Pathogenicity and molecular characterization of Mycoplasma bovis isolate from calves in Morocco.

Bovine respiratory disease caused by Mycoplasma bovis (M. bovis) represents a major health problem for cattle worldwide that causes considerable financial losses. This study reports for the first time the molecular and pathogenic characterization of a strain of M. bovis isolated from a dead local calf with respiratory symptoms in Morocco. M. bovis was isolated from lung tissue, purified by cloning, and subtyped using MLST analysis. Experimental infection was conducted in naïve calves to evaluate pathogenicity. The isolate was identified as a new subtype ST-204 that shares similarities with the 2019-2021 Spanish strains (ST-169, ST-170, ST-171) and the 2018 Algeria isolate (ST-4). Experimental infection resulted in fever and respiratory symptoms with serous nasal discharge. At postmortem, lung lesions of congestion and hepatization were observed with lymph node enlargement and foci of necrosis. The study confirms the high pathogenicity of the isolate and the important role of M. bovis in bovine respiratory disease.

Comparative protection of small ruminants against Mannheimia haemolytica infection by inactivated bacterin and toxoid vaccines.

Background and Aim: Mannheimia haemolytica causes respiratory infection and mortality in sheep and goats, similar to the effects in cattle, which causes major economic damage. Regular vaccinations alongside good management practices remain the most efficient tools for controlling this disease. Indeed, vaccines against pasteurellosis are available, but results on their efficacy have varied. Therefore, this study aimed to evaluate the efficacy of three vaccines against mannheimiosis in small ruminants. Materials and Methods: We evaluated three vaccines developed from a local field isolate based on the inactivated bacterium, its toxoid, and a mixture of bacterin/toxoid, which we then tested on sheep and goats. Selected criteria that were evaluated were safety, antibody response, and protection through a challenge. Post-vaccination monitoring was carried out by enzyme-linked immunosorbent assay. The evaluation was based on antibody responses to vaccination in sheep and goats for both bacteria and leukotoxin. Protection was assessed by clinical and lesion scores after the challenge of vaccinated goats with a pathogenic strain. Results: The three tested vaccines were completely safe, did not cause any adverse reactions, and induced significant antibody titers in immunized animals. Following M. haemolytica challenge, unvaccinated goats showed clinical signs with lesions typical of the disease. Meanwhile, the best protection was obtained with the inactivated combined bacterin/toxoid vaccine. Conclusion: This study highlighted the effectiveness of adding a bacterial toxoid in the vaccine as a promising solution for preventing mannheimiosis in small ruminants. Because of the worldwide distribution of M. haemolytica infection, general prophylaxis based on a combined inactivated vaccine could greatly benefit.

Biological and molecular characterization of a sheep pathogen isolate of Mannheimia haemolytica and leukotoxin production kinetics.

BACKGROUND AND AIM: Mannheimia haemolytica (Mha) is a common agent of pneumonia in ruminants globally, causing economic losses by morbidity, mortality, and treatment costs. Infection by Mha is often associated with or promoted by respiratory viral pathogens and environmental conditions. Infections due to Mha have rarely been described in small ruminants. This study reports the biological and molecular characteristics of a new Moroccan Mha isolate from small ruminants presenting typical respiratory symptoms. We also studied the cultural parameters, growth kinetics, and Lkt excretion of the isolate and its pathogenicity on laboratory animals and small ruminants. MATERIALS AND METHODS: Suspected pasteurellosis cases in sheep and goat flocks in Morocco were investigated. A local strain of Mha was isolated and identified using biochemical and molecular methods. Polymerase chain reaction-targeting specific genes were used for serotyping and phylogenetic analyses; further, leukotoxin production, cytotoxicity, and pathogenicity of the isolate in mice, goats, and sheep were investigated. RESULTS: Phylogeny analysis revealed 98.76% sequence identity with the USA isolate of 2013; the strain growth with a cycle of 9-10 h with leukotoxin secretion was detected by NETosis and quantified by cytotoxicity and mortality of mice. Goat and sheep infections cause hyperthermia, with characteristic postmortem lesions in the trachea and lung. CONCLUSION: A local isolate of Mha from sheep that died of pneumonia was characterized for the 1st time in North Africa using biological and molecular methods. Although growth on appropriate culture media is accompanied by intense leukotoxin secretion, experimental infections of sheep and goats cause hyperthermia and typical lesions of pneumonia.

Investigation of Post Vaccination Reactions of Two Live Attenuated Vaccines against Lumpy Skin Disease of Cattle.

