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Seminal and histopathological alterations in bucks challenged with Mannheimia haemolytica serotype a2 and its LPS
Nur Amira Azhar1, Bura Thlama Paul2,3, Faez Firdaus Abdullah Jesse4,5
1Institute of Tropical Agriculture and Food Security, Universiti Putra Malaysia, UPM Serdang, 43400, Selangor, Malaysia.
Abstract:
Pneumonic mannheimiosis is a widespread respiratory bacterial disease of small ruminants caused by Mannheimia haemolytica serotype A2. The disease is known to affect the respiratory organs of infected animals, but its effect on other vital and reproductive organs has not been fully explored. Previous studies have demonstrated increased serum pro-inflammatory cytokine concentration post-challenge with M. haemolytica A2 and its LPS, indicating systemic inflammation in the host. This study determined the potential tissue changes and alterations of sperm parameters due to infection of M. haemolytica A2 and its LPS endotoxin. In this study, twelve experimental bucks were randomly assigned to three groups of four bucks each: group 1 (control group) were intranasally inoculated with 2 mL of PBS pH 7.0, group 2 received 2 mL of 1.2 × 109 CFU/mL M. haemolytica A2 intranasally, and group 3 received 2 mL of LPS extracted from 1.2 × 109 CFU/mL of M. haemolytica A2 intravenously. Semen samples were collected at pre-determined intervals using an electro-ejaculator and analysed immediately after collection. All experimental bucks were slaughtered via exsanguination on day 60 to collect their vital and reproductive organs at necropsy, and the samples were processed and analysed for histopathological changes. The current study has revealed that bucks challenged with M. haemolytica A2 and its LPS exhibited alterations in semen parameters such as motility, wave pattern, viability, and morphological abnormalities. Mild to moderate histopathological changes of the lung, liver, testis, epididymis, vas deferens, prostate, and lymph nodes were also observed in both challenged groups. Therefore, this study revealed the potential harmful effects of respiratory mannheimiosis on the reproductive organs of the infected bucks and sheds light on the expanse of systemic effects of this disease.
Insights
Pneumonic mannheimiosis caused by Mannheimia haemolytica A2 can harm buck reproductive health. This study found M. haemolytica A2 infection and its LPS endotoxin negatively impacted sperm quality and caused tissue damage in vital organs.
Area of Science:
- Veterinary Pathology
- Animal Reproduction
- Bacterial Disease Research
Background:
- Pneumonic mannheimiosis, caused by Mannheimia haemolytica serotype A2, is a significant respiratory disease in small ruminants.
- While respiratory effects are known, the impact of M. haemolytica A2 on reproductive organs and systemic tissues remains underexplored.
- Previous research indicates M. haemolytica A2 challenge induces systemic inflammation via pro-inflammatory cytokines.
Purpose of the Study:
- To investigate the effects of M. haemolytica A2 infection and its lipopolysaccharide (LPS) endotoxin on buck reproductive parameters.
- To determine potential histopathological changes in vital and reproductive organs following M. haemolytica A2 challenge.
- To elucidate the systemic impact of M. haemolytica A2 beyond the respiratory tract.
Main Methods:
- Twelve experimental bucks were divided into three groups: control (PBS), intranasal M. haemolytica A2 challenge, and intravenous M. haemolytica A2 LPS challenge.
- Semen samples were collected periodically via electro-ejaculation and analyzed for motility, viability, and morphology.
- Vital and reproductive organs were collected at necropsy on day 60 for histopathological examination.
Main Results:
- Bucks challenged with M. haemolytica A2 and its LPS exhibited significant alterations in sperm motility, wave pattern, viability, and increased morphological abnormalities.
- Mild to moderate histopathological lesions were observed in the lungs, liver, testes, epididymis, vas deferens, prostate, and lymph nodes of challenged bucks.
- Both intranasal M. haemolytica A2 and intravenous LPS administration led to comparable systemic and reproductive tissue damage.
Conclusions:
- Respiratory mannheimiosis caused by M. haemolytica A2 poses a significant threat to the reproductive capacity of infected bucks.
- The study highlights the systemic nature of M. haemolytica A2 infection, affecting multiple vital and reproductive organs.
- Findings underscore the importance of considering reproductive health implications in managing pneumonic mannheimiosis outbreaks.
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