatives for the management of COVID-19 should be controlled.

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Genetic importance of fat and eye muscle depth in Merino breeding programs

Animal Production Science ◽

10.1071/an14645 ◽

2016 ◽

Vol 56 (4) ◽

pp. 690 ◽

Cited By ~ 15

Author(s):

D. J. Brown ◽

A. A. Swan

Keyword(s):

Carcass Traits ◽

Genetic Correlations ◽

Fibre Diameter ◽

Economic Index ◽

Parasite Resistance ◽

Eye Muscle ◽

Breeding Programs ◽

Dual Purpose ◽

Internal Parasite ◽

Reproduction Traits

Australian Merino breeders have traditionally selected animals for breeding predominately on the basis of wool characteristics. Over recent decades, an increasing proportion of Merino breeders are interested in producing a ewe that can be used for prime-lamb production, but that also performs well for wool characteristics. Correlations between ultrasound carcass traits and other traits such as wool, internal parasite resistance and reproduction traits, are not very well known. The aims of this study were three-fold: (1) to estimate the genetic relationships between ultrasound carcass traits and wool, internal parasite resistance and reproduction traits, (2) to determine the value of recording ultrasound carcass traits in Merino breeding programs, and (3) to evaluate the impact of improving ewe genetic merit for fatness on their reproduction performance. Ultrasound fat and eye muscle depth had small to moderate genetic correlations with most traits, with positive correlations observed for bodyweight, fibre diameter, fibre curvature and reproduction, and negative correlations observed for fleece weight, fibre diameter coefficient of variation, worm egg count and breech wrinkle. As expected on the basis of these genetic correlations, estimated breeding values for fat depth of ewes had a positive association with their observed reproduction performance, but the effect explained only minimal variation in reproductive performance, and was extremely variable among flocks and years. A range of measurement scenarios was investigated for three standard MERINOSELECT indexes. Measuring fat and eye muscle depth resulted in 3%, 4% and 21% additional economic index gain for the fine, medium and dual purpose indexes, respectively, whereas measuring reproduction traits directly resulted in 17%, 27% and 45% additional gain in the economic index. Dual purpose index gains benefited more from measuring ultrasound carcass traits as it is the only index with a direct economic value placed on carcass traits. Measuring fat and eye muscle depth also resulted in a greater reduction in worm egg count. The results indicated that desirable genetic progress can be made in wool, ultrasound carcass, internal parasite resistance and number of lambs born and weaned simultaneously using multiple trait selection to account for the mix of favourable and unfavourable correlations between these traits. These results also demonstrated that the best method to maximise economic gain is to measure as many traits (or closely correlated traits) in the breeding objective as possible.

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The PCR typing of MHC-DRB genes in the sheep using primers for an intronic microsatellite: Application to nematode parasite resistance

Immunology and Cell Biology ◽

10.1038/icb.1996.59 ◽

1996 ◽

Vol 74 (4) ◽

pp. 330-336 ◽

Cited By ~ 28

Author(s):

PM OUTTERIDGE ◽

L ANDERSSON ◽

PGC DOUCH ◽

RS GREEN ◽

PS GWAKISA ◽

...

Keyword(s):

Nematode Parasite ◽

Parasite Resistance

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Effect of a diet high in energy and protein on growth, carcase characteristics and parasite resistance in goats

Tropical Animal Health and Production ◽

10.1007/s11250-006-4443-z ◽

2007 ◽

Vol 39 (1) ◽

pp. 59-70 ◽

Cited By ~ 26

Author(s):

V. Phengvichith ◽

I. Ledin

Keyword(s):

Parasite Resistance

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Cod courtship song: a song at the expense of dance?

Canadian Journal of Zoology ◽

10.1139/z99-010 ◽

1999 ◽

Vol 77 (4) ◽

pp. 542-550 ◽

Cited By ~ 40

Author(s):

Frode Engen ◽

Ivar Folstad

Keyword(s):

Mate Choice ◽

Gadus Morhua ◽

Reproductive Behaviour ◽

Courtship Song ◽

Sexually Dimorphic ◽

Individual Quality ◽

Allocation Of Resources ◽

Parasite Resistance ◽

Sperm Density ◽

Tentative Explanation

Sexually selected characters may reveal information about individual quality during mate choice. Fin display and sound emitted with the aid of specific drumming muscles are characters described as being of importance in the reproductive behaviour of cod (Gadus morhua L.). We examined whether the mass of drumming muscles or fin size was sexually dimorphic, and whether these characters could provide information about male cod that was potentially of benefit to mate-seeking females. The mass of drumming muscles, but not fin size, was sexually dimorphic, with males having larger muscles than females. Neither the mass of drumming muscles nor fin size apparently revealed information about traits that may be associated with parasite resistance in males (i.e., parasite intensities and leukocyte densities). However, variation in fertilization potential (i.e., spermatocrit level) among males was related to both mass of drumming muscles and fin size. Thus, by evaluating sound and fin size, mate-seeking females may obtain information about fertilization ability among males. This may be of particular importance for females in a species whose eggs commonly remain unfertilized. Furthermore, males with large drumming muscles and small fins had low spermatocrit levels. This may reflect reductions in sperm density resulting from frequent ejaculations by attractive males. A costly allocation of resources for the development of drumming muscles at the expense of fin muscles used for propulsion is presented as a tentative explanation as to why females should pay attention to these particular traits during courtship. Increased investment in "song" may thus appear at the expense of "dance."

