Biology subjects

Changula, K.

Publications and source records attributed to Changula, K..

5 recordsLinked to original sources

bioRxiv2026

Novel African Rhinolophus bat ACE2 sequences reveal the determinants of Afro-Eurasian sarbecovirus entry

Sarbecoviruses, including SARS-CoV and SARS-CoV-2, are frequently linked to Rhinolophus bats as their putative natural reservoirs. Angiotensin-converting enzyme 2 (ACE2), a host carboxypeptidase widely expressed in mammalian tissues, plays a critical role in sarbecovirus infection by serving as the cellular receptor for the viral spike (S) protein. Given recent human outbreaks and pandemics caused by members of sarbecoviruses, and the wide distribution of Rhinolophus bats, it is essential to maintain surveillance of these viruses while improving our understanding of their interactions with bat hosts, particularly the ACE2 receptor. However, while Rhinolophus bats from Asia have been relatively well studied, African Rhinolophus bats remain underrepresented and require further investigation. In this study, five Rhinolophus bat lung samples were obtained from Zambia, and ACE2 genes from these individuals were cloned and sequenced. We further evaluated the susceptibility of ACE2 variants to a panel of sarbecoviruses, revealing key residues that influence viral infectivity. ACE2 polymorphism was observed among Rhinolophus simulator individuals, revealing multiple ACE2 genotypes within the sampled population. However, R. simulator ACE2s did not permit infection by the clade 3 Afro-Eurasian sarbecoviruses tested in this study. Notably, RhGB01 and BM48-31 virus utilized only Rhinolophus blasii ACE2. Mutational analyses further suggested that ACE2 residues 31 and 41 play important roles in modulating spike-ACE2 interactions. This study reports 4 unique ACE2 sequences of R. simulator and R. blasii, and provides new insights into the molecular interactions between African Rhinolophus species ACE2s and the S protein of sarbecoviruses circulating in Africa and Europe. ImportanceAs putative natural reservoirs of sarbecoviruses, including SARS-CoV and SARS-CoV-2, Rhinolophus bats play a critical role in the emergence of zoonotic coronaviruses, making it essential to understand their interactions with these viruses for future pandemic preparedness. While Asian Rhinolophus bats have been relatively well studied, African species remain underrepresented, highlighting the need for further investigation. In this study, we cloned and sequenced ACE2 genes of five Rhinolophus bats collected in Zambia, Africa. We identified ACE2 polymorphism among Rhinolophus simulator individuals, although this variation was not associated with susceptibility to the clade 3 Afro-Eurasian sarbecoviruses examined. In addition, we identified key ACE2 residues that govern SARS-CoV-2 spike-ACE2 interactions and contribute to distinct infectivity patterns across species. These findings expand our understanding of the molecular determinants of sarbecovirus host range and support improved surveillance and risk assessment of emerging coronaviruses.

microbiology↗

bioRxiv2025

Antibiotic Use and Resistance in Zambia's Aquaculture Sector: Assessing Knowledge, Attitudes, and Practices Among Fish Farmers

Aquaculture in Zambia is rapidly growing, contributing significantly to food security and income generation. However, the intensification of fish farming raises concerns about antimicrobial use (AMU) and the emergence of antimicrobial resistance (AMR). This study assessed the knowledge, attitudes, and practices (KAP) of fish farmers regarding AMU and AMR across 25 districts in Zambias ten provinces. Data were collected from fish farmers using a structured questionnaire distributed via district fisheries officers and analyzed through descriptive and inferential statistics, including logistic regression. The results revealed significant gaps in knowledge, with only 17.4% of farmers classified as knowledgeable about AMU and AMR. Attitude assessments showed that 60.5% exhibited positive attitudes toward responsible AMU practices, while the remaining 39.5% displayed negative perceptions. In terms of practices, 76.5% adhered to good practices, including consulting veterinary professionals and responsible antibiotic use, whereas 23.5% engaged in poor practices. Key factors influencing KAP outcomes included age, farming experience, and annual production capacity. Farmers aged 30-39 years and those with 1-5 years of experience demonstrated significantly more positive attitudes (p < 0.05), while those with higher production capacities (501-1000 kg) exhibited better practices (p < 0.001). The findings highlight critical knowledge gaps and inconsistent practices regarding AMU and AMR among Zambian fish farmers. Targeted interventions, including education programs, enhanced access to veterinary services, and strengthened regulatory frameworks, are essential to promote responsible AMU, mitigate AMR risks, and ensure the sustainability of aquaculture in Zambia.

scientific communication and education↗

bioRxiv2025

Experimental Bacterial Co-infection in Nile Tilapia Shows High Pathogenicity from Lake Kariba Isolates