Lumpy skin disease virus (LSDV) causes an economically important disease in cattle. The only method for successful control is early diagnosis and efficient vaccination. Adverse effects of vaccination such as local inflammation at the injection site and localized or generalized skin lesions in some vaccinated animals have been reported with live vaccines. The aim of this work was to compare the safety of two lumpy skin disease (LSD) vaccine strains, Kenyan (Kn) Sheep and Goat Pox (KSGP O-240) and LSDV Neethling (Nt) strain, and to determine the etiology of the post-vaccination (pv) reactions observed in cattle. Experimental cattle were vaccinated under controlled conditions with Nt- and KSGP O-240-based vaccines, using two different doses, and animals were observed for 3 months for any adverse reactions. Three out of 45 cattle vaccinated with LSDV Nt strain (6.7%) and three out of 24 cattle vaccinated with Kn strain (12.5%) presented LSD-like skin nodules, providing evidence that the post-vaccination lesions may not be strain-dependent. Lesions appeared 1-3 weeks after vaccination and were localized in the neck or covering the whole body. Animals recovered after 3 weeks. There is a positive correlation between the vaccine dose and the appearance of skin lesions in vaccinated animals; at the 105 dose, 12% of the animals reacted versus 3.7% at the 104 dose. Both strains induced solid immunity when protection was measured by neutralizing antibody seroconversion.

Experimental evaluation of the cross-protection between Sheeppox and bovine Lumpy skin vaccines.

The Capripoxvirus genus includes three agents: Sheeppox virus, Goatpox virus and Lumpy skin disease virus. Related diseases are of economic importance and present a major constraint to animals and animal products trade in addition to mortality and morbidity. Attenuated vaccines against these diseases are available, but afforded cross-protection is controversial in each specie. In this study, groups of sheep, goats and cattle were vaccinated with Romania SPPV vaccine and challenged with corresponding virulent strains. Sheep and cattle were also vaccinated with Neethling LSDV vaccine and challenged with both virulent SPPV and LSDV strains. Animals were monitored by clinical observation, rectal temperature as well as serological response. The study showed that sheep and goats vaccinated with Romania SPPV vaccine were fully protected against challenge with virulent SPPV and GTPV strains, respectively. However, small ruminants vaccinated with LSDV Neethling vaccine showed only partial protection against challenge with virulent SPPV strain. Cattle showed also only partial protection when vaccinated with Romania SPPV and were fully protected with Neethling LSDV vaccine. This study showed that SPPV and GTPV vaccines are closely related with cross-protection, while LSDV protects only cattle against the corresponding disease, which suggests that vaccination against LSDV should be carried out with homologous strain.

Development and Evaluation of an Inactivated Lumpy Skin Disease Vaccine for Cattle.

Lumpy skin disease (LSD) of cattle is caused by a virus within Capripoxvirus genus. It leads to huge economic losses in addition to trade and animal movement limitation. Vaccination is the only economically feasible way to control this vector-borne disease. Only live attenuated vaccines have been used so far and no inactivated vaccine has been developed nor tested in cattle. In this study, we developed an inactivated oily adjuvanted vaccine based on Neethling strain and tested it on cattle. Selected criteria of appreciation were safety, antibody response by Virus Neutralization and protection through challenge. A field trial was also performed in Bulgaria. The vaccine was safe and did not cause any adverse reaction, high level of specific antibodies was obtained starting from day 7 post-vaccination and protection against virulent challenge strain that caused typical disease in control animals was total. Induced protection was similar to that obtained with live vaccine, without any adverse effect. In addition, the field study confirmed safety and efficacy of the vaccine, which did not show any adverse reaction and induced a high level of antibodies for up to one year. General prophylaxis based on inactivated vaccine could be of great benefit in endemic countries or at risk regions.

Co-infections of chickens with avian influenza virus H9N2 and Moroccan Italy 02 infectious bronchitis virus: effect on pathogenesis and protection conferred by different vaccination programmes.

Since the emergence of low pathogenic avian influenza (LPAI) H9N2 viruses in Morocco in 2016, severe respiratory problems have been encountered in the field. Infectious bronchitis virus (IBV) is often detected together with H9N2, suggesting disease exacerbation in cases of co-infections. This hypothesis was therefore tested and confirmed in laboratory conditions using specific-pathogen-free chickens. Most common field vaccine programmes were then tested to compare their efficacies against these two co-infecting agents. IBV γCoV/chicken/Morocco/I38/2014 (Mor-IT02) and LPAI virus A/chicken/Morocco/SF1/2016 (Mor-H9N2) were thus inoculated to commercial chickens. We showed that vaccination with two heterologous IBV vaccines (H120 at day one and 4/91 at day 14 of age) reduced the severity of clinical signs as well as macroscopic lesions after simultaneous experimental challenge. In addition, LPAI H9N2 vaccination was more efficient at day 7 than at day 1 in limiting disease post simultaneous challenge.RESEARCH HIGHLIGHTS Simultaneous challenge with IBV and AIV H9N2 induced higher pathogenicity in SPF birds than inoculation with IBV or AIV H9N2 alone.Recommended vaccination programme in commercial broilers to counter Mor-IT02 IBV and LPAIV H9N2 simultaneous infections: IB live vaccine H120 (d1), AIV H9N2 inactivated vaccine (d7), IB live vaccine 4-91 (d14).