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PSVIII-10 Genome-wide CNV analysis unravels a deletion associated with parasite resistance in Florida native sheep

Journal of Animal Science ◽

10.1093/jas/skab235.444 ◽

2021 ◽

Vol 99 (Supplement_3) ◽

pp. 243-244

Author(s):

Brittany N Diehl ◽

Andres A Pech-Cervantes ◽

Thomas H Terrill ◽

Ibukun M Ogunade ◽

Owen Rae ◽

...

Keyword(s):

Copy Number ◽

Association Studies ◽

Chromosome 21 ◽

Trend Test ◽

P Value ◽

Genome Wide Association Studies ◽

Parasite Resistance ◽

Association Testing ◽

Genome Wide ◽

Native Sheep

Abstract Florida Native sheep is an indigenous breed from Florida and expresses superior parasite resistance. Previous candidate and genome wide association studies with Florida Native sheep have identified single nucleotide polymorphisms with additive and non-additive effects associated with parasite resistance. However, the role of other potential DNA variants, such as copy number variants (CNVs), controlling this complex trait have not been evaluated. The objective of the present study was to investigate the importance of CNVs on resistance to natural Haemonchus contortus infections in Florida Native sheep. A total of 200 sheep were evaluated in the present study. Phenotypic records included fecal egg count (FEC, eggs/gram), FAMACHA score, and packed cell volume (PCV, %). Sheep were genotyped using the GGP Ovine 50K SNP chip. The copy number analysis was used to identify CNVs using the univariate method. A total of 170 animals with CNVs and phenotypic data were used for the association testing. Association tests were carried out using single linear regression and Principal Component Analysis (PCA) correction to identify CNVs associated with FEC, FAMACHA, and PCV. To confirm our results, a second association testing using the correlation-trend test with PCA correction was performed. Significant CNVs were detected when their adjusted p-value was < 0.05 after FDR correction. A deletion CNV in chromosome 21 was associated with FEC. This DNA variant was located in intron 2 of RAB3IL gene and overlapped a QTL associated with changes in eosinophil number. Our study demonstrated for the first time that CNVs could be potentially involved with parasite resistance in this heritage sheep breed.

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Antimalarial activity of the bisquinoline trans-N1,N2-bis (7-chloroquinolin-4-yl)cyclohexane-1,2-diamine: comparison of two stereoisomers and detailed evaluation of the S,S enantiomer, Ro 47-7737.

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.41.3.677 ◽

1997 ◽

Vol 41 (3) ◽

pp. 677-686 ◽

Cited By ~ 44

Author(s):

R G Ridley ◽

H Matile ◽

C Jaquet ◽

A Dorn ◽

W Hofheinz ◽

...

Keyword(s):

Antimalarial Activity ◽

Ex Vivo ◽

The Other ◽

Parasite Resistance ◽

Curative Effect ◽

Specific Process ◽

Terminal Half Life ◽

Detailed Evaluation ◽

Oral Doses

The S,S enantiomer of the bisquinoline trans-N1,N2-bis(7-chloroquinolin-4-yl)cyclohexane-1,2-diamine, Ro 47-7737, is significantly more potent against chloroquine-resistant Plasmodium falciparum than the R,R enantiomer and the previously described racemate. Both the enantiomers and the racemate are more potent inhibitors of heme polymerization than chloroquine, and their activities are probably mediated by inhibition of this parasite-specific process. The S,S enantiomer, Ro 47-7737, was studied in more detail and proved to be a potent antimalarial in the treatment of P. vivax ex vivo and P. berghei in vivo. Its suppression of P. berghei growth in a mouse model (50% effective dose, 2.3 mg/kg of body weight) was equal to that of chloroquine and mefloquine, and Ro 47-7737 was found to be more potent than these two drugs in the Rane test, in which the curative effect of a single dose is monitored. The dose at which 50% of animals were permanently cured (34 mg/kg) was markedly superior to those of chloroquine (285 mg/kg) and mefloquine (> 250 mg/kg). When administered orally at 50 mg/kg, Ro 47-7737 also showed a faster clearance of parasites than either chloroquine or mefloquine, and unlike the other two compounds, Ro 47-7737 showed no recrudescence. In a study to compare prophylactic efficacies of oral doses of 50 mg/kg, Ro 47-7737 provided protection for 14 days compared to 3 days for mefloquine and 1 day for chloroquine. The good curative and prophylactic properties of the compound can be explained in part by its long terminal half-life. The ability to generate parasite resistance to Ro 47-7737 was also assessed. With a rodent model, resistance could be generated over eight passages. This rate of resistance generation is comparable to that of mefloquine, which has proved to be an effective antimalarial for many years. Toxicity liabilities, however, ruled out this compound as a candidate for drug development.

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