ObjectiveThis study aimed to determine the pathogenicity of bacteria (Aeromonas spp., Lactococcus garvieae, Acinetobacter spp., and Klebsiella spp.) isolated from Nile tilapia (Oreochromis niloticus) in small-scale aquaculture establishments on Lake Kariba through experimental infections. Materials and methodsHealthy fish (50g {+/-} 5g) were distributed among six transparent fish tanks labeled A to F. Fish in tanks A, B, C, and D were exposed to Aeromonas spp., Lactococcus garvieae, Acinetobacter spp., and Klebsiella spp., respectively, through intraperitoneal inoculation. Tank E received a co-infection of all isolates, while tank F served as the control group with an injection of normal saline. Clinical signs, mortalities and post-mortem lesions were recorded in all experimental groups, with histopathological examinations performed on liver, kidney, and spleen tissues. ResultsThe findings indicate that Acinetobacter spp. and Klebsiella spp. exhibit low pathogenicity, evidenced by few clinical signs such as lethargy, pale skin, and fin erosion. The study further highlighted Aeromonas spp. and Lactococcus garvieae as the bacterial isolates causing significant clinical symptoms in Nile tilapia compared to Acinetobacter spp. and Klebsiella spp. following experimental infection. ConclusionCo-infection with all bacterial pathogens demonstrated very high pathogenicity, with 100% mortality reported within seven days post-infection. The study proposes the development of a polyvalent vaccine to control fish disease outbreaks in small-scale aquaculture operations on Lake Kariba, thereby sustaining aquaculture production in Zambia.

microbiology↗

bioRxiv2025

Global Distribution of Coronaviruses among Bat Populations detected using Molecular techniques, A Systematic Review

Surveillance of bat coronaviruses (CoVs) is of public health importance, as accumulating evidence suggests that bats are hosts of the three significant pandemic viruses, namely Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV), Middle East Respiratory Syndrome Coronavirus (MERS-CoV), and SARS-CoV-2. Studies focused on identifying different species of bat CoVs may have information cardinal for effective prevention and control of emerging zoonotic diseases. We conducted a systematic review using selected keywords (Surveillance, detection, identification, discovery, isolation, characterization, molecular methods, and Bat coronaviruses) to evaluate molecular studies on CoVs in bats. A total of 790 articles were found using the advanced search strategy of the PubMed database. Following the selection criteria, a total of 127 articles were finally chosen for full-text evaluation. Out of the total of 54 countries examined, China emerged as the country with the highest number of studies, accounting for 26% (n = 33). The sample categories consisted of faecal, urine, guano, blood, tissues, oral, and rectal swabs. The molecular detection approaches included polymerase chain reaction (PCR)-based techniques using species-specific, genus-specific, or broad-range primers. Approximately 94.5% (n = 120) of studies used PCR assays that amplified the partial RdRp gene of length ranging from 123 to 440 bp, followed by amplicon sequencing using either Sanger or next-generation sequencing technologies. Full genome sequencing was only performed in approximately 33.9% (n = 43), with metagenomics approaches being used in 15.7% (n = 20) of the studies. The higher positivity rate of bat CoVs were detected in Asia. Globally, the most predominant bat species which tested positive for CoVs were Rhinolophus, Myotis, Miniopterus, Scotophilus, Eidolon, Chaerephon, Hipposideros, and Desmodus. Continuous bat coronavirus surveillance using molecular methods and full genome sequencing is of utmost importance in detecting and characterizing viruses at molecular level and establishing the genetic diversity of new and circulating viruses.

zoology↗

bioRxiv2021

Estimating the societal disease burden of East Coast fever among rural cattle keeping households of Namwala District, Zambia

The study aimed to estimate the disease burden of East Coast fever (ECF) among rural cattle keeping households of Namwala District of Zambia using Productivity Adjusted Life Years (PALYs). We modified Disability Adjusted Life Year (DALY) equations for humans to PALYs to estimate the societal burden of animal diseases. We used a structured questionnaire to collect data on parameters that feed into PALY equations. We coded and entered data from questionnaires directly into Statistical Package of Social Sciences (IBM SPSS Version 20), and entered the estimated values of PALY parameters into Mathematical Calculus Software called Integral Calculator (https://www.integral-calculator.com/). We then used the integral calculator to calculate PALY equations, which we used to estimate the societal disease burden of ECF in cattle. PALYs calculations were done in three categories; PALYs without discounting and age weighting, PALYs with only discounting, and PALYs with discounting and age weighting. Results revealed that the years of productivity lost by a cow, bull, and ox that suffered from ECF were estimated at 15, 10, and 15 years, respectively. In the second category, the years of productivity lost by a cow, bull, and ox were seven, six, and seven years, respectively. In the final category, the years of productivity lost by a cow, bull, and ox were five years. ECF caused a total of 517,165 PALYs in Namwala District. The quality of life reduced in years due to disability (YLD) caused by ECF per cow, bull, and ox was 0.07, 0.07, and 0.02 percent of their life expectancy, respectively. The estimated values for the years of a lifetime lost due to mortality (YLL) caused by ECF were 35, 49, and 35 percent of the life expectancy per cow, bull, and ox. These results are important for measuring outcomes of animal health problems in terms of PALYs. The findings are helpful in future projections for the future burden of any disease and can be used as a basis in policy-making and decision-making, particularly on priorities in animal health research. We recommend that a classification of animal diseases of national economic importance should consider both the societal burden and economic impact instead of the common practice of only considering the economic impact.

scientific communication and education↗