Identification of Eilat virus and prevalence of infection among Culex pipiens L. populations, Morocco, 2016.

Eilat virus (EILV) is described as one of the few alphaviruses restricted to insects. We report the record of a nearly-complete sequence of an alphavirus genome showing 95% identity with EILV during a metagenomic analysis performed on 1488 unblood-fed females and 1076 larvae of the mosquito Culex pipiens captured in Rabat (Morocco). Genetic distance and phylogenetic analyses placed the EILV-Morocco as a variant of EILV. The observed infection rates in both larvae and adults suggested an active circulation of the virus in Rabat and its maintenance in the environment either through vertical transmission or through horizontal infection of larvae in breeding sites. This is the first report of EILV out of Israel and in Culex pipiens populations.

Use of FTA® card methodology for sampling and molecular characterization of Echinococcus granulosus sensu lato in Africa.

Cystic Echinococcosis is a parasitic disease caused by the cestode Echinococcus granulosus widely distributed in Africa. Monitoring of this parasite requires access to cyst samples on intermediate hosts observed at the slaughterhouse. In order to facilitate sampling in the field and analysis, the French National Reference Laboratory for Echinococcus spp. has developed a tissue derived from DNA sampling with FTA® card technology. The DNA samples were taken by applying the FTA® paper on the germinal layer after opening the cysts. The sampling technique was validated using frozen cysts (n = 76) stored in the laboratory and from field samples (n = 134) taken at the slaughterhouse by veterinarian technicians during meat inspection in Morocco, Mali and Mauritania. DNA was extracted after several weeks of storage at room temperature. PCR assays were performed using primers for generic cestode (cox1) and amplified fragments were sequenced. All samples taken in the lab and 80% of field samples were capable of molecular characterization. Cyst-derived DNA from FTA® samples can be useful for easy sampling, storage and rapid, safe and cheap shipment. The use of the FTA methodology will facilitate studies in the field to investigate the presence and genetic characterization of E. granulosus sensu lato in African countries.

Efficacy of Massachusetts and 793B Vaccines Against Infectious Bronchitis Moroccan-Italy 02 Virus in Specific-Pathogen-Free Chickens and Commercial Broilers.

The ability of commercial vaccines H120 and 4/91 to protect against Moroccan-Italy 02 infectious bronchitis virus (Mor-It02) was investigated in specific-pathogen-free (SPF) chickens and commercial broiler chickens. Commercial broiler chicks (Experiment 1) were vaccinated at the hatchery with H120 vaccine at Day 1, and challenged at Day 21 with 104 50% egg-infective dose (EID50) of Mor-It02. All chicks were observed daily for clinical signs attributable to Mor-It02 infection during the 10 days postchallenge (pc). At 5 and 10 days pc, chicks were humanely sacrificed for necropsy examination, and tissues were collected for histopathology evaluation. To better understand the findings on commercial broilers, day-old SPF chicks were divided into five groups in a second experiment: Group Mass/4-91, vaccinated with H120 and 4/91 respectively at Days 1 and 15 of age; Group Mass/Mass, vaccinated by H120 at Days 1 and 15; Group Mass, vaccinated with H120 at Day 1; Group NV, kept unvaccinated; and Group NC, kept as a negative control (unchallenged). At Day 24 of age, Groups Mass/4-91, Mass/Mass, Mass, and NV were challenged with 104 EID50 of Mor-It02. In both experiments, blood samples were collected at different periods for serologic analyses. Oropharyngeal swabs were collected for virus detection by reverse-transcription PCR. In Experiments 1 and 2, respiratory signs started as early as 24 hr pc and maximum severity was observed on Days 3 and 4 pc. The viral shedding rate was significantly lower in Group Mass/4-91 compared to other challenged groups. Serologic analysis in both experiments showed that the sera of challenged group exhibited significantly higher antibody titers than sera collected before challenge. Histopathologic investigations in SPF birds showed deciliation and hyperplasia in Group NV and less-pronounced lesions in Groups Mass/Mass and Mass. In commercial broilers vaccinated with H120 alone, hyperplasia and deciliation were observed in 90% of the tracheas. These experiments illustrated that Mor-It02 is pathogenic for chickens and a combination of live H120 and 4/91 vaccines given respectively at Day 1 and Day 15 of age confer a good protection against Mor-It